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That's great that reflowing solder joints helped resolve some of your problems. Some were never done properly at the factory, and on top of that, gig wear and thermal cycling over many decades can only add to the potential for issues in this regard.

The reed bar shields do make a noticeable improvement when added to a model 200, in my experience. Well worth it, IMO, if for nothing else than that they significantly reduce hum when you have the main hum shield off to adjust the tuning or action.

Re: volume being low. Could be something with the amp but it could also be that the trimmer pot for the pre-amp gain is adjusted too low or has some dirt/corrosion impacting signal continuity. That is the part that looks like a plastic wheel, soldered to the amp PCB to the right of the reed back input RCA jack. Mark the current position somehow and then try adjusting it to your taste. Too much gain can introduce distortion, but you might like it a little crispy sounding.

(Edit to add: if the signal crackles when you adjust this trim pot, it could benefit from some contact cleaner. you might spray some in there anyway, even if it doesn't seem to be a problem)

The main trem parts are as follows:
TR-4 - driver transistor
C27,C38,C44 - nonpolarized poly/film caps, all .12mfd/75V
R32,R33,R43 - resistors, various values - R32 is the primary one for adjusting the tremolo frequency

Check the function and connections/continuity of the trem potentiometer first. If the pot isn't working or isn't properly connected to the amp, the trem won't have any effect on the output.

The resistors and caps might be fine but they are cheap and widely available. I wouldn't bother replacing the transistor before doing the other components, unless you happen to have spares on hand already, or are placing an order with a specialty supplier that has these transistors.

Old-style carbon comp/carbon film resistors can drift in value with use and age. If they drift far enough from spec, it can detune the oscillator network causing it to become unstable and cease functioning. In some cases, replacing the resistors might be all that is required to get the trem working.

Adding that another reason for massive hum could be bad or missing ground connection of the pickup output. If you disconnect the reed bar from the amp, you can remove the pickup noise from the equation as part of troubleshooting.

But you definitely need the hum shield, and I recommend adding the reed bar shields to any 200. Those make a big improvement in noise floor, IMO

+1 To Steve's questions - where is the hum shield?

From the factory, a 200 would lack the reed bar shields that are located between the dampers and the pickups, as found on a 200A, but either model should definitely have the larger L-shaped hum shield that sits over top of the dampers. If your piano has neither shield, you are going to have a massive amount of hum like this - and no amount of money spent on a replacement amp will solve such a problem.

I've attached images of the hum shield and reed bar shield to better identify what I'm referring to.

As to the tremolo circuit, there are a few typical reasons why it might be malfunctioning on a 200-style amp:

*Caps and/or resistors in the trem circuit that have drifted in value to the point that the oscillator is longer stable. these passive components are cheap and easy to replace. You may need to try different resistor values to dial in the trem speed once you get it working. It can also make a "thumping" sound if it's not quite tuned correctly.
*Tremolo driver transistor is kaput
*Could be a bad potentiometer or else an issue of continuity in the wiring to the pot
*Some combination of the above
*Possibly none of the above

[new]

Maybe there is a generous soul still lurking here with a bin full of these cables in good condition. But if otherwise: just buy a new cable. There is one vendor on [the big music gear listing site] and one on [the big auction site] selling them for around $50 before shipping - don't pay $130 or whatever some of these internet bozos want for rotting vintage junk.

I guarantee you won't cry about the price a year from now. It's like having a sports car in the driveway but you don't wanna pay for the ignition keys, meanwhile your investment is reduced to an enormous paperweight. Not to put too fine a point on it, but if you are worried about the cost of the power cable, you're not gonna like the price of replacement reeds either.

IMO, folks should not be using a mains power cable that's ~50 years old anyway - get a new production item for the sake of safety if you are not going to mod the piano with a standard IEC320 inlet.

From what I've observed over the years, these cables used to be expensive because they were hard to find, and now they are expensive because Wurlitzer prices are through the roof. Can't win.

FWIW, this is also known as a PH163 connector. I have some old Hewlett-Packard test equipment from the '60s and those use the exact same type for the mains inlet.

I can confirm the wrench I have is 3/16" as well. If you are in an area where it's easier to find metric tools, 5mm would probably work fine. In my experience there usually isn't enough torque required to where I'd worry about stripping the wrench flats with a slightly too-big wrench.

On that note, my wrench is actually slightly oversized and also tapers out a little bit at the opening. To be honest, I can't remember if I modified it myself to be like this! It does seem to help get it more easily seated on the capstan flats, given the obstructed visibility and limited room to work.

Absolutely! I hope I didn't come across as too harsh, or judgmental of your capabilities. I just feel it's better to strongly advise caution on this subject, rather than encouraging folks to jump in head-first when the consequences are potentially lethal.

With some basic instruction and guidance from an experienced mentor, you can absolutely gain the knowledge, techniques and skills necessary to safely work with hazardous voltages.

This thread has been dormant for nearly 8 years, and the member who first posted hasn't logged in for over 3 years! I'm not a forum mod, but I believe you were correct to start a new thread with your question about wiring for IEC conversion.

Anyway, don't assume that *any* existing wiring is correct. "Assumption is the mother of all..." See my reply on the other thread, please don't reply here.

First, if you don't know what you're doing with electrical wiring, don't mess with it. Especially when it comes to mains voltages. You could injure or kill yourself or someone else, or you could start a fire, or all three.

If you have to ask if green is ground, then you have some homework to do, and you should ask for assistance from someone with experience.

But for the sake of providing some useful reference info, which readers would do well to independently confirm instead of relying on a forum post:

Black (US standard) or Brown (int'l standard) is hot or "line"
White (US) or Blue (int'l) is neutral
Green (US) or Green w/ Yellow Stripe (int'l) is earth ground

Wurlitzer EPs with what appears to be original wiring most likely adhere to US standard, but you can't be certain, since they are all old at this point and may have been altered since originally manufactured.

IEC 320 C14 receptacles (aka "power inlet") are often labeled with L, N, and ⏚, which correspond to the conductors noted above, but may not always be labeled.

