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Messages - sean

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You can leave it in the case to do the grommets, dampers, tips, and felts.  I prefer to be able to check my progress as I work, so it is nice to keep it mostly assembled.  Do ten grommets, play a little.  Do ten more, play a little. The hammer tips or damper felts have to be done as a whole batch so the glue can dry, so you don't get to play as you work.  But the grommet job involves re-setting the escapement and voicing, so it is nice to have the piano in playing order.

You will probably take the cheek blocks, action, and harp out of the case to do the tolex job.  If you are going to repair the case, you would take all that out, and remove the harp supports. 

You get to decide what order you want to do the work.   You could get it playable now, then wait until summertime to build a new case and do the new tolex. 

It is probably a good idea to do a very thorough inspection and assessment of the bottom of the case.  You should be able to get a good look at things by simply removing the keys and the damper release bar.  Since the case is broken, and the tolex is ratty, I would suspect that there is water damage.  If there is no water damage, then your Rhodes may have been dropped.  If the bottom of the case isn't water damaged, or cracked, or warped, then I think you should do your best to keep it.  Bondo and epoxy can do amazing repairs.  If it can't be re-used, save it as a template to locate and drill the mounting holes for the action rail, keybed, and harp supports in your new case.

I assume that you already know about the service manual on the Super Site at

Post some photos of the piano, and especially of the added electronics.


Buying / Re: WTB: 1972 Buz Watson Rhodes Stage piano
« on: December 10, 2018, 04:06:50 PM »

Hmmm... never heard of him before (but now I are an ekspurt, cuz I googled it).

also see or


The Wurlitzer Electric Piano / Re: My $20 Wurlitzer bench
« on: December 09, 2018, 09:49:52 PM »

I like it because it looks very similar to the primitive "matching" bench that came with my 200.

...and the legs do indeed remind me of kindergarten.



Since we are beating on this dead old thread...

They make "virtual ground" or "ground reference" ICs that are specialized to this task, like TI TLE2426CP.  I wouldn't bother in the case of the Rhodie preamp, because you don't need a low-impedance super-stable ground reference simply to feed an input pin on an op-amp.  The simple resistor divider does just great.

Also, I have built the Rhodie preamp circuit, and it sounds just fine, but when you remove the LM358 op-amp and put in a more modern op-amp, like SE5532 (or NE5532 or TL072), it sounds much better - like immediately noticably better.  I don't think anybody would choose the LM358 nowadays.

See Rhodie schematic and commentary at


Parts, Service, Maintenance & Repairs / Re: Yamaha CP-70 Signal Issue
« on: December 02, 2018, 05:50:13 PM »

Yeah, you have to murder those jacks to get them removed from the board.

Hmmm... did you try using alligator clips to jumper the tip connection on one jack to the tip connection on the other jack?

I see the Pout (Patch out) silk screened on the board.  Is there another terminal marked Patch In or Pin?

I believe it is just from that white wire to that red wire, but you should look underneath the board to confirm.

Have you found a circuit schematic that seems to match your CP-70?


Parts, Service, Maintenance & Repairs / Re: Yamaha CP-70 Signal Issue
« on: November 30, 2018, 09:46:31 PM »

I do my diagrams in LibreOffice Draw.

I had previously created the 1/4" jack diagram for a previous project, so I thought it wouldn't take long to create the diagram above. 

The fully-enclosed plastic jacks are not my cup of tea, but they are easier to include on a PC-board design.   Switchcraft makes this type too.   Are there any manufacturer's markings on your jacks?

The fully-enclosed plastic jacks are impossible to inspect and repair, and it is hard to unsolder and remove them from the board without mutilating them.

Have you tried plugging in a guitar cable into both of the jacks to simply jumper them?  That would be easier than getting an alligator clip lead to go from tip to tip.



If you drop your Rhodes in the ocean, the PLA pickups will only last two years.  The ABS will last for centuries.

I would think that both would be fine for just being a bobbin to hold the pickup windings, the tip, and the magnet slug.

You want to find a compatible glue to secure the slug to the tip.  Old Rhodes pickups seemed to have a lot more sloppy adhesive on the pickups than later models.  I don't even think the glue is required, because the magnetic slug holds on to the tip pretty tightly.  I bet the glued-in slug was required for factory production and parts shipment.

The bobbin material has to be flexible enough to survive the force-fit mounting of the tip.

