Yamaha CS15 pitch drift

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Yamaha CS15 pitch drift

Postby michael stein » Mon Jun 22, 2009 10:56 pm

My CS-15 has started drifting out of tune real bad about every 5 minutes. I am running it off of 120v even those it is supposed to take 110v? Could this be the reason for the drift? The room it is in now, since i noticed the problem, is a bit hotter then the one before.
Thanks,
michael
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Re: Yamaha CS15 pitch drift

Postby Sir Ruff » Tue Jun 23, 2009 2:49 am

Room temp should not affect it like that-those yamaha's are very stable. The fact that you are running it at a higher US voltage than the lower Jap voltage it requires would worry me though. Isn't there a switch in the back to change the voltage? The CS30 has one. Either way, I would stop using it until you get a proper voltage converter, and then see if there is a problem then.
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Re: Yamaha CS15 pitch drift

Postby blanik » Tue Jun 23, 2009 3:01 am

if your synth is marked 110V it means it'designed to work on North-American voltages, when electricity was spread across the continent (many moons ago) the voltage was 110V (you barely got 110V back then...) with time the lines and the electricity distribution system in general improved so now the average voltage in North America is 117V hence the common expression " 120V ", old items still marked for 110V generally work with no problem on 117V

Japanese power on the other hand is 100V (not 110V) and japanese items rated at 100V are at risk when fed the actual 117V...

i'm new at synths but not at electronics and a drifting oscillator voltage (which would cause pitch drifting) sounds a lot like a bad electrolytic cap somewhere in the power supply area (or maybe a bad transfo but i would check the caps before)
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Re: Yamaha CS15 pitch drift

Postby michael stein » Tue Jun 23, 2009 5:58 am

thanks,
The synth is marked 100v and when I got it I was told it would work fine without an adapter but I will get a converter now just in case. Just so everyone knows my friend bought this synth a year ago and it was still in the plastic. So the abuse of it being run at 120v has been pretty minimal and im geussing (hoping) there is no permanent damage there.
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Re: Yamaha CS15 pitch drift

Postby madtheory » Tue Jun 23, 2009 9:29 am

If it was unused then you definitely have some dried out electrolytic caps in there. Get in there and test all the main ones, and replace where necessary.
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Re: Yamaha CS15 pitch drift

Postby blanik » Tue Jun 23, 2009 10:57 pm

if it's bought from one of those ebay Japanese sellers watch out, often when there's a cool vintage synth for sale in japan they don't mention the voltage so i write to them asking and they always reply with "it'll work fine in north america" without mentioning what's actually written on the metal plate, i always have to insist in another mail and they reply "it's written 100V but it'll work fine in north america" that might have been true in the 50s-60s but not anymore... they just want to sell it quickly and don't care if the synth melts down the first time you plug it in [-X

like madtheory said if it hasn't been used for many years chances are that one/many caps have dried out (although it's rare in 70s japanese gear, their parts where of higher quality than american stuff from the same time... if you're lucky a simple power converter will fix your problem without even opening the synth
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Re: Yamaha CS15 pitch drift

Postby michael stein » Wed Jun 24, 2009 7:47 pm

where can I get a power converter I checked frys electronics but had no luck.
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Re: Yamaha CS15 pitch drift

Postby Steve Jones » Wed Jun 24, 2009 10:19 pm

I have come across pitch drift on these machines before, it was caused by tarnished pins on the inter-board connectors (the flat connectors that link all of the circuit board inside). You could try pulling each one off, putting some Deoxit on them and re-seating them (making extra sure that you put them back on with the pins aligned correctly). If they are really black you can clean the exposed pins gently with a soft white pencil eraser and then wiping with alcohol before applying the Deoxit. The connectors on the SSK board on the bottom of the unit on the left are especially prone to this.

As for power, I would get a tech or someone that knows about electronics to check first, the general export model had multi-tap power transformers with taps for 100V, 110V and 130V, The Japanese model was only single tap at 110V and the US/Canadan a single at 120V. It would be worth checking inside to see if you got lucky and it is a general export unit and they can move the wire or replace a link to the 110 V tap which should be fine in the US. If there are muti-taps the voltages will be stamped on top of the transformer, or written on the circuit board. Take a digital photo of the transformer and power supply board and post it here and we can take a look.

The usual caveat applies, do not touch any mains section of your synth unless you are qualified and know what you are doing, and remove the mains plug from the wall before opening the top.
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Re: Yamaha CS15 pitch drift

Postby blanik » Thu Jun 25, 2009 2:31 am

michael stein wrote:where can I get a power converter I checked frys electronics but had no luck.
Thanks



sadly most busted electro caps won't show external signs of it but an experienced electronics technician will know where to check first...


the connectors pins like steve jones mentioned is a good first step
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