Attached is a C14 pinout diagram as seen from the normally-visible side. Of course, the terminals on the other side will be mirrored from this view.

Note also that the original oval-type power inlet is lower-profile than a typical C14 inlet, and the wooden case may need to be modified to fit the substitute component, either in the original location or somewhere else.

I've installed a Borish 200B for client - they wanted it put into a 140B tho, which, aside the need to fab a custom hardware solution with zero support from the vendor, we both determined we didn't care for the sound of the stock lowpass/DC blocking filter circuit. As I've not auditioned one with a 200-series piano, I can't be sure if that's just how the amp sounds generally speaking, or if the fact that it was a 140-series model made any difference.

Anyway, I changed out the wima film cap for a different value to raise the filter cutoff frequency and I think it made a significant improvement to the sound. Fortunately it is fairly easy to tweak this component value, as it's a through-hole part and not SMD like pretty much every other part on the Borish preamp board.

In considering the options for this client, before choosing the Borish we also looked at that viva-analog post, but the info shared was a bit unclear to me and the long string of ALL-CAPS discussion in the comments was hurting my brain to try to follow.

For my part, I can't call this approach a "passive" conversion - a bias voltage is necessarily applied to the pickup, else it does not produce any electrical signal on the output whatsoever. There's no such thing as a passive Wurlitzer EP, because it is unlike a guitar or passive Rhodes that produces signal via electromagnetic induction. My preference is to refer to these types of amp alternatives as a "minimalist bias supply/preamp"

If more ventilation holes are added near the bottom, wouldn't that help with the air flow? I don't mean just randomly adding holes in the back, but towards the amp on the bottom.

There's already a hole by the amp at the bottom. Adding more holes near the bottom/inlet won't add to the overall ventilation capacity unless the exhaust/upper open area is increased proportionally, or if it was already larger to begin with. Putting a hole on the other side where the amp is not located would be less effective or even counterproductive in terms of establishing convective airflow over the amp/power supply.

For passive convective ventilation, if the inlet and exhaust are not equal in open area, then the ventilation capacity is roughly determined by the smaller of the two.

The rule of thumb I use is 1 in² of open inlet AND exhaust area each, per watt. We can use nameplate power consumption to be totally sure, but the affordances can be shrunk significantly if we are able to confidently calculate or estimate the overall efficiency.

For example if there's a 100w device  that operates at 85% efficiency, there's 15w of waste heat to vent, so you need at least 15in² of inlet and 15in² of exhaust, with the inlet low and the exhaust high and on the opposite side of the components that require cooling. The positional arrangement generally optimizes convective flow.

Ground loop hum is common with solid state Wurlitzers, in my experience. The intensity can vary depending on the particular scenario - what it's plugged into (and what else is plugged into that as well that shares a ground plane) single vs. multiple mains supply circuits for various gear involved, etc.

Doing some troubleshooting as discussed in thread here is good to sort out, for example if there are particular scenarios that are worse than others. Recently I was getting a lot of noise on a new recording setup, and it turns out the source of noise was a mixer I was using to submix the drums mics going to another mixer feeding a tape machine. I had to put a ground lift on that piece of gear to quiet things down, but it required making changes one-at-a-time to narrow in on the noise source and solution.

With Wurlitzers, I typically just deal with it in live settings, and if I need a lower noise floor for a recording, I use a ground lift plug. From a standpoint purely accounting for electrical safety, this is not recommended. However, my personal assessment is that there aren't really that many grounded/conductive bits on a Wurlitzer 200/200A that are exposed to the player, other than the sustain pedal. It's not quite the same risk, IMO, as a microphone or guitar strings that come into direct contact with skin.

Caveat: I am not an electrical engineer nor licensed electrician, but I do work with electrical safety design and assessment as part of my job. Do not follow my example without first carrying out your own assessment and decision-making process.

[A]

No updates on the panel design/tests yet but I did want to correct what I wrote at the top of this thread. It turns out I do have a 720A - I was mistaken because the nameplate has "720" printed upon it in the typical fashion, and then the letter "A" stamped into the metal. I didn't notice the "A" before crawling around down there with a flashlight at some point recently.

For reference, the serial is 40690, so that seems to put it on the earlier end of "Series 1" 720A production, according to Doc's model rundown. That would jive with a possibility that they were using up old "720" nameplates and just stamping the "A" into them, unless that's how all those were done across the entire period of production prior to the debut of the 720B.

I can look at the transformer and speaker date codes at some point to add some data. Sorry my thread is drifting slightly, topic-wise, but I figure it's an OK place to add some model data.

Adding bigger/more holes near the amp is probably not optimal with this design. The warm air rising off the amplifier then exits the enclosure through the two upper slots due to convection. This establishes an airflow current which draws fresh air in through the bottom vent by the amplifier. It's a passive ventilation scheme that behaves somewhat like a fan blowing air over the amp.

If the lower hole is enlarged without a corresponding increase in the open area of the upper vents, then it probably won't make much of a difference in the amount of cooling, and could potentially reduce the cooling factor if for example it creates turbulence that disturbs the convective flow.

Think about how a wood stove/fireplace works - you need enough chimney height so that it "draws" else if it's too short then you might end up with a room full of smoke/hot gases.

@wordsandsigns apologies if I missed this being addressed previously, but have you noticed if fussing with the volume knob has any affect on the "fuzzy" sounds? My first hunch with fuzzy or crackly sounds from any piece of older or heavily-used gear with a volume knob is that the potentiometer has some crud inside of it, or some other factor that would mess up the continuity of the signal.

With a Wurlitzer EP, "fuzzy" sounds I hear have often traceable to dirt/crud/moisture in the pickup and reed/ground interface, but it sounds like you're not getting signal from your pickup.