I would think the only difficult situation that the pickup bobbin material has to endure is the soldering of the pickup terminals.  The pickup terminals get up to 850°F or 500°C when heated by a soldering iron, and the terminal can melt the bobbin and get loose or fall out.  If you work quickly, the bottom of the terminal doesn't get hot enough to melt the bobbin; but if you aren't careful and efficient, it is pretty easy to ruin a pickup.  So maybe you should choose the bobbin material based on stability and strength when heated.


The Fender Rhodes Electric Piano / Re: noisy tine problem
« on: November 30, 2018, 06:10:08 PM »

It doesn't look like the tone bar might be kissing the neighboring tonebars, but... maybe that is the problem.

Check also that the tonebar mounting screws are not loose enough that one of the washers is buzzing against the screw.
Check also that there is enough force pushing down on the mounting springs that they are not able to rattle.

Less likely ideas:
If the grommets were really rotten, the mounting screw can actually contact the tone bar.

I don't think the tine is swinging up and hitting the end of the pickup, but it does happen.  Back the pickup off the tine, and see if the buzz goes away.  This ususally makes a much more offensive noise.

Make sure that the screw holding the tine block is tight.  Make sure the tine is securely mounted in the tine block.


Parts, Service, Maintenance & Repairs / Re: Yamaha CP-70 Signal Issue
« on: November 29, 2018, 07:16:11 PM »

The problem is quite likely the 1/4" jack connectors that make up the effects loop.  All it takes is a little corrosion, and the signal doesn't get from the "shunt" connection on one jack to the other.  Sometimes you can clean the little round connection button on the prong, and sometimes you need to get them to more forcefully touch each other.

Once you have used your alligator clips to prove that this is the problem, the best plan is to simply replace the jacks.

Markertek sells Switchcraft 12A for $1.85 each.

If you want the longer threads (for thicker mounting panels), get the L12A.

I have no idea why Markertek doesn't stock the L12A, but Mouser has them for $2.70 each.


Buy it!  I think 1973 was a very good year.

These are the major differences from later years:
It will have half-wood hammers with square hammer tips.
It will have rounded-top Pratt-Reed fully-skirted white keys.
The black keys will have more angular front edges, rather than more nicely rounded edges.
It will have the split damper felts that look like tooth roots.
The action will quite likely be heavy or sluggish, so the miracle mod pedestal bump will help.
The key pedestals have their front edge beveled, but this portion does not contact the hammer cam.
The black rounded lid will be thicker than later years, and feel more like vinyl than styrene.
It still has the old-style small hinges on the back, doesn't it?
The sustain pedal is the nice old non-painted style with the original shape.
The sustain rod might have Rogers USA on the wing nut.
The control plate on the name rail is mounted about two centimeters to the left, so the output jack is about one key lower (it sits over the A instead of Bb)
The piano logos still have Fender branding.
The sides of the case and the lid are not sawed straight, they have the birds-mouth notch so the sides of the piano dip below the cheek blocks before they get to the front of the piano.

I would trade my Mark V to have my 1973 back in a heartbeat.


Parts, Service, Maintenance & Repairs / Re: Range of pickups not working
« on: November 20, 2018, 12:45:22 AM »

I think the tonebar that is just to the right of the missing three tines is touching the rear solder terminal on the pickup below it.


Parts, Service, Maintenance & Repairs / Re: Loose Keys - wobbly Keys
« on: November 19, 2018, 05:59:52 PM »

Key bounce is a shortcoming of the Rhodes piano simplified action.  Some pianos have it worse than others.  My 1983 plastic-key Rhodes bounces as bad as shown in your video.

Backchecks are the most complete solution.  I haven't ever seen a Rhodes with backchecks installed.

I have always wanted to experiment with some sort of impact-deadening material under the back of the keys.  Like some sort of solid gel or asphalt under the felt strip (see part 37 in  Maybe a thicker or looser strip of felt might help.  Maybe just a routed slot of dead air under the felt could work.  But this is a lot of work, and I don't want to do any destructive testing on my Rhodes pianos, even the plastic-key unit.

Keyweights at the back of the keys might lessen the bounce, but I have no idea how bad they would affect the feel of the action, and it would be a science experiment to figure out if they would work in this case.

Of course, neither of these two solutions would completely stop the hammers from bouncing like they do.

Yeah, so, your best options are learn to live with it, or install backchecks.


Parts, Service, Maintenance & Repairs / Re: Range of pickups not working
« on: November 19, 2018, 02:03:25 PM »

I assume that when you say 0-1 ohms, you mean between zero and one, right?
Not O-L.

