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Old 25th Nov 2021, 10:02 pm   #1
llama
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Default Yamaha PDP-100 digital piano

Most of the keys are fine but a few need quite a hefty press to make their sound. I suspect dirty contacts in the velocity-sensing area but before delving into the innards I wondered it anyone else has had a similar experience and could point me in the right direction, please.

Underneath there are two panels that run the full length (4 feet!) of the piano - one beneath the keys and the other containing the speakers. It'd be useful to know which of these two would give best access to the contacts (if that's even a sensible question!).

Grateful for any pointers.
Thanks in advance
Graham
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Old 25th Nov 2021, 10:25 pm   #2
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Default Re: Yamaha PDP-100 digital piano

Since you are asking for specific information I think it's OK to post this, if not then mods please remove.

https://www.ebay.co.uk/itm/Yamaha-Pe...-/254189894249

In the USA unfortunately, but you might consider it worth the wait / outlay.

I don't know if it is still the case but Yamaha UK used to be superb for technical support and parts and may still be able to sell you a copy of the service manual, either an original paper copy or a PDF. They are known for supporting their products for a long time after the date of manufacture.

I didn't find a downloadable copy of the service manual in the short time I spent looking but I did spot one obvious scam attempt which would have required you to enter your credit card details to 'verify that you are not a bot' before letting you get to the 'free download' stage. Please don't fall for that one.
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Old 26th Nov 2021, 8:00 am   #3
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Default Re: Yamaha PDP-100 digital piano

I fixed mine a few years ago and took loads of pics which Im happy to share.

my problems were caused by a spider!
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Old 26th Nov 2021, 10:47 am   #4
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Default Re: Yamaha PDP-100 digital piano

Thanks for the responses.
Yes please, Nick. I'm about to release the 3 screws at the top of the back in the hope that that gives sufficient access to see/clean the contacts.
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Old 26th Nov 2021, 11:00 am   #5
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Default Re: Yamaha PDP-100 digital piano

The pics are on my PC at home, but if you remind me, I'll post them over the weekend.

I think quite a bit of dismantling is required. Nothing too tricky but the keyboard assembly is very long, bendy and fragile. I carefully lifted it out and put it on my (specially-cleared) desk for safety.
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Old 26th Nov 2021, 11:28 pm   #6
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Default Re: Yamaha PDP-100 digital piano

usually with yamaha you'll need to remove the keyboard chassis entirely from the cabinet and flip it over, remove the key contact pcbs and clean them. The keyboard will be held by a mixture of locating woodscrews and hefty machine screws sometimes accessed from under the cabinet.
9 times out of 10 though, poor key action is caused by worn conductive rubber contacts which are on strips beneath the pcbs.
Put plenty of time aside to do the job!
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Old 2nd Dec 2021, 6:01 pm   #7
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Default Re: Yamaha PDP-100 digital piano

I removed the 3 screws along the back-top and that allowed the top to be slid forward about an inch and then lifted clear. The insides are rather nice, but the top off doesn't give much access to any of the key components.

Three screws hold the next item in place - I'd call it the control panel. Actually I had to remove the middle strut from the base chassis before I could release it from the middle of the control panel but it's as well being completely off. When the cable-ties are loosened the control panel sits across the 2 speakers quite well, with card insulation.

The top note is a stand-alone key but unscrewing the long (M3?) screw at its rear only allowed it to move back and forth, not out. So I've removed the small metal bar to its right to see if more is visible - so far, not much.

I'm not sure the whole keyboard assembly comes out as a single lump but no doubt some more dis-assembly will reveal what's what.
Graham
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Last edited by llama; 2nd Dec 2021 at 6:03 pm. Reason: Added moving of control panel
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Old 2nd Dec 2021, 9:00 pm   #8
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Default Re: Yamaha PDP-100 digital piano

Both of the closing-pieces to the left and right of the keys needed to come out - the one on the left has the mains switch so that's now pushed to the rear for clearance. There are 6 screws, possibly M4, that hold the keyboard main plastic frame onto the bottom of the case. I thought that lifting it clear at the front would provide enough clearance to get at the contacts. I can certainly see them but I cant get that top note out so it looks like I'll have to remove the bottom steel plate with its 30 or so screws and then access the contact PCBs.
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Old 2nd Dec 2021, 9:42 pm   #9
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Default Re: Yamaha PDP-100 digital piano

Here are my rough notes from when I did a similar model, the CLP-810S:

Quote:
Remove top cover: 3 Philips bolts at rear, cover slides forwards and off.

