Yamaha Piano pedal mechanism

Google for a servo potentiometer, or a conductive plastic potentiometer. They are expensive, but are mechanically strong and have a live of milions of cycles.

On 8/25/2009 9:12 PM Sylvia Else spake thus:

You don't actually spell that thing "-metre", do you? Please tell me you don't.

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Found--the gene that causes belief in genetic determinism

It's not unusual to find pots in such applications, and there are types which are specifically designed to have very long mechanical lives. Using a pot keeps the circuitry simple. As an alternative, many guitar effects pedals use an optical arrangement instead, where a shaded or shaped 'shutter' mechanically connected to the pedal, passes between an LED and a phototransistor or diode, the varying DC resistance of the device caused as a result of this, serving as the equivalent of the varying resistance of your pot.

Arfa

By "you", I presume you mean people in my part of the world.

In truth, no, but why would it worry you if we did?

Sylvia.

The latter seems a beter solution. Take a typical piece of Piano music - Beethoven's well known "Moonlight Sonata" - it involves about 60 pedal cycles. Apart from wirewound (and horribly expensive) pots, the best I've found claims 100,000 cycles. I'd get through that in a year and half, easily.

Sylvia.

So how long has the original lasted ? If it seems to have done reasonable service, would it not be best to just replace it with a genuine one from Yamaha ? They are very experienced in the field of keyboard instruments, and I would have thought that they knew what they were doing in terms of best cost / performance ratios when choosing components for their designs. The only alternative that I see, is to use one of the 'horribly expensive" types to improve on the original specification. If you are that bothered about the lifetime of the standard device fitted, and having to replace it periodically, then I would have thought that the one-off additional cost was worth it ?

Arfa

Probably just needs a good cleaning. I own an old Yamy pedal. Used it with my Kawai keyboard for decades.

Gee, I'm shocked. Replace it with a wirewound version - if you can find one.

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    W
  . | ,. w ,   "Some people are alive only because
   \\|/  \\|/     it is illegal to kill them."    Perna condita delenda est
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Decades ago, on a Lowrey organ IIRC, I saw a lamp and a photocell used in the expression pedal. The pedal actuated a plate with a slot cut in it. The plate separated the 2 devices; the slot expanded from a slit at one end to wide at the other. No noise from the device and wear wasn't an issue.

...since the bean counters get the last word on what components go into the final product.

Think about a guided missile constantly being buffeted out on the wing of an aircraft and the sensing devices in that. It's all about specing the device for the job.

...but not uncommon.

At least Yamaha are willing to supply just the pot. I was expecting them to want to supply a complete replacement pedal mechanism, at some exorbitant price.

Spares guy described it as a "volume" pot for the sustaining pedal :)

None in stock here, though - order from Japan - takes 4 weeks.

So much for supporting their product.

Sylvia.

Which Yamaha model piano? Most Yamaha pedal mechanisms made in the last 20 years have been optical, not mechanical. For example:

"# Interference-free optical key, and pedal sensors"

"Sustain and shift pedals are equipped with continuous-position digital optical sensors"

Ummm... thanks for not calling it a rheostat.

This FC-4 piano pedal?

If so, I also have one. The one I've been using on my Korg DSS-1 has lasted about 15 year so far. I haven't had to tear it apart yet, so I don't know if it's optical or a pot.

However, I do have one problem with the FC-4. Despite the anti-slip rubber tread on the bottom, it still manages to slip around the carpet. I keep wanting to bolt it to a piece of plywood, but never have bothered.

Why on Earth would I do that?

It's the sustaining pedal on a 7 year old CLP-970. The sensor looks for all the world like a pot.

Fortunately, the CLP-970 is heavy enough to require two people to lift, so there's no problem of its moving around.

Sylvia.

Because it really is a rheostat. Officially, if there are three wires involved, it a potentiometer. If there are only two, it's rheostat. Since my FC-4 has only two connection on the phone jack, it's a rheostat. However, the internal variable resistors in the non-optical pedal mechanisms I've seen, use 3 wires.

Unfortunately, just about everyone uses these terms interchangeably.

Release data is Jan 1, 2000 which makes it at the bitter edge of when Yamaha started using optical pedal mechanisms. It doesn't specify the pedal mechanism, but only says "Half pedal effect (Right)" which makes me wonder why they bothered to use a pot instead of two switches.