Some meters show "O-L" to mean overload, open circuit, or infinite resistance.


Parts, Service, Maintenance & Repairs / Re: Range of pickups not working
« on: November 19, 2018, 01:59:23 PM »

Take a look at Jenzz Lupke's description of the 88-key harp wiring:

See also the diagram he linked in the post just above that at

You are measuring the resistance in a funny place.  If you are measuring the resistance at the wiring gaps between the front terminals on neighboring pickups, you will get something close to 180Ω if all four of the neighboring pickups are functional.

Normally, I would expect you to put your meter between the front and back terminals on the same pickup.

In a group-of-two, you would get about 90Ω if both pickups are working, 180Ω if one pickup is dead.
In a group-of-three, you should get about 60Ω if all three pickups are working, 90Ω if two  pickups are working, 180Ω if only one pickup is working.

I am intrigued to figure out what portion of the pickup wiring you say reads only zero or 1Ω.  Did you mean simply between terminals that are connected together with the bus wire (which would be obviously just right), or did you mean that you get the whole middle section is shorted out? 

The only time I have seen large sections shorted out is when I accidentally have a tonebar touching a pickup terminal, but your photo shows the tone bars removed.

Can we get a more detailed description of what is going on, and maybe a photo of the top side of the pickups?



Uhm... Go to grocery store, buy the widest roll of aluminum foil they have, take it home, roll out some foil wider than the Hammond, lift up the Rhodes, lay down the foil, get an alligator clip, and connect the foil to any audio ground, done.  What's not to love about pnoboy's solution?

If it doesn't work, then you can put the aluminum foil in the kitchen drawer, and forget about it.

If it works, then you are done.  If you want to make it cosmetically more elegant, then you can glue the foil to a layer of posterboard.
After you prove that the shielding works, if you want to make it more durable and complicated, you could use roof flashing, but you will risk cutting your fingers.

We assume that you have tried the Rhodes in another place somewhat far away from the Hammond, so you have proven that there is no interference when the Rhodes is a few feet away from the Hammond.  Right?  (Because if the noise is still there, then it would not be EMI, it would be noise coming through the AC mains from the Hammond to the Rhodes or to the amp.)


P.S. - I don't think it is worth the hassle to try to put the shielding inside the Hammond or inside the Rhodes.

The Wurlitzer Electric Piano / Re: Wurlitzer 206a - To chop or not to chop?
« on: November 05, 2018, 05:03:33 PM »

I am on team Don't Chop It.  The result is still a heavy beast.  It is a lot of work, so also I am on Team Lazy.  I also think the time, money, and effort spent on the chopping modification would be better spent on... finding and buying a 200A (or another keyboard, Swedish or otherwise).

I think my 206 does sound bassy, but I have it in the basement, and the 40-year-old speakers are pointed at my knees.  You can use the 1/4" output to go to the house, or to a mixer to split it into monitor and house and headphones or whatever. 

However, if after listening to all us naysayers, you still are inspired to chop it, then you know in your heart that you should.



Two things to look for:

1. Hammers that move side to side should make you suspect that the hammer comb is cracked.  I mean the hammer  mounting flange. 

2.  Each hammer has little bumps or pins that fit into the flange, sometimes the pins are broken off.



Well, you didn't say which of the three Janus preamp circuits you are interested in building.  But in any case, the hardest part to source is the LDR.  Get your hands on that, and the rest is pretty simple.  Vintage Vibe has them.  But this one obsolete and expensive part could ruin the economics and fun of this project.

Also, I really wonder why in the world you would want to build a Janus preamp.  The Janus preamp never gets much love online, everyone says that the Peterson tremolo is tons better.  If you want to build one because you want a really good preamp for your Rhodes, you would be much better served by spending your money on a modern preamp and a tremolo/leslie simulator. 

If you want to build the Janus preamp as a lesson in electronics construction, then okay, I guess.  It is a pretty good challenge, because it is seventy-some components, with five pots to mount on a front panel while mounted to the circuit board.  I don't think I would enjoy building something this big on veroboard, but you could design the board using something like DipTrace, and then send off the Gerber files to have it fabricated.  That is a lot of work, and it will be nearly impossible to get it right the first time.

Then you also get to build the power supply, that's the only part that I can help you with...

After all that work, you will have a mediocre single-purpose preamp. 




Now I get it.



Wow.  If that really is the tone control circuit in the Piano Bass, I bet the tone control is unimpressive.