Another place I've noticed issues, particularly in my 720 (non-A, non-B, with tube amp), is at the RCA jack for the pickup. Fussing with that connection sometimes makes all kinds of horrible sounds come out. I've tried contact cleaner but I think the next step for me is replacing the entire wiring harness and connector hardware, which some pro techs recommend anyway as a means of reducing noise floor in this model (along with relocating the power switch away from the volume pot and down to the rear panel of the amp)

So if your RCA cable is original you might consider replacing it with a new one. But before I would bother with that, I'd double check all the solder joints in this part of the circuit to make sure none of them are iffy.

I was thinking about this some more and it makes sense there are reports 145 amps can fail in the portable models if left on for extended periods of time - there's barely any ventilation affordance in that cabinet! There's the one array of slots on the bottom face (below the speaker, on the other side of the cabinet brace/bulkhead from the amp) and then the cutouts for the power cable, fuse holder, extension speaker and phono jacks.

There's no upper vent to encourage passive convective cooling, and I doubt the painted steel lid is efficient enough at radiant cooling to do much.

In the 720, at least the hand-hold cutouts are above the amp, encouraging convection flow. I'm thinking to test the potential difference in sonics, I could just shove a piece of plywood up against the back face of the console. Anyhow, that didn't stop me from whipping up a quick model, screenshots attached.

I can lasercut this out of butcher paper or cardboard to check the fit before bothering to cut some masonite (even though that stuff is cheap, we don't generally keep a lot of it around the shop space that I have access to)

If it fits well enough, I'll be happy to post a drawing and a dxf so folks can more easily make their own if they like. This layout hews close to the original examples I've seen photos of, in that the amplifier is mostly covered up except for the rear panel connections. I thought about making the cutout taller so more air could flow over the tubes etc but then I'd also want to enlarge the upper slots to match the area of the lower opening.

I've read a couple of Doc's posts here about the 145 tube amp being susceptible to transformer failure, especially (according to them) if left powered on for long periods of time:

https://ep-forum.com/smf/index.php?topic=10145.msg56515#msg56515
https://ep-forum.com/smf/index.php?topic=9541.msg52622#msg52622

My 145/720 amplifier has a replacement output transformer but the power tx appears original. I suspect it's just as likely the output was blown due to operating the amp without a speaker load as it is to have failed due to overheating under ordinary use. The transformer mortality rate is a bit of a tangential topic but worth citing when thinking about this. From your story it strikes me as possible and likely that a number of back panels were removed (and then lost) due to a perceived need for more ventilation. It is also likely that many back panels were removed and lost for less intentional reasons.

In pursuing this idea I'd apply the same principles I use when designing equipment enclosures at my day job. Since the amp is in the bottom of the cabinet and there are already vents/hand-holds at the top, passive convection is the existing and preferred solution here (else it needs fans, etc). I use a formula that relates open area of the ventilation affordances to the amount of power that needs dissipating, in relation to ambient temps and a target operating max temperature. I am considering the surface area of the wood enclosure to be a non-factor in terms of radiant cooling.

So it may well be a good idea to increase the ventilation affordances, and I'd have to do some measurements and calculations to assess the design needs.

FWIW, adding more/enlarging the outlet vents doesn't matter unless the inlet open area is correspondingly large enough to avoid restricting the convective air flow. As an analogy, if you're inhaling air through a straw it doesn't matter if you exhale it normally, you're going to notice something feels a bit unusual...

Had some time this morning to hunt around for images and found a few in places I hadn't seen before. None of these are of a 720 (or 720A) with the tube amp, and I'm not sure whether or not Wurlitzer would have designed the panel any differently for the solid state variants.

The 726B that is pictured was shown on the Tropical Fish Vintage site and later sold on Reverb which included a lot more photos, which is where I ultimately found that image. Note the extra cutouts for the student model multi-pin plugs:

https://reverb.com/item/5692439-wurlitzer-720-electronic-piano-with-vibrato-in-walnut

I also found a 720B listing on Reverb that shows the back panel in full:

https://reverb.com/item/12335086-wurlitzer-720b-vintage-electric-piano

Also found back panel images from a couple examples of the model 700, which seems to indicate Wurlitzer may not have added any extra ventilation for the tube amp variant, but I can't say with certainty:

https://reverb.com/item/80893036-wurlitzer-700-64-key-electric-piano
https://reverb.com/item/84021807-excellent-wurlitzer-700-serviced-and-tuned-includes-unobtanium-bench-and-music-stand-extremely-rare (image is actually from a CL ad for the same item)

This is probably enough for me to go on, though if anyone has an actual 720 or 720A with tube amp and the original back panel, it would be nice to confirm whether there was any design variation such as additional ventilation etc.

Thanks for the input!

I'll add that if I'm able to get enough intel to reproduce the original design, I'll gladly produce and share out a technical drawing and CAD assets for others to utilize.

Greetings all, for a long time I've been thinking about fabricating a back panel for my 720 (non-A/B - it has a 145/720 tube amp and the nameplate says only "720")

However I have never been able to find any image of any model 720 variant with a back panel in place.

Of course it's an assumption that it was even provided with a rear panel to begin with, but there are screw holes in places that make me suspect it was the case. As well, in my ancient digital copy of a xerox of the 700 service manual, there are a couple of grainy B&W photos which show there is indeed a back panel on that one. Those can be found on pages 700-4 and 700-5, where the procedure for removing the top cover is explained.

In all the digital copies of the 140/720 service manual I have seen, there is no mention of this component nor any photos.

My interest in this is both for the sake of keeping dust out of the action and reedbar area, possible enhancement of EMI shielding, as well as the possible changes in frequency response that come from having a more fully-enclosed speaker cabinet. My 720 has a 12" speaker, FWIW. Of course, port size and geometry can have an effect, and I'm not sure whether or not Wurlitzer would have concerned themselves with this or not.

I am guessing any full-size rear panel has to have some cutouts for hand-holds underneath each end of the dividing panel between the speaker/amp area and the action/reedbar area. As well as a cutaway for access to the amplifier. These together would provide some airflow for cooling of the amplifier, and I'm wondering if there were other features such as additional ventilation or access cutouts.

