News:

Shipping now! "Classic Keys" book, a celebration of vintage keyboards  More...

Main Menu
Menu

Show posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.

Show posts Menu

Messages - maestro

#1
Some tools should be retired from the piano technicians arsenal, I cite the key bushing tightener because it is a destructive tool which only achieves its intended result by a brute-force, severely inelegant method.  You make inconsistent work for yourself, and you make future key-bushing replacement more frustrating for the next tech who deals with the board. You can replace felts until the cows come home, but it's really hard to achieve consistency on key mortises that have been bashed in by this tool, splintering and deforming the wood in the process.

VS Pro-felt (by PianoTek) can revive keyushings if they're not too far gone (read: threadbare). But getting into bushing work requires specialized tools and experience and you may be better off having a piano tech do the bushings for you, or better yet, replace the lot and give your piano a guaranteed few more decades of bushing-worry-free operation. A piano tech will have a good set of sized bushing cauls (not the spring loaded type) and heat-treating cauls to make each bushing extremely consistent one to the next.

Also, you showed a photo of a key with an out-sized balance hole. This takes some finesse to fix properly. The old style phenolic inserts are not available anymore, although you may be lucky to find a tech with some left overs plus the special installation drill-bit. However, this isn't the best approach as they can add noise to your keyboard. Ideally you outsize the hole, plug it with hardwood and re-drill. Locating the new hole needs to be very precise.  If you're lucky the original holes can be salvaged (I can't tell from the photo), I like to use Chair-Doctor glue to tighten and then a key-bushing reaming tool to widen to the correct size.  Again, you may want to consult a piano tech to help you with this process or give you guidance.

BAH. Not fun work. Good luck!
#2
4.7uf capacitor C5 and C8 are missing a polarity symbols on the schematic, which read as bipolar. However, the PCB does have polarity indicated. Which is in error?
#3
Sorry - not crossover point, my bad. I mean Crossover distortion.

I haven't removed the amp yet, so no testing/adjusting yet. I've never worked on the 140B amp, lots of experience with the 200 series though. On those amps I've replaced the driver transistors and rarely find that is a fix-all, I almost always need to adjust the R34/58 on those chassis to eliminate distortion.

This particular 140B is pretty bad for x-over distortion on the output stage (not present in line-out).
#4
Which resistors are responsible for setting the crossover point? I've done this on the 200A board but never on a 140B.
#5
Not sure what changed from last night until now but I was able to reduce R34 down to 205 ohm, parking the output stage voltage drop at 6-7mV. No crossover distortion. TR9 is at 50 mV and the amp output is at 30mV, idle with speakers disconnected. Thanks for sharing your thoughts!

#6
What if you can't find a middle ground between bringing the output back to 5-10mV and getting rid of crossover distortion?
#7
I've got a 200A which had some annoying distortion happening during note decay.

I replaced TR 9/10/12/14 without success. TR9 base was sitting slightly above 0V.

I then re-based TR 9 with 240 ohms in place of R34 (nothing in R58's spot). I did this by placing a pot in series with the original R34, 160 ohm, and found that I eliminated crossover distortion at 240 ohms total. Better yet, the TR9 returned to 0 volts and my voltages at the output transistors are reading a bit better than before.

The new issue, potentially, is that I'm reading 40mV across R37/38 whereas the schematic only calls for a range of 1-10 mV. The heatsink which previously ran very cool is now warm to the touch. Is this a problem?
#9
The Wurlitzer Electric Piano / Re: Wurli line out
March 03, 2012, 07:35:20 PM
This new line out is perfect! Especially in-studio as you get a super clean source to start with and treat however you like. I thought it was pretty damn nice through a Champ (single-ended 6v6, 5w), I have a similar circuit with master volume which I think should be a full time "preamp" (after the reed bar p/u). this is gonna be sweet.
#10
ba-boom. i'm running with this idea and ivorying up my 206.
#11
The Wurlitzer Electric Piano / Re: Wurli line out
March 03, 2012, 02:05:17 AM
I only mean to bypass some, not all of the electronics; specifically the amplifier modules.

low and behold, staring at the schematic for an hour reveals the answer to my OP. I'm 99.9% certain I can steal the signal between the preamp and aux/power amps. I'll let you know how it works out.
#12
did I say 70's? I was wrong...