Circuit simulation leads me to believe that the circuit rolls off everything above 2700Hz at roughly 6dB per octave, and the tone control knob just brings that rolloff down toward 880Hz.  So it removes high frequencies that are not really dominant in the source signal.  It wouldn't really affect the ballsy low bass tones of the long tines in the Piano Bass.  It might knock out some pingy overtones maybe?  Doesn't sound very useful to me. 

Was this circuit really used in all years of the Piano Bass?



Try again.  That one is not stocked.

You should have no trouble finding a film capacitor.  You will pay more for shipping than the cap.  Arrow is desperate enough to give free shipping, I think it requires a $20 minimum, but maybe not.  Arrow's website sucks, but you can eventually find what you need there.  0.2uF is not as common today as 0.22uF, so Arrow has few to choose from, but this would work: 
Mouser and DigiKey have lots to choose from, including:

Those are all similar PolyPropylene caps.  If you want a ceramic cap, then the choice of two .1uF caps becomes more obvious - 0.2uF is not a common value in ceramic capacitors.  Values of 0.1uF or 0.22uF are much more common. 

BUT WAIT!!!!    What makes you think that the capacitors in your Piano Bass have failed?  These caps should be pretty reliable in this situation.

Have you checked the pot with a meter to verify that it is functioning correctly?  Have you sketched out the circuit to make sure that it makes sense and is all still connected right?

Anybody got a schematic of what the Piano Bass name rail volume and tone controls should be?



You need almost ten feet of 1/4" black tape.

3M 1350F polyester electrical tape would work, and the 1/4" width shows up on Amazon.
Looks like 3M 471 tape comes in 1/4" widths too.

Graphic artists use 1/4" tape, so you can get it at art stores.  Staples sells it.

If you really want the textured tape then you might have to search harder.  I guess you could try to slit the 1/4" strip from a larger piece of vinyl or tolex, but that seems like a difficult job.  If you have a local upholstery store, they might have a suitable textured material, and may be able to cut it more accurately than you can at home. 


Preamps, Modifications & Upgrades / Broke the wire off the pot...
« on: July 30, 2018, 03:02:02 PM »

Your namerail wiring should look like the schematic, drawing, and photo in this post:

We are not afraid of Kindergarden questions - we are happy to help. 
Many of the simple questions are covered in the service manual:
Some good stuff in the technotes:
Lots of good stuff on Vintage Vibe's website, and their youtube channel.
Lots of good stuff on RetroLinear's website, and their youtube channel.


The Fender Rhodes Electric Piano / Re: Miracle Mod Install Problem?
« on: July 20, 2018, 04:41:00 PM »

The factory team installing the felts and paper punchings was from ∀nsʇɹɐlᴉɐ.

Even with the best of amps and speakers the Pianet T is not huge champion of dynamic range.  You can't really expect the sticky pads to do as well as a hammer.  I think even the pad against anvil arrangement in a clavinet provides more dynamic range than the Pianet sticky pads.  Hitting the Pianet keys as hard as possible is not proportionately different sounding from hitting the keys medium hard.  I have a hard time making a Pianet sound as expressive as a Rhodes, Wurly, or that keyboard-thing with long wound strings stretched over an iron plate.

But the sticky pad is just the nature and beauty of the Pianet.  I think the bass notes on the Pianet T suffer more than the other notes.  I think a little more aggressive attack might give them more clarity, and it would be great if they had more punch.  But sticky pads....

Hmmm... maybe we need sticky pads that could be told "Okay, now, let go of this note really hard!"

If you are enjoying your Pianet T, just wait until you have a Wurly or Rhodes to tinker with!  On a Rhodes, if you don't like the sound of the bass notes, you can adjust the pickup position, strike line, escapement, hammer tip hardness, and tine position against the pickup tip (timbre).  The Rhodes is very responsive to how hard you hit the keys, so you get pretty effortless control over the dynamics.  If you want to further isolate the bass notes (so you can apply specific equalization, envelope follower, or other effect), then you can split the harp.    (See

The Wurly has a "real" piano action, so it is wonderfully expressive as well.

Maybe the better control of the dynamics might not clear up all your expectations for tonal perfection and clarity - it might still sound muddy or nasal.  Then we must blame the physics of the Pianet tine... just a floppy piece of steel.  Or blame the inductive nature of the Pianet pickups. 

I think you will eventually get the Pianet T set up as best as possible, and you will get used to its characteristic sound. 


P.S. - Most pianists have two hands, so maybe you could play the Pianet with your right hand, and another instrument with your left.  That would be another way to get the sweet sound and great clarity of the pianet high notes, and not the wonkiness of the pianet low notes. 