I could design something from scratch using these common sense notions but I am interested in seeing what the original design actually looked like. I also assume it was probably made from masonite paneling, 3-6mm thick, in keeping with the typical conventions of the era for back panels of audio electronics cabinetry, but being able to confirm any of this would be great.

Hi, i'm the OP from that post you reference! So long ago, I didn't even have a camera or phone to document the mod. I've haven't even logged in here in forever, somehow I randomly browsed to this post looking for something else. But, that original mod is still working great and definitely is useful at every gig.

I've not done this mod to a 200a amp but inspecting the schematic, my guess is you want to focus on R12, shown as a 27k resistor in my copies of the manual. From a circuit topology standpoint, this is the equivalent component to the one I mod in the 200 amp. It's a "twin-T" oscillator, and this is the resistor that has a junction with two caps on one side and ground on the other.

As to your second question, first check that the resistor value is actually 27k - it's possible it could have been altered from the schematic to tune the circuit. Once you know the resistor value, remove it, and in its place try a 25k linear pot in series with a resistor that's a bit lower than the value of the original component. Say an 18k or 22k to start if it was a 27k.

What you want is to be able to test the range of outputs for both musicality and also stability of the oscillator. I found that extreme values will cause it to cease functioning. You might need to try different pot values if the first one doesn't provide a broad enough range on top of the series resistor.

I've also done this type of mod to 140b amps numerous times. IMO if you're DIY-inclined it's worth trying, at least on the bench before you commit to hard-wiring and adding an external pot. Happy soldering...

It's another name for threaded rod - like a machine screw with no head.

I thought about this approach a bit and I'm not sure I'd be into drilling new holes in the harp casting.

But if it would fix the sustain issue, then maybe that's the way to do it.  It would certainly avoid the heat warping issues that are possible with welding.

In any case I haven't had time lately to investigate further. The client isn't in a hurry to get this back so I have time to think about it.

That's a good question, and a good experiment to try, thanks for the idea!

I'm not sure how much clearance there is for a c-clamp in there but I'll check it out when I go to work on the action setup.

Greetings all, been a long time since I posted.

I sort of took a break away from doing Wurlitzer repair but recently started taking on a few projects again, and trying to make progress on a few old ones.

I have a model 700 in for the typical damper felt replacement, along with a cleaning, action lube, and general setup work

When I went to reinstall the reed bar after working on the dampers, I noticed the two small braces that go from the front to the back were cracked. Either the casting had internal stresses that eventually fatigued (or it was dropped, or the reed bar screws were mis-adjusted and twisting it at some point in its life)

It seems to have less sustain than another 700 I used to own, and several 120s that I've worked on, although none of those pianos ever seemed to have a remarkable amount of sustain compared to the later models. Still working on setting up the action so maybe that could change, as the let-off is still way out of adjustment.

I'm inclined not to worry about fixing it (not a primary instrument or major studio piece for the client) but curious to know if anyone's ever encountered this or attempted a repair.

My guess is it could be carefully TIG welded (I am a welder), but I have no idea what the alloy is, and am concerned the casting might be somewhat porous leading to difficult welding. Dirt/oxidation is the enemy of a good Alu weld.

Physical distortion might also be introduced during the heating and cooling cycles, and the last thing I'd want is to warp the reed bar even further.

Not sure - it's probably not critical anyhow, it's basically a tone control on an instrument-level signal.  Certainly, it doesn't need to be gigantic, but you can't go wrong with too large a rating.  A ceramic cap would work too, I used the film cap because I had some lying around already.

Note that the 35V electrolytic is what was on the VV kit that I am essentially copying so I just stuck with that.  I'm not an electrical engineer and their circuit works well so I left it as is (other than the resistor mod that I did to tame the signal level).

As I said before, there are probably a bunch of other ways to do it (I can recall seeing at least one or two mentioned here or on the yahoo Wurly group), so don't take this as the gospel.  I just know it works for me!

Also I can't stress enough that the credit for the basic circuit design is due to Vintage Vibe.  I've learned a ton from what they've shared with the community - in combination with this forum, it's been critical in developing my own understanding of how these instruments work and what they require in order to function at their best.

I got the terminal strips from an electronics store that was closing years ago.   RatShack sells a cheaply-made version but they break easily.  It might be possible to locate a source for higher quality parts but I haven't looked yet.

Also, pretty sure I just used the existing 1/4" jack in this case since it's a simple guitar-style jack and that's all that's required.  If the jack was questionable I'd put in a new one.

If you want to make an outboard filter, simply put this circuit in a project box between two 1/4" jacks.  If you're careful and handy with the soldering pencil, you don't even need the terminal strip.  Output side is the same as drawn, input side takes signal from the jack tip, ground from the ring.

Ok, so I looked at the 146 that I'm working on - turns out I used a 50k linear pot for the vibrato control.  I think I initially tried the spec'd 100k linear and the adjustment was too crude - no vibrato til about halfway/two-thirds and then very difficult to dial in the desired amount.

Pretty sure I tried a 25k also but that wasn't enough to kill the vibrato when all the way down.  100k log taper might be the way to go, though my local supplier didn't have one in stock and the 50k seems to work fine for me.

I'm attaching a schematic I threw together and some photos of my aux out filter approach.  I have to give credit to Vintage Vibe for the basic circuit design, though the one I purchased from them came with a 100k resistor on the input side which I found to allow too hot of a signal.

I experimented and found 470k to work nicely, but you might investigate on your own to see what works best for you.  The cap that goes from there to the jack tip is for DC blocking, I believe, and the components that connect from signal to ground are essentially a filter for noise and undesirable high frequencies (similar to a tone control on a guitar, but non-adjustable).

The terminal strip is bolted into a pre-existing hole in the chassis.

Yeah, I typically do that to all the 140-series pianos that I work on, they can sound absolutely phenomenal through a good amp.