Well, yeah. The pedals are part of the cabinet.

I'm rather surprised that you opted to get the original part from Yamaha. Potentiometers are fairly generic and available. If you have the old part, try to determine the taper (linear, log, audio, weird, etc), and the value of the pot with an ohms-guesser. Also the shaft type. Then go shopping online for a suitable replacement. If you need help, do some measuring and supply a photo.

**How old is it? Beyond 7 years (or is it 5 now?) they don't have to do diddly about spare parts supply, if they don't want to. Just appreciate that they can get you the right part in 4 weeks. I could tell you stories about ather brands, whose products have only been on the market for less than 2 years and the parts are NLA. Yamaha, IME, are one of the better companies for spare parts support.

OTOH, let your fingers do the walking and look through the Farnell cattle-dog. They have some very superior quality parts, which you may be able coax into the right spot.

--
Trevor Wilson
www.rageaudio.com.au

It has three. Five volts on side. Zero on the other. Middling in the middle. This presumably reduces its sensitivity to track wear.

I was looking at sourcing online yesterday. But the pot's in a quite restricted space, has an anti-rotation tab, and specific requirements on the position of the flat on the shaft (maybe that's standard). Also, I was quite unable to get a stable reading on the resistance from the centre connection to either end, even after soldering wires to it - presumably because of its wear. Also, it's impractical to make (presumably voltage therefore) measurements in situe - the pedal requires too much force, so I'd have to pull it out, and then either put it back (it works most of the time), or do without for however long it takes to source a replacement.

If Yamaha had offered me a replacement pedal unit for $lots, I'd have taken a second look, but for about $25 including postage, I get a replacement that's guaranteed to fit. Finding a substitute would likely be more trouble that it was worth.

If the replacement fails before the piano definitively dies, or I do, then I may look at retrofitting an optical sensor. I really only need on/off. The pot's used for "pitch bending" which is not something I use.

Sylvia.

From the ACCC web site

"What is ?reasonably available? will depend on the particular circumstances, such as the nature of the product and its expected useful life. There is no minimum period for a manufacturer or importer to provide facilities and spare parts for repair. However, a manufacturer or importer will remain liable for damages for up to 10 years if the failure to provide repair facilities and parts is found to be unreasonable."

This is a piano we're talking about, not an iPod. It cost not much shy of $5000 seven years ago. I'd be surprised if a court found that it was reasonable to cease supplying parts so soon.

Just appreciate that

Maybe, though when I went through Farnell's site yesterday, and considered the mechanical requirements, I couldn't find anything suitable.

Sylvia.

Nope. The mechanical wear is all mechanical. Looking at a typical spec sheet for commodity cermet potentiometers, I'm finding cycle lifetimes from 100,000 to 1,000,000 cycles.

Someone suggested wirewound. Bad idea as they're only good for perhaps 10,000 cycles:

I'll assume you tried lubing and cleaning it. If sealed, find a way to open it. If it's a square pot, drill out the rivets and replace them with 0-80 screws and nuts (or a piece of brass rod with the ends smashed to form a rivet.

You're not supplying enough info to find a suitable replacement. End to end resistance. If the voltage is half at midpoint, it's a linear taper pot. The rest is mechanical. Anti-rotation tabs are standard. The flat is usually where the screw goes on a know, which is on the OPPOSITE side of where the arm would be pointing. If it's what I'm guessing this is, you should have no problem finding a replacement. Photo?

Well, that's why I have a well stocked junk box, some old devices to cannibalize, and friends with an equal or greater mess of parts.

Sorry. I assumed it was the damper. I wouldn't imagine the pitch bending (portamento) control to be so heavily used as to wear out. Something else is probably going on. It could be a defective pot, but might also be some other type of failure. If the terminals are available, you might want to temporarily attach an electrically similar pot to the leads and see if it works.

It's the same pedal - just used in a different mode. If you want both functions simultaneously, you have to buy another pedal.

Sylvia.

In all fairness, they make the basic available at a reasonable price. That's way more than most manufacturers do for old products.

--
    W
  . | ,. w ,   "Some people are alive only because
   \\|/  \\|/     it is illegal to kill them."    Perna condita delenda est
---^----^---------------------------------------------------------------