The Fender Rhodes Electric Piano / Re: Key Pin replacement problems
« on: July 16, 2018, 03:24:06 PM »

So you could purchase a long section of pins, and then simply cut it to fit.  Carefully measure to cut it, and then more carefully locate the screw holes when you screw it down to the wooden case of the piano.

Right, Ben?


Parts, Service, Maintenance & Repairs / Re: Pianet T Rust Removal
« on: July 16, 2018, 03:04:14 PM »

I wonder if oiling the tines would interfere with the stickyness of the pianet pads.  If you do it, try it first on one and only one tine.  If the sticky pad still plucks the tine, then your next worry is the chemical interaction with the pad and the lubricant (or any solvent or propellent in the lubricant soup).  I don't think I would oil the tines. 

Scrubbing with CLR would probably work to remove some rust.  It won't leave the surface shiny and bright.
The MSDS says that CLR is lactic acid and a surfactant (lauramine oxide).

Tim recommends Evaporust.
Evaporust is advertized as a chelating agent - it grabs the iron molecules from multiple sides.  I wonder if it is mostly EDTA.  The MSDS for Evaporust doesn't tell you what it is, except that the pH is 6.1 - so it is a mild acid.  The EPA and FDA say that EDTA is safe to play with and eat, so the Evaporust folks wouldn't have to state any danger on the MSDS.  But Evaporust could be some other chelating agent maybe.  Evaporust is available online.

There are other acids that work against rust:
Oxalic acid (Bar Keepers Friend)
Carbonic acid (baking soda)
Acetic acid (vinegar)
Phosphoric acid (Krud Kutter, Coca Cola)

The Oxalic acid products work well, but they will dull any shiny metal nearby.



The 820Ω resistor goes from the +9V output to ground.  In parallel with the 10uF capacitor (C2).

This resistor simply creates an 11mA drain on the regulator output, so that the regulator never starts sputtering.  I think that when the output current gets close to zero, the comparator in the over-voltage protection circuitry freaks out.  You won't hurt the regulator if the output current goes to zero, but the output voltage will get an ugly dose of ripple and buzz. 

The spec sheet for the regulator clearly and completely explains this with Note 1 on page 1:  "Note1: No load operation will not damage these devices, however they may not meet all specifictions.  A minimum load of 10mA is required."  Okay, not clear and not complete, but the shunt resistor solves the problem by keeping the output current above 10mA.

The capacitor that I linked in my previous post is a fine choice for C1 and C2 shown in the spec sheet circuit that you show.  Buy ten of them, they come in handy.


The Fender Rhodes Electric Piano / Re: Key Pin replacement problems
« on: July 13, 2018, 05:18:10 PM »

On the 73-key plastic-key Rhodes, I thought the front rail sections are five sections of 12 and one 13.  I don't feel like unscrewing the rail and lifting all the keys to check for sure.  Maybe I am thinking about the balance rail, not the front rail.

I wonder if the 9-key sections would be for a 54-key Rhodes.

In any case, call Vintage Vibe and see if they have the sections that you need.  Their shopify website isn't always perfect, but they are good folks and will dig to find what you need.



I would not want to use an electronic device with zero documentation and zero warrranty and zero support.
I would not install this inside of an irreplaceable piano.

You can get thousands of DC to DC converters from Digikey or Mouser.  Fully documented, with warranty and support.

The 7809 regulator would indeed require a heat sink, and would run hot.  Modern switch-mode replacements are much more efficient, and can be quite tiny and inexpensive.

I personally like the tiny units from Recom, like R-78C9.0-1.0 (and R-78E9.0-0.5 if you only need 500mA).
You can comfortably touch this unit while in operation (I can't detect any temperature rise with my fingers.)

These work great for audio, as long as you make sure you have at least 10mA flowing.  With less current, the protection circuitry kicks in and you start getting audible hiccups... well, it is a steady buzzsaw sound.  So all you have to do is put a resistor across the output that will draw 10mA and create a tiny bit of waste heat (not anywhere near as hot and wasteful as the old analog/linear 7809 regulators).  If you put an 820Ω resistor across the output terminals, it will silence the output, and only waste 11mA.  In theory, you only need a tiny resistor (1/10th Watt), but you should use a big fat one to allow it to run cool (choose whatever you have on hand - 1/2W, 1W, or 2W).

I use a 10uF tiny little ceramic filter capacitor across the output, like


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