From http://www1.american.edu/ted/elephant.htm

Threatened with extinction, the elephant is theoretically protected from international trade by their listing on Appendix I of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) since 1989... The total ban on the ivory trade came into effect on January 18, 1990... The United States was the first country to ratify CITES in 1975... On June 5, 1989, President Bush authorized a moratorium on all ivory imports into the United States...Before President Bush's 1989 ban, the United States was one of the largest importers of worked ivory in the world"

from http://www.worldwildlife.org/what/globalmarkets/wildlifetrade/faqs-elephant.html

"Since 1975, Asian elephants have been listed on Appendix I of CITES, which prohibits all international commercial trade in Asian elephants and Asian elephant ivory. African elephants were listed on Appendix I of CITES in 1990."
#13
The Wurlitzer Electric Piano / Re: Wurli line out
March 01, 2012, 11:05:40 PM
My 206 has two outputs, headphone; a powered output for the speakers padded down by an 8ohm/5W resistor, and AUX; an output added by the vintage vibe upgrade kit (vibrato + aux out).

The Aux out has never worked well - just a poor quality signal on both 206's i've been working on. It isn't distorting, the signal quality is simply reduced, perhaps 'low, yet noticeable white noise and poor frequency response' is the best way to describe it.

The padded power amp output works best for my applications (live use), but sometimes it acts up (strange noises that are too infrequent to have the issue start on command for a recording device).

I'm interested in bypassing as much circuitry as possible in the power module, even going as far as using an external preamp. Is this possible?

p.s. what is noise floor?
#14
Define "new" ivory...right off the elephant? or used up from bulk stock?
How can you spot a piano today and say whether or not the ivories were new at the time of installation in the factory?

Interesting tid-bit:
According to the Steinway & Sons biography, USA Steinway pianos saw the move from ivory to plastic in '63 or '65 (can't remember off the top of my head). purely a cost cutting move. there were no regulations of any kind until the 70s, also the Hamburg factory produced with Ivory for at least another decade). No mention specifically if the ivories were old or new but it did mention that they were factory bleached. (Is all ivory bleached, even straight off the tusk?).

This week I saw a 1972 Kawai 9ft grand with one piece ivories, very cool.
#15
FYI - Ivory regulation did not start until the mid 70's. Also some Asian piano makers (Kawai for certain) installed one piece ivories, not separate heads and tails.

I've seen a 112 before but did not notice the key top material.
#16
The Wurlitzer Electric Piano / Re: Wurli line out
March 01, 2012, 06:18:13 PM
Thanks for the info. A few questions - the "little passive box"...Can you describe it? I can't find it on their website. Does it go inside the piano or does it plug into the AUX output? Is its purpose to convert the high-impedance signal to a more useful level?

I'd like to solve the problem at the source if possible...(and avoid VV if possible) Using the built-in amp for the 2x8" speakers is great, but I'd like one clean-as-can-be output for studio use. For gigging I'm fine taking the headphone signal. Though, sometimes I get funny noises...

Where on the amp board can I tap a low level output? Any suggestions??

Thanks again
adam
#17
The Wurlitzer Electric Piano / Wurli line out
March 01, 2012, 10:44:46 AM
Ahoy,
I'm having trouble with getting clean line out signals from a pair of wurli 206's that have been updated to 200A specs. Is it possible to take the line out signal directly from the reed bar pickup?

Basically the headphone output is too dirty for studio use, and the main line out circuit sounds even worse.