You can just buy the outboard box or the internal mod kit from Vintage Vibe, though lately I've taken to using their circuit design as the basis for aux out filters of my own construction.  I found that I usually had to tune the output level of their units by swapping out a resistor and it uses only a handful of parts anyhow.  It's like $2 worth of stuff, couple of caps, couple of resistors and a terminal strip.  If you make an outboard unit in a project box you can even get away with doing point-to-point wiring between the two 1/4" jacks, it's that simple.

There are probably a bunch of different ways to do it, though I can maybe post a schematic and some photos of my approach if I have time at some point.

Not a dumb question - in this case you're using the pot as a variable resistor, so you only need the center lug (which is the wiper) and one of the outer lugs.

The choice of which outer lug to use depends on how you want the pot to behave with regard to rotational orientation  (Clockwise vs Counterclockwise for on/up) - double check with a clip lead/etc. before you solder.

Looking at the schematic, you can see that Pin 5 goes to the center lug/wiper and Pin 2 goes to the outer lug, but functionally in this case I don't think it really matters.

Hey, I had posted last year on the 140B thread you mention - turns out I am actually (very slowly) working on a 146 for a friend right now which involved adding a vibrato control.  I don't have my notes from that project in front of me right now but you're pretty much on the right track.

Basically you need pull out the student switch and associated wiring and add a control pot for the vibrato as indicated in the 140B schematic.  Because the vibrato circuit is so old (component values may have drifted etc) it may need some work to get it tuned and functioning properly, but the first step is installing a pot.  You can do this with clip leads to do a quick check.

And actually you don't even need the pot to check the functionality of the vibrato, you can just put a jumper across the contacts that the pot would connect to - vibrato should go full on if the oscillator circuit is working.

Can't recall whether I used the spec'd 100k linear pot or something else - will check on that later when I can get to my workbench.

Naptha (also sold as lighter fluid, white gas, lantern fuel) works tremendously well as an adhesive remover, and is much safer to use around plastics than acetone (and it usually works better than acetone anyway).

I have a gallon of Coleman Fuel that I use for my camping stove but I keep a small metal squeeze bottle of it (like a little oil can) near my workbench.

Tuning a reed even a semitone (100 cents) or more sharp or flat is pretty easy to do (on purpose or on accident).  The place you run into trouble is if you need to raise the pitch and there isn't much solder left on the reed to begin with.

I don't know if there's an exact formula for acceptable amounts of solder on the reed, because I've seen fine-sounding reeds in pianos that had very little or huge mountains of solder on them.  I would suspect though, that there is a range which provides optimum tone and sustain.  That's something you have to judge for yourself on a case-by-case basis.

Once I broke a reed shortly before a show.  I didn't have an exact replacement on hand so I used the next lower-pitched reed.  The difference in length was negligible, so once the solder was filed down enough it sounded perfectly acceptable to my ear.

Looking at your list, there may only be a handful that need solder or filing.  A great many of them could probably be tuned by adjusting the reed position fore/aft.

The trickiest ones are the treble reeds which have small metal plates connecting the bases of two reeds.  You have to remove both to get at one of them for solder or filing, which means you have to reposition two reeds to complete the job.  If there are any of those that need work, I'd save them for later when you are more confident in the mechanics of it.

In the case of those particular reeds,  I find that I can often avoid the hassle of removing them by using the screw-tightness method to achieve minor tuning adjustments.  I want to reinforce that the range of adjustment using that method is pretty small, and the usable range may vary from reed to reed.

Yeah, I don't know if there is anything close to a standard rate when it comes to wurlitzer tuning since it is sort of an obscure and specialized service, and on top of that it depends on the condition of the individual instrument in question.  Unless they are a big shop that does a *lot* of service, I would imagine most techs charge hourly, and maybe have set prices for certain typical services that require a known amount of labor, such as reed replacement.

In any case, since you seem to be so far from the nearest reputable tech, I encourage you to learn to tune the piano yourself.  You've already got your hands dirty with the action and the amp, may as well develop the confidence to repair anything in there, right?  It will save you a lot of headaches in the long run - when something goes out of tune you can just fix it!

I think tuning is substantially easier than action adjustments - the tuner will provide a quantitative reference with relative ease compared to setting lost motion, let off, aftertouch, etc (as well, these are parameters which may vary depending on the individual tastes of the player)

Focus on just one reed at first.  Review the service manual section on tuning a few times before you start.  It's not terribly complicated, but it requires a bit of artful concentration and patience, with a pinch of mechanical aptitude (which you seem to have).

Regarding easy ways to flatten a reed without solder, if the correction needed is relatively small, you can try loosening the reed screw and pushing the reed towards the pickup before re-tightening.  This effectively lengthens the reed by a small amount.

There is also a very fine tuning adjustment which can be made by adjusting the tightness of the reed screw.  This is possible because the reed screw washer is conical, and thus a spring which can exert a varying amount of clamping force.  There is a very limited amount of useful adjustment available - too loose and the reed will not sound properly, too tight and you run out of adjustment and risk breaking the screw.  The range of this adjustment is probably less than an eighth of a turn on the screw.

As Steve said, wax will also work in a pinch, such as right before/during a gig or when no tools are on hand.

Also I recommend removing reeds from the piano if you're going to file them.  I think you just risk getting filings in the pickup or damaging the pickup with file.  I have seen a number of wurlitzers with file scars on the pickups! Also, wipe the metal dust off the reed before you reinstall it

And make sure there is no dirt or corrosion on the mating surfaces of the screw, reed, and harp.  This will just rob you of tone and sustain by preventing good electrical continuity from the reed to ground.

If you unscrewed action parts (hammer or whip assemblies) from the main rail when you lubed the action centers, it's possible that some of the flies did not properly reseat in the catcher after reassembly.  This will jam the hammer upwards and prevent proper key motion.

You can correct that situation by gently lifting the hammer and pushing down on the jack felt (the little red square of felt at the base of the fly) with either your finger or a small tool so that the hammer can fall into the proper position.  If it is really stuck, don't force it - loosen the screws on the hammer flange and/or the whip flange to free up the stuck parts and reassemble with an extra bit of care.