Remove black metal plate at back of keys: one black ST screw at each side, note LH has earth tag and that wire from PCB to controls is tied to it.

Remove LH contols: Push back to release clip at front, tuck out of way near LS.

Remove RH power switch, as above.

Release KB: 2 woodscrews into MDF, several red-gold washered bolts. Lift up front and unplug blue loom from main PCB.

Remove KB: hold at front and rear (not left and right) and lift out.

Remove PCBs from KB: Remove several silver screws, hinge up and pull front edge out from under clips.

Replacing PCBs onto KB: Ensure there's no pressure from keys on rubber contact membrane. May need to prop-up KB vertically, pull-up every key, then install PCB.
Graham, PM me your e-mail address and I'll send you some more very useful info
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Old 2nd Dec 2021, 10:41 pm   #10
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Default Re: Yamaha PDP-100 digital piano

Thanks Nick - PM sent.
Meanwhile, I am leaning the keyboard back with soft tissues to avoid harsh contact with the control panel. I've removed the 20 screws that hold the steel plate on. Lots of dust.
A couple of multiway connectors are now off and the (two) contact PCBs are simply held by clips at the "bottom" that simply press down and allow the PCB out of the rigid plastic clips at the "top".
Lots of muck and a couple of dead spiders.
I'll clean the printed contacts on the PCBs but Kevin, do you happen to know if I should try and clean the conductive-rubber contacts that are pressed by the keys?
Graham
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Old 3rd Dec 2021, 12:17 am   #11
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Default Re: Yamaha PDP-100 digital piano

it wont do any harm but I think I would replace the lot, they aren't normally too dear. When they wear out, normally around the middle keys, they either go intermittent and dont play, or, embarrassingly can sound the odd note as though you'd hit it at full pelt. The les dawson act does not always go down well during a public performance..these days.
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Old 18th Dec 2021, 9:40 am   #12
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Default Re: Yamaha PDP-100 digital piano

Thanks again Nick - that's very useful information.
The pairs of contacts on the PCB cleaned up rather easily - I think I used "floppy disk head cleaner" with cotton buds. The conductive rubber pads (2 per key) mostly looked clean and rather than rub away some conductive surface I only touched the visibly grubby ones.

I couldn't get all the keys to be in their "up" position in order to refit the contacts PCBs so I placed 2 little stacks of RTVS books about 4 foot apart on the floor and rested the plastic keyboard upside down with just the ends supported. (That's about the most those books have been used in recent years!). The 2 contact PCBs went in quite easily with the fixed plastic lugs away from me and the flexible ones towards me. I was able to click the board back into place, one flexible lug at a time, using a small screwdriver on each to ease it in. One of them didn't seem to want to spring back but pressing it from behind gave a satisfactory grip.

Next step was to rest the keyboard assembly back in the piano case such that I could re-attach the two multi-way connectors. That needed to be done before fitting the steel plate back on. All 20 screws for that were put in loosely and then fully tightened - some are in slots, a few in circular holes. Then the keyboard was replaced in its correct place and carefully tested. All well.

So the 6 screws (M4 - ish) were screwed up into it from below. Then the two side blocks (one screw each) followed by the control panel. Its middle support has a couple of woodscrews into the piano base and one screw at the centre of the control panel. I dressed the cables into more-or-less their original places and the lid popped back on. Another brief testing session - no metronome, but I haven't tried very hard on that yet and haven't tried the two pedals yet.

Happy with the results so far and thanks again everyone for the helpful tips.
Graham
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Old 18th Dec 2021, 12:54 pm   #13
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Default Re: Yamaha PDP-100 digital piano

This thread might inspire me to open up my Yamaha stage piano which buzzes from time to time on specific notes.
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Old 28th Jan 2022, 1:40 pm   #14
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Default Re: Yamaha PDP-100 digital piano

Not to say that you won't get constructive answers here as well, but you might get a wider range of informed opinion from this forum,

https://yamahamusicians.com/forum/

..where the forum members are primarily musicians rather than retro technology enthusiasts.
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Old 28th Jan 2022, 2:50 pm   #15
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Default Re: Yamaha PDP-100 digital piano

Ray, from the point of view of learning, i think it's far better to learn on a 'real' piano if that's at all feasible. It's not the sound quality that's the issue, it's the tactile input from you, the piano player.

Doing things the other way round is a hazard to the angle of your learning curve, a good analogy would be learning to drive with an automatic gearbox....or learning to type on a modern keyboard then trying to type on a mechanical typewriter.