Any help is appreciated!
adam
#18
Is the 110B germanium?
#19
If you are cross-referencing DTG-110B as the replacement, then yes, I can confirm that it is the correct replacement part (and only one that I know of). Unfortunately it is important to use matched pairs to prevent problems down the road, and getting them as a set is expensive. Your ebay find probably won't have these matched up, yes?
#20
I spoke with a electronics supply store today - DTG-110B is available (though only 1 of their major distributors carries it) and it is about $130 per matched pair and the rhodes uses two pairs...so this is a steep repair. The store said there were no cross-listed parts for this model number. Bummer.
#21
What symptoms would I hear from a suitcase suffering from bad output transistors?

Even with the keyboard unplugged from the amp unit, when powered up I hear intermittent static and loud popping noises, separated by a few seconds of silence.

I usually go into repair projects with the plan of simply replacing all suspect / time sensitive components, but the output transistors are expensive (Almost $300 for two matched pairs) and no other substitutions are listed.

Any help is appreciated
Thank you!

adam
#22
Ahoy!

I've had a Sparkle-top 69 Suitcase with Peterson equipment circa 1967 which was dropped off in need of some tlc.

The suitcase connector is 4-pin and is hard-wired at one end to the preamp. The harp output is good, but the amp doesn't play and does not respond to preamp controls - it instead - quite loudly - burbs up intermittent yet steady crackles and pops.

I have 3 schematics; preamp, power module and Power supply/regulator. I'm on the road for a few days but intend to check the voltages and tighten/clean all connectors when I get back.

I've read "Steve's Corner" on the rhodes site, but if anyone has additional tips, i'm interested in learning about other service issues which these old suitcases may experience. Also, aside from power section filters (if they haven't failed already), are there any special parts which should be changed as a matter of preventative maintenance? Lastly, what is the purpose of the trim pots located on the regulators and amp?

Much appreciated,
adam
#23
FYI there is a really cool product out called VS Profelt...

For plain lube jobs I still prefer ProTek.
VS profelt is a lube too, but works wonders to re-condition stiff or compressed felt. It is amazing stuff because it seems to expand lose felt but also lubes tight felt, and you end up with perfect action centers and key bushings.

If you soak the front rail bushing felts, use a caul spacer fitting and leave overnight, this stuff re-expands the felt without any negative side effects. You'd need a large collection of cauls to do the job with any efficiency but then again you'd need them for a re-bushing job anyway.

Just spreading the goods....
#24
They key-bender tool is worth its weight in gold (and it is heavy)...My friend worked at a machine shop and whipped one up for me, but this is a must have when replacing the pads as the hammer height will be all over the map - most of the pads will press the reed down beyond its resting point, encouraging mechanical noise when the piano is played, as well as uneven notes. The new pads are a fixed height, whereas the old sticky pads had a layer of foam built in and would compress over time.

Love the new sticky pads but a key height adjustment should not be overlooked
#25
The modern preamp leads me to believe that this is 200A. Why do you suspect the ID plate is not original? looks ok to me...As per low noise and pickup shield, just play it and see how it sounds!!

You're gonna pay $200 for a proper sustain pedal so make sure this is reflected in the selling price and the fact that it is not 100% functional.

If I were to buy this for a project I wouldn't spend more than $500-600, realizing that they fetch +/- $1000 in good condition when complete. The broken keys are most likely broken reeds ($20 a piece to replace) or something is broken in the action...but I'd guess broken reeds first.
#26
That sounds like a good idea.
I'd replace the 2 transistors and ALL the electrolytic caps, then go over the underside of the circuit board and re-heat all of the solder connections. 
Do you have a electronics supply store nearby? The parts are super cheap if you source them individually. digikey maybe a good place too...
#27
I'm no expert but this could even be a chopped student model 206 spray painted black.

Underneath the piano should be an ID tag.
Pics with the lid off may help as well - there may be a schematic on the underside of the lid.
Then again, with the lid off it should be easier to tell just from the amp, presence of speakers, reed shield...etc
#28
Take the bulb to radio shack?
Its some low wattage 120V lamp...possibly neon.
#29
Quote from: daswans on February 11, 2011, 01:01:15 PM
This looks great. I'd love to do this with my 206A. Any chance of giving us a step-by-step of the procedure?

Sure. Its quite easy.