Like Steve said, it's hard to tell because the amp is in the way but that's my guess.  Also, I agree that you shouldn't mess with the capstan screws (the little gold ones) until you've determined that there is a particular reason that they need adjustment.

Ah yes I had forgotten that dead-sounding reeds could be caused by insufficient connection to ground - if they do not make good contact then their signal will not be strong as that is a key part of the capacitive tone generation scheme.  I do think there is something to notion of reeds going dead that are not on the verge of breaking, though I don't have a clear idea as to the mechanism for such a condition.  I have had reeds go extremely flat before breaking, as is typical, but they didn't seem to lose much tone or sustain up until the final death blow.

But  I have swapped dead-sounding used reeds for new or NOS reeds and seen marked improvement in tone and sustain.  This after thoroughly cleaning the old reed and its interface with the harp to be sure there wasn't a poor ground connection.  (BTW one way to identify whether a replacement reed has already been in use is to check for a bright spot on the otherwise dark underside of the reed, which is a telltale sign of many hammer strikes.)

Interesting info about 140 vs 140B too Steve.  I would imagine that they were not made concurrently for very long as it seems unlikely they would have maintained tooling for both versions for an extended period of time.  More likely that they continued to assemble 140 pianos from parts on hand until stocks were depleted while ramping up 140B production, since the 140B was essentially an improved design in many aspects.

I should also add that the one example of a 146 I have personally encountered is based on a 140B and not a 140.  It has the exact same amp, even with the vibrato components present on the board (but lacking wiring or a pot to engage it), and a modified control section on the bass cheekblock for toggling the speaker on/off and selecting self/ensemble for headphone output.  Why it was not designated the 146B is beyond me.

Hi and welcome!

I am pretty familiar with 140Bs, not so much with the earlier 140, but I can attempt to address your questions.

"Dead" sounding reeds could be a number of things - sometimes reeds do just seem to turn into duds, and replacing them with a new or known good reed with no other adjustments will resolve the problem.  Other causes might be a reed screw which is insufficiently tightened (sometimes I find reeds which are loose either from vibration or perhaps hack attempts to tune the reed flat without resorting to adding solder), cracked reed screw washers, or sub-optimal strike point for that particular reed.

Non-functional vibrato could be a faulty connection somewhere, a bad pot, or more likely that the caps and resistors in the vibrato circuit have drifted in value far enough to prevent oscillation from occurring (could also be a fault with the transistor which drives the oscillator circuit).  I have found this last case to be the issue with many solid-state wurlitzers I have worked on (140 and 200 series) - replacing the caps and resistors with known good components of the proper spec usually results in marked vibrato improvement.  But it is worth checking the physical wiring and solder points beforehand, just in case it is something as simple as a bad connection.

Regarding the bulb, I am not sure about replacements.  I believe Ken Rich sells a neon bulb intended for 200-series pianos which may perhaps be workable.  I typically install a domed LED unit in 140B pianos that I restore since it removes a potential source AC hum from the control area and should last a very long time.  This requires a bit of knowledge about how to get a proper DC supply voltage for whatever LED you are using, but it is not terribly complicated stuff.

As far as I know, 140-series pianos came only in the butt-ugly schoolhouse tan/beige/whatever, in varying degrees of flecked-ness.  I have seen quite a few painted black [aftermarket] and they look pretty sharp.  It all depends on your tastes and how well the finish has worn.  I think some people have reported success using flecky rock-texture spraypaint to replicate the original finish.  I have a 140B that I am thinking of stripping and doing an oil finish, since I think they used a pretty decent veneer on the case wood.   In any case if the veneer turns out to be ugly it will get something other than butt-tastic beige.

I believe the 140 was made in 1962-65ish, not sure on exact dates.   Anyone have some concrete info out there?  The readily-available info out on the net seems inconsistent.  Pretty sure they stopped making the 120 around 1962 and I haven't seen a 140b which is older than 1965, but I may be misremembering this stuff and/or making things up.

here's a project 112 amp on the well-known auction website in case you have any interest in monkeying around with trying a different amp:

http://www.ebay.com/itm/Vintage-WURLITZER-Electronic-Piano-Tube-Amp-Amplifier-For-Restore-Model-112-/370688048116

(not my auction)

I you haven't tried a 3-prong cord that may help (really it should be done anyway for safety reasons).

If you want to try seeing what effect it would have without modifying your amp with a new socket, take a 3 prong cord, and at the end opposite the plug cap the hot and neutral leads with wirenuts, and install a ring terminal on the green (ground wire).  You can attach this ground wire to the amp chassis (at one of the mounting screws would be the easiest way to do it).

Then plug the 3-prong cord in to a properly grounded outlet (ideally the same outlet as the other, original power cord).  Because you've got the mains covered up and isolated, it should be safe to do this.  Just make sure the amp is off and everything is unplugged when installing the temporary ground connection on the amp, if there is stray voltage on the chassis it could arc when offered a path to ground.

If using a 3-prong seems to help with the hum, I'd recommend replacing the 2-prong cord with a 3-prong.  It would be wise to do so anyway for safety since there are high voltages in the amp, but in the past I have noticed at least of couple old tube models that produced less hum with the ground lifted (only through the internal speaker - the headphone/aux out was quieter with the ground in place).  They were operating in a more dangerous state but I knew to be very careful and only ever used a cheater plug to temporarily lift the ground, rather than permanently altering the cord or amp.

Electrolytic caps do tend to fail with age, yes.  Ceramic, not so much, although they are cheap so cost is not a factor in replacing them, just labor which may or may not make a difference.

One thing though, film type caps can go bad, even if they seem fine with a cap meter.  I think this is one of the reasons why vibrato circuits get weak or stop working (the others being resistor drift and failure or poor performance on behalf of whatever is driving it, be it a tube or transistor).

Film caps can also go microphonic as they age.  I recently overhauled a Pianet N preamp, the film caps would make noise if you tapped on them with a pencil.  New ones fixed that.