If you have no ambition to play an old school piano (or the step-change in learning curve doesn't bother you) then you can obviously ignore everything i have typed..!

Dave
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Old 28th Jan 2022, 6:16 pm   #16
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Default Re: Yamaha PDP-100 digital piano

Dave, as someone who (albeit a long time ago) managed a distinction in grade 8 piano, I have to say that the better digital pianos are actually very hard to tell from a decent acoustic piano, from a player's and listener's point of view.

They have full-size, touch-sensitive, weighted keys and playing one feels like playing a proper piano in almost all ways. Certainly nothing like a "keyboard" or an "electric piano" of days gone by. Trying to learn the piano on one of these certainly would have been a mistake.

They have a precision that a typical hand-me-down, 100 year-old domestic piano lacks, which is a double-edged sword; the downside being that when you go back to typical normal piano, a few things that you can play on the digital piano prove to be almost impossible (especially fast passages with repeated notes).

I was sceptical at first, and would never be without our 1880s Bluthner upright, but as a general purpose instrument, they're great. They sound good, they feel good to play, they take up very little space, they can be moved around at will be one (strong) person, they can be moved from house-to-house in a normal car, they don't need tuning, and so on. I have two: one cost about £1k 20 years ago, the other (almost identical) cost £75 in a charity shop a couple of years back.

OTOH, they usually look hideous without any of the aesthetic appeal of a real, vintage piano, and they can be impossible to fix when they go wrong. They're also responsible for a lot of decent acoustic pianos literally being thrown away; I've been offered three in the last year (including a nice 1930s grand from one of the University colleges), with the threat of them having to be destroyed if nobody wanted them, but was unable to accept any of them due to living in a modest 3-bed semi.

N.
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Old 28th Jan 2022, 6:46 pm   #17
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Default Re: Yamaha PDP-100 digital piano

That's interesting Nick.
My other half has a Yamaha PSR170 which i briefly played with last week, the piano sound effect (the only effect that i tried) was extremely good, and the unit without batteries weighs virtually nothing. She claims it originally came without a mains adapter, (?) and was just about to test it using one of those adjustable wall-warts set to 12v- knowing how unregulated they are i stalled her and managed to find a 9.5v 1,400mAh adapter of the correct polarity, which i reckoned would be a much better bet.
I think that my Mum got to grade 8, but has since given away her piano to my sister and now only has a two pedal keyboard at home!
Dave
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Old 28th Jan 2022, 9:23 pm   #18
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Default Re: Yamaha PDP-100 digital piano

some of the digital pianos use actual acoustic piano hammer actions but with electrical contacts. The rubber contacts on these are particularly fiddly to replace as you have to dismantle each key & hammer individually, and, like a real piano, are weighted differently depending on which end of the keyboard you're dismantling. You have to pay attention when replacing them.

I'd have no qualms buying a good digital piano for home, they stay in tune permanently, offer a choice of sounds (even other keyboard instruments like a harpsichord!) and can be used with headphones. They will usually fit in the back of an estate car too, although the digital grands are somewhat bulky if you don't have the use of a volvo.
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Old 28th Jan 2022, 10:43 pm   #19
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Default Re: Yamaha PDP-100 digital piano

Modern digital pianos are virtually indistinguishable form the real thing for most people, as for the key action that now is also just as good as a real piano with some emulation the escapement action and Yamaha even has one that adds vobration to further enhance the feel.
Also in some cases a digital piano actually has a stiffer action than an acoustic piano, so not always is playing on a digital piano easier.

If you want to get an idea about what the different models sound like then Thomann (www.thomann.de) have their own audio samples on their product pages from the pianos in question.
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Old 29th Jan 2022, 2:48 am   #20
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Default Re: Yamaha PDP-100 digital piano

The Yamaha PSR range aren't really representative of modern electronic pianos Dave. The 170 has a very basic keyboard action that isn't touch sensitive, let alone properly weighted. However, it has a reasonably decent sounding grand piano preset (or at least the almost identical looking PSR175 does) and it responds properly to velocity via MIDI so at a pinch it could be partnered with a weighted MIDI keyboard to give a more realistic feeling piano.

I had a 30 year old Korg C15 digital piano in for repair last week and I would have to say that, while the weighted keyboard felt good to play, the sounds were very disappointing compared to the more modern cheap Yamaha PSR keyboards. I would expect the modern dedicated pianos to be even more impressive.
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