1) Take everything apart. Leave screws inside their respective threads or place in small jars with a label to know where they go back. Below is an outline of the procedure but you should watch the youtube vids that are floating around.

Remove knobs, 5 lid screws, and lid.
Remove pickup shield, unscrew reed bar pickup
Unscrew the ground wire (in between the transformer and preamp) and disconnect the power and 9 pin molex connectors.
Remove preamp shelf.
Disconnect all the damper rod stickers from the dampers.
Disconnect the sustain rod (both by unscrewing the ferrule and removing the rod from the damper unit). Remove the 2 screws that hold the damper bracket to the back of the action. Also remove the screw which holds the two damper units together. Remove the two screws on either ends of the damper assembly and remove each side of the dampers one at a time.
Remove the action by removing the 5 screws, one at each corner and there is also one in the middle of the assembly.
Remove the keys (keep them in order!)

Now you can vacuum out the mounds of dust. leave the paper spacers under the keybed and don't suck up any of the spacer punchings or rail felts! Clean the keys while you're at it.

Unscrew the piano input/output box in the base. Cut the molex connector and pull all the wires out from the bottom (including the headphone jack). At this point you can separate the base by removing the 4 wood screws along back, two wood screw behind the key bed, and two machine screws from underneath at the outer front edges of the base. (You'll need to remove the speaker baffle, cut the speaker wires at the terminals for now). I chose to hammer in 6 balance rail pins into the existing wood screw holes in the base, and i'll keep the 2 machine screws in case I ever want the piano to be more secure along the front edge if the unit ever has a long term living room stint.

Pull out the white plastic insert from the center of the piano bottom. Plug the hole with a dowel and glue, in 24 hrs drill it out with a 1" spade bit, but don't go all the way through. Stop when you're about 1/8" to 3/16" from the bottom this is your new "AMP OUT" to the speakers. I used a jack with a switch. When no speaker is plugged in the switch routes the AMP out to the headphone jack which has resistors across it (re-use these from the 3 position switch)...the 8ohm 5W resistor goes across the + and - of the headphone jack, the other resistor (YL-V-GY) goes inline with the +. When the speakers are plugged in the headphone jack and padding resistors are disconnected. Place the Low A key back in the piano and again, with the 1" spade bit drill out another hole just in front of the headphone jack (towards the front of the piano) for a "line out" jack, stopping to make sure you don't go through the entire way.

Drill out a hole for a new AC receptacle..I think I used a 3/4" spade bit followed by small drills and a wood rasp. Install the latches with spacers between them and the base to keep them flush with the piano's back edge. That's about it! The piano can now be reassembled. For the speakers I used a normal 1/4" patch cord cut to a 2ft length, meeting the old speaker wires where I installed spade terminals, in case I need to open the bottom panel the line can easily be disconnected from the speakers. Don't hesitate to PM with questions...

I opted to leave the sustain pedal installed (as opposed to gutting it and building into a pedal box) and I'll eventually buy a proper 200A style when I scrounge up the cash for portable use.

cheers.

Steve i'll check on the action next week!

#30
Howdy,

have not checked the action yet, won't get to it till next week (btw, I've never adjusted the sticker height).

I'm not sure at all about your output jack positioning description, but the original headphone jack is on the underside to the left of the low A, and it has always worked. I drilled out a space for the line out jack just in front of it. The speaker jack is installed where the stock cables once passed through to the body.

Here are the pics...nothing fancy, just wanted to keep it looking like a 206.







Those latches are cheap and although the 2 halves look like they're installed far apart, it was the distance necessary to make a firm connection between the two pieces. They work quite well.
#31
But I chopped it, and kept all the jacks working, and added 2 extra jacks, 3 in total, AMP out, AMP out with headphone padding, and LINE out, installed with the VV vibrato kit...?
#32
OK, its finished.
Pics will have to wait for a few days.

The piano is so back heavy it could have worked without the rear latches, but i'm glad they're installed.

I've noticed this on another 206 vibrato upgrade - the line out is so dirty and almost unusable because it has so much hiss. I'm thinking of using the AMP OUT instead, padding it down with some resistors.