Ah, sometimes the volume pot can cause trouble - have you used a contact cleaner like De-Ox-Id or the like on the pots and jacks?  Is the volume knob very crackly when you adjust it?

For example, my roommate has a Fender 75 amp that recently started misbehaving.  The reverb stopped working and the amp generally sounded dull and noisy.  We thought it might be a bad tube or reverb tank, or something else deeper in the circuit even.

Before we decided to really start digging into it, I cleaned all the pots and the reverb and footswitch connections - it immediately sounded 100% better, with minimal effort.  Remember, the pots are part of the signal path so if the contacts are corroded or dirty then you're going to be inviting all sorts of problems.

I've also read here and there that volume pots on wurlies can be a source of hum, though there's never really a thorough explanation of why in any of the accounts I've seen - just that sometimes folks have replaced the pot and hum magically goes away.  Could be that the resistive element is worn out and leaking stray signal to the wiper??  Who knows...

One other question are you using a 2-prong or properly grounded 3-prong plug?  If 2-prong, does flipping the polarity help?  It's inconsistent, but sometimes I get more noise with a wurly with the ground in place and sometimes I get more noise with the ground lifted.  I think it also depends on the quality of the power coming out of the wall in your location.

Hmm, is the transformer noise like electric arcing, accompanied by any smell?  That could be bad - but you'd know pretty fast if it really crapped out because the fuse would probably blow.

If it is just a mechanical noise, check the transformer mounting.  The transformer on my 200 rattled like a small buzzer before I played around with the mounting, now it runs quietly (can't remember if I tightened it up or just nudged it around to keep it from acoustically coupling with the amp rail).  Every once in a while if I bump the transformer while doing other work on the piano, I can hear the same sound come back momentarily.  So it's worth checking for mechanical noise.

As far as measuring cap specs, sometimes a cap meter will tell you a cap is fine, but since the meter is testing capacitance with a very small voltage, it may not be telling you the truth about the cap's functionality (or lack thereof) at normal operating voltages.  Just sayin'.  But the fact that you have successfully run audio signal through the reed bar input is odd.

Have you measured DC voltages around the amp to compare them to the schematic?

Also, with the reed bar disconnected from the amp, what's the resistance between the tip and the sleeve of the pickup's RCA connector?  It should be completely open, as I'm pretty sure the pickup is supposed to be fully insulated from the harp.

This is long overdue, but I haven't been able to get around to replacing the reed screws on my 720 until recently.

I used the McMaster-Carr parts I mentioned in a previous post.  They have only been in the piano a short while, so this shouldn't be considered a long-term report, merely my initial observations regarding their suitability as generic replacements.

The screws are fine - the thread fit is perhaps a little tighter but not so extreme as to cause me worry about galling, seizing, other thread damage.

The spring washers are a little thinner than the original, but have more spring to them, so I noticed I was able to coax a wider range of fine-tuning from adjusting the tightness of the screw.  We'll see how the tuning holds up over time.

The main drawbacks of these washers is that they are not captive to the screw, so they won't necessarily stay on the screw when you have them off the harp.  Also, the hole in the washer is a little bigger than an original, so it floats on the screw a little more, which conceivably could make tuning a little trickier, depending on the nuances of your tuning process.

Taking this into account, and noting that Vintage Vibe is now selling reed screws for a dollar each instead of two dollars each, I'd recommend going with the originals or repros that VV is selling, even if you need to do a whole bunch.  The only reason I went this way to begin with was that I had to redo an entire harp's worth of reed screws and the generics were a third of the cost of Vintage Vibe's parts at that time.

Tonally, I notice no real difference between these and originals in good condition.  Unless there's tuning difficulties down the road, I will probably leave them as is due to the expense and time required to replace all the reed screws again and do a full tuning from scratch, but in the future I won't go this route assuming VV's (or other future suppliers') parts remain reasonably priced.

If I'm accurately interpreting what you've written, you have the amp and reed bar out of the piano on a bench for testing, yes?

If the reed bar is just sitting out on the bench with no shielding whatsoever, there's going to be a significant amount of hum when you connect the pickup to the amp, although you should also be able to hear a signal from the reeds mixed in with that.  Is that the case, or is there no signal from the reeds when you strike or pluck them (just hum)?

If there's no signal, check C3 - it looks to be the coupling cap between the pickup and everything downstream of there.  I would imagine a misbehaving cap or connection there would give you trouble. 

Assuming you have no shorts between the pickup and the reed bar/ground, something tells me the issue lies not with the reed bar but in the signal path between it and the amp, since you say you get a decent signal using the record player input, and especially since two different reed bars produce similar or the same results.

Yes, it is the lower of the two screws which are visible from the front of the piano, hanging down from the whip.  They look like little dome-headed carriage bolts.   Lowering this screw decreases lost motion, raising it increases lost motion.  If the fly is getting stuck in the catcher then you want to increase lost motion.

You can visually inspect for the at-rest gap between the fly and the hammer butt.  Also, gently pushing down on the key will let you feel how much lost motion there is before the hammer starts to rise.

Ideally you want to use a capstan wrench that is the appropriate size.  If you only have to do a couple adjustments, you could try turning them by hand after removing a few keys to give yourself some room.  Sometimes though (especially if they haven't been adjusted for a long time) they may be very difficult to budge with your fingers.

Honestly the proper tool is a capstan wrench but if extra care is taken you might be able to get away with using something else.  I generally discourage this but sometimes ya gotta do what ya gotta do, right?  Just make sure not to damage anything if you're using an improvised tool.

Really, the capstan wrench is not a very expensive tool and it will allow you to adjust the let-off screw as well.  It's a worthwhile investment if you have any interest at all in doing your own regulation.

Oh and another reason a hammer might get stuck is if there is not enough lost motion in the action (very small gap between the tip of the fly and the hammer butt). If that is the case, the fly tip can get stuck in the catcher and fail to return to the at-rest position after a strike.