I also went ahead and tightened all the action screws, and i'm not happy with the results. The action is, pardon the obvious, much stiffer. Also a few notes don't reset properly (the jack doesn't move back to its starting position unless the key is struck with sufficient force. This makes softer playing more aggravating). This will have to be remedied soon!

Pics to follow...
#33
The Wurlitzer Electric Piano / Re: wurli ep dating
February 09, 2011, 12:13:20 PM
My bad, 206A.
F/C 1098018 (one speaker starts with F, the other with C).
No other codes on the speaker. 8018 "looks" like a date code, but 109 means nothing to my speaker mfg list.

thanks for the help everyone.
#34
The Wurlitzer Electric Piano / wurli ep dating
February 08, 2011, 12:49:43 AM
Model 206A
S# 141469
Stamps inside the piano:
keys near E3: 00421236
High C: K-60-6 66006
Action rail: "A-605", 040884
Speakers: 204582 (who is mfg "204"?)
Vol pot: 1378017

any help is appreciated, thank you
#35
I went ahead a dropped 6 balance rail pins into the base - so far so good. The point of these are to simply guide the piano to the correct location on the base, then keep it from sliding around. It's on, and its not going anywhere...unless it tips forward.

I'm going to install the AC receptacle into the proper location on the piano tomorrow, then reassemble and see how front-heavy the keyboard is. The harp should keep the piano steady (back-heavy), however I think that 2 briefcase latches (see above link) along the back of the piano/base will make the piano most sturdy. Steve, this is my plan to support the piano from tipping forward, as opposed to using front braces. I'm going for a very minimalist approach in modifications and keeping both units as close to stock appearance is the goal.

All things considered, that is, no plan before today, things are going pretty good!!
#36
One of the main problems of exterior latches is that the bodies of the piano and base are not flush on any side.

I still really like the balance rail pin idea. Alternatively, I could use spring clips of some sort...install the female end inside the piano bottom in the existing mounting holes, with male ends sticking up from the base, and the two halves snap together. Problem is I don't know how to explain the type of clip i'm thinking of. best I can think of are found on the hinged lids of some pianos and vintage electronic organs. OR, again, stick with the balance rail pins, but add something like this:

http://www.reliablehardware.com/briefcaselatches.aspx

to the back of the base, on spacers to keep it flush with the piano. This way there is minimal intrusion - the clasps are on the back of the base, not really noticeable, and the only mod to the piano is the addition of the top portion of the clasp...Hmmmm....
#37
Good day,

I've been contemplating rebuilding/chopping my 206 for quite some time now, until this weekend when I starting taking everything apart with no real final plan. I've rebuilt the power section of the amp and added the vibrato/line out circuits. The action is out and the keybed is separated from the base.

If I were to 'abandon ship' at this point I could easily put everything back together. However, at this point I am still interested in making a "chop" which can easily be connected to the base for living room use. The previous electronics have been removed from the base and my plan is to install a small 1/4" jack in the old through-body hole (where the factory wires passed through the piano). That way, when the piano is landed on the base, a quick 1/4" connection installs the speakers, and the stock sustain pedal screws into the piano.

My issue is mechanical connection between the base and piano. My original plan included replacing the 6 piano-base wood screws with balance rail pins so the piano can just fall into the correct position, however, I'm worried that the weight will not be evenly distributed, or at least, not back-heavy enough as to allow the piano to tip forward when played.

Ideas? Suggestions? help please!

thanks
Adam
#39
I found the speaker signal to be too hot when vibrato is added, ditto for the AUX out.

Instructions kind of suck though and management are no help.

#40
Any luck yet?

Adding to Sean's response, it is possible that the light bulb burned out.
#41
Key bushing tightener fixed 50% of the problem.
I placed 1/8" spacers underneath the front rail felts to help the downstroke reach the felt...that fixed the other 50% of the problem!
#42
Thanks for the input!
I've been away for a few days but have partially disassembled the rhodes (removed the harp, sustain mechanism, two damper sections and one hammer section w/ keys).