Visual inspection of the action components will allow you to discern whether the issue is the previously-mentioned fly dislocation (forgive my invention of terminology), insufficient lost motion causing the fly to stick in the catcher, or some other problem (loose/misaligned parts, missing felt in the hammer butt, etc.)

Lost motion is adjusted by raising or lowering the lower capstan screw (on the whip in 200 models, on the key in 140 models).  Factory spec for the 200/200A calls for a 1/32 gap, but I like to set it closer if possible (just at the point of lost motion), as I feel it adds more sensitivity to the hammer throw.  Different models and different instruments will have different potential adjustment limits as they are all unique beasts at this point, IMO (especially the older ones).

If you removed the hammers/hammer flanges from the action rail to shrink and lube their centers, double-check the screws are tight enough.  There is a notch in all the action flanges to help keep them properly aligned to their mating part, so it'd be kind of unusual for a hammer to strike in a different spot unless something was amiss here.

If the hammer flanges are tight to the rail and you can find no other issues, you can change the strike point of an individual hammer by using a soldering iron to soften the glue that holds the hammer tip into the hammer butt.  When the glue is softened you can bend the tip forwards or backwards to adjust the strike point and thus the voicing of that particular note.

Also, regarding hammers not falling back down - when reassembling action parts after having removed them from the piano for whatever reason, sometimes the fly can fail to resituate itself in the notch in the hammer butt.  The jack spring could be pushing the fly backwards, jamming it up behind the hammer.  If that were the case you'd have to lift the hammer up and gently pull the fly forwards until it could reseat itself properly.  It might be helpful to remove the key while doing so.

BTW there's tons of great info in the 200 series service manual, which you should be able to download from a number of places for free, including Vintage Vibe's website.  They also have a lot of videos on Youtube covering a wide variety of repair procedures.

Yep, the inside of the case is painted with conductive paint (for shielding).  So that is a ground connection for the sustain mechanism and pedal.  (If ever happen to find that you're getting extra hum when you connect the sustain pedal, you might wanna check the continuity there, or wire up a more secure connection.)

That's good info - I have experimented with modifying tremolo circuits in other amps, like Wurlitzers, guitar tube amps, etc.  First I plan to replace the trem caps with stock values, just to see how it performs, then I can set into messing about with it if needed.

What I'd really like to improve is the intensity of the trem.  When the oscillator first fires up the bulb pulses on and off quite intensely, a very distinct tremolo effect, but then it settles down into something more subtle.  I'd like to have that really choppy sound on hand since it can be quite musical when called for, but maybe it will return when I replace the caps and check the resistors for drift.  I notice a definite improvement in Wurlitzers that I perform this maintenance on, and it is essentially the same kind of circuit.

Also good to know the keyshaft grounding helps with any type of sticky pad - I suspected since they are a whole array of ungrounded aluminum rods that they would increase hum somehow, being aligned over the pickups.  My pianet is already pretty noise-free, though I should be able to get the thing dead quiet with a cap job and the extra grounding.

Somehow I missed both these replies - must not have set any notifications for them.

Turns out the Jaymar went away with a roommate who moved out so this project is on the shelf until I get ahold of another suitable toy piano.  I'll keep your offer in mind though, Rob.  In the end I think I'd need 25 pickups since it is typically a 2-octave piano.

So, Steveo, what I'm calling the soundboard is actually just the piece of masonite/pressboard that is on the back of the Jaymar.  The metal rods (like big rhodes tines) which are the tone-producing element are mounted directly to this board so I consider it the soundboard, since they are acoustically coupled.

Finally got some time to install my new Ken Rich sticky pads for my Pianet N.  The old ones in my Pianet were totally trashed and disintegrated so I have nothing to compare them to, but they work great!  I did get a service message from KRS saying some of the pads may have excess silicone grease on them, which could accumulate on the reeds and flatten their pitch.  All that need be done in that case is wiping off the excess grease from the reeds and pads.

I can't compare the old tuning of this pianet with the way it is now, but some reeds seem to have gone slightly flat during initial use, as expected.

One thing that I think is interesting is that this piano now sounds different from many of the Pianet N examples that can be found on Youtube.  I attribute that to the difference in pad material - the KR pads vs. the Clavinet.com pads which I see on almost all refurbished Pianets out there (except for the ones with the DIY rebuilt pads).

There's a rubbery-squeaky-skronky kind of click to the attack and damping that you hear a lot and I think it has to do with the properties of the Clavinet.com all-silicone rubber pads (triboelectric charging) .  Not an entirely unpleasant variation on the pianet sound - actually it can be a cool timbral quality - but I understand it can be problematic, sometimes requiring a lot of fussing over the pad placement and the keyshaft alignment.

The N that I have now is somewhere between a Wurlitzer 140B and a 200A sound, maybe a bit brighter and more present/focused, with a slightly different attack quality due to the nature of the pads vs. hammers.

It sounds pretty good for now but I am going to replace all the electrolytics and the vibrato caps since they are past due.  It's also relatively quiet considering it's still got the 2-prong cord and original caps, but I think I will also do the keyshaft grounding procedure that Clavinet.com has demonstrated on Youtube.

I would also like to mention that since I am missing the footpedal with my Pianet, I had to put a jumper on pins 1 and 3 on the footpedal jack in order to get any sound out of it.  I think I read about this issue elsewhere but I wanted to state this here for the sake of others who get into these pianos.

The schematic reveals that the footpedal is basically a 250k volume pot where pin 1 is the wiper, pin 2 is ground, and pin 3 is the return path to the amp.  The 3-pin DIN jack on my piano is not a switching jack, so without the pedal there is no sound.  As a result, this makes it a very convenient place to wire in an external volume control.

Once I get further along with the electronics, I may put together an external control box with volume and tremolo rate and intensity controls (relocated from the internal trimmer pots).

Cool, good find, would you mind posting the manufacturer part number for those pins?

I live near a big electronic distributor and all the molex-type pins they have are of a different type.  I had to harvest some pins out of a beat-up 206 that I picked up for $10 (it was missing the harps, reeds and all the electronics.  Still good for action parts and random bits though)