I'm going to try and get a good picture or short video of the action's profile view so you can help me decide if I should re-locate the bump mod.

Thus far i've collected these few observations:

- there is noticeable side-to-side movement which causes key clack when I intentionally move the keys laterally. When the piano was assembled I never really noticed this to bug me, but I assume I should correct this by re-felting the front rail bushings?

- the bottom/front of every key never comes in contact with the green front rail felts. Specifically the hammer won't let the back of the key rise any farther to promote front rail felt contact. This doesn't seem normal. The gap is larger than 1/8". This means the key dip is as large is possible since the hammer cam and pivot is whats stopping and absorbing all the key energy instead of the front rail felt. The key dip is roughly 7/16".

As per your suggestions; Regarding Key easing, i'm having a hard time convincing myself of this idea, as there is no stiffness found in the key stroke. If I raise the front of the key and let go it falls back on its own. If I lift the hammer, again, the key falls under its own weight. The weight of the released hammer is enough to raise the key back to rest height. Also I can't find any resistance at the hammer pivot points - they all move quite effortlessly.

For now i'm going to add 1/8" shims under the front rail felts and add paper spacers to adjust the keydip. Any more pointers would be appreciated. thanks again!
#43
I am trying to improve my '77 rhodes action. The keys feel sluggish - that is you have to press them down further than most models i've played before hearing the attack. There is a note on the harp - "action modified, 1983".

Currently, there is no felt on the bottom of the hammers, but the key pedestal (flat, no marcel) have 3/8" wide white felt (1/32" thick) and a 1/32" wooden nub at the forward end of the marcel.

Can anybody advise on what the mod could have been? My guess is there should be felt on the bottom of the hammers as well as on the marcel, so maybe the hammer felts were removed?

Any help decoding this mod is appreciated. I've been reading the repair section of the manual, but just wanted some input from this awesome forum.

Thanks!
adam
#44
It took a few tries but I think I figured out how to remove the action to get at the critical components. I was thinking about replacing the felt on the hammers because the sound is a bit dull. Not sounding so much like the Elepian video from  polyvoks. The output kinda sucks as well, very hissy.

I've recorded some sound via the headphone plug.


http://www.sendspace.com/file/wgk4aw

This is pre-regulation so i'm hoping to correct some tones and change felts.

Any suggestions on how to get better attack? The plastic hammers kinda suck but can't be replaced without major mods. I can remove the hammer felts easily, in replacing them what sort of thickness should i look for??
#45
Interesting!

From what i've read as far as clones are concerned - Honer Electra-piano covered the rhodes, and the Elepian copied the wurli. The portable Denon model is a hybrid of the two - notably it includes the pickup system of a rhodes.

I'll post pictures of my newly acquired Maestro soon. The pickup system is different - no wound coil pickups as found in the Denon. Instead there are two metal arms that are positioned at the outside edges of the reed head. I think it's the wurly DC pickup system because it hums and pops if you touch anywhere on the iron frame.

My model needs regulation, new felts, 2 reeds, otherwise its quite clean.
#46
Greetings,

Long time lurker, first time poster...

I am a new owner of this Maestro electronic piano and can't find any useful info about it (Harmony Central reviews / thin history...ie

http://members.lycos.co.uk/karenlbeck/vkmag/issue3/html/orher_eps.html


I have experience repairing rhodes/wurli's and hammonds but this little toy piano is boggling my mind. I'm in the process of taking it apart to correct the action, change felts, replace reeds (very very similar to wurli reeds...though i'm not sure if they're identical in thickness and length) but curious to know if anyone has had any experience with these awesome little keyboards before I get too far into it.

I can't afford a working wurli/rhodes so the maestro was a decent bargain at $150...if not for the rarity value (handful in existence? no more then a few hundred were built apparently), then for the mellow sound akin to the wurli, which i prefer to the rhodes, though they're both very nice ;)

If no one can assist directly, could you offer up other resources to explore?

Cheers.
adam