Yamaha CS-20M: fried [edit]

Pulling out your hair? Don't know what to do or where to go? Ask in here.
Forum rules
READ: VSE Board-Wide Rules and Guidelines

If your Help request has been solved, please edit your first post in order to select the Image Topic Icon to let others know your topic has been solved.
User avatar
fh991586
Senior Member
Senior Member
Posts: 972
Joined: Sun Sep 26, 2010 10:20 pm
Real name: Francis
Gear: Roland JX3P, D50, U220, MVS1, JP8080.
Korg Kaossilator, Monotrons, MicroKorg, M3R.
Yamaha Motif Rack.
Midines
Location: French Canada

Yamaha CS-20M: fried [edit]

Post by fh991586 » Sat Oct 01, 2011 4:43 am

Hi there!

I recently purchased a Yamaha CS-20M, knowing that it didn't have sound coming out of it. But since it powers on, I figured I could give it a try anyway... After reading the manual, and opening it to do a visual check, it seems that the unit is stuck in load or store mode, so the sounds from the panel are not activated. The manual states that you can shut it off to get back to the panel mode, but it doesn't work in my case. Anybody knows what to do? The LEDs over TRIGGER, LOAD (2nd one), STORE, WRITE & PANEL stay on.

Anyone ever encountered this on a CS-20M or a CS-40M?

The only thing I know from the previous owner is that it worked well before he left it in storage for a long time, and the 2AA batteries leaked inside. But it's in an enclosure under the synth, not inside near panels where it could touch anything: the leak left residue on the springs and the cover plate, but I scrubed it.
Last edited by fh991586 on Fri Oct 14, 2011 5:12 am, edited 2 times in total.
Considering parting away from:
-Roland TR707
-DSI Mopho

User avatar
fh991586
Senior Member
Senior Member
Posts: 972
Joined: Sun Sep 26, 2010 10:20 pm
Real name: Francis
Gear: Roland JX3P, D50, U220, MVS1, JP8080.
Korg Kaossilator, Monotrons, MicroKorg, M3R.
Yamaha Motif Rack.
Midines
Location: French Canada

Re: Yamaha CS-20M stuck in load/store mode (no sound)

Post by fh991586 » Sat Oct 01, 2011 4:09 pm

Upon re-checking inside, I finally noticed there's a blown 250V/500 mA fuse (2 are inside, and a 250V/750mA is outside near the power cord entry). But impossible to find a store in my area that still sells those! :x I clearly remember buying some at Circuit City (then Radio Shack) 10 years ago for my stereo system, but they don't sell this kind of parts anymore (god damn cell phones everywhere, though!)...

As soon as I can find a specialised electronic parts store (like Addisson, if not nearer), I'll be able to tell if that was the only cause of my problem.
Considering parting away from:
-Roland TR707
-DSI Mopho

User avatar
rhino
Supporting Member!
Supporting Member!
Posts: 2610
Joined: Sat Aug 02, 2008 5:00 pm
Real name: bill
Gear: keepers:
Kurzweil K2500x
Ensoniq TS-12
Yamaha SY-99
Alesis QS-8
Roland JD-800
Roland JX-10
Akai AX-80
Ensoniq SQ-80
Korg DSS-1
Moog Mini
Fizmo
Location: kentucky hills

Re: Yamaha CS-20M stuck in load/store mode (no sound)

Post by rhino » Sat Oct 01, 2011 5:10 pm

Where are you? Radioshit has the 500 ma (1/2 amp) fuses here in Richmond KY. you could get by with a 1 amp to replace the .75 one

BUT !!!!!! First thing you should do is replace the Tantalum (sp?) by-pass caps. They short with age and if they are used to de-spike the power rails, they will blow the fuses at once. Same thing on my CS20m.
When the wise man points to the stars, the fool looks at the finger.
- Confucius

User avatar
fh991586
Senior Member
Senior Member
Posts: 972
Joined: Sun Sep 26, 2010 10:20 pm
Real name: Francis
Gear: Roland JX3P, D50, U220, MVS1, JP8080.
Korg Kaossilator, Monotrons, MicroKorg, M3R.
Yamaha Motif Rack.
Midines
Location: French Canada

Re: Yamaha CS-20M stuck in load/store mode (no sound)

Post by fh991586 » Sat Oct 01, 2011 7:03 pm

Thanks for the advice, but too late... A couple seconds after powering the unit upon changing fuses, smoke came out of the dash. :cry:

Image

Is this fixable?
Considering parting away from:
-Roland TR707
-DSI Mopho

User avatar
rhino
Supporting Member!
Supporting Member!
Posts: 2610
Joined: Sat Aug 02, 2008 5:00 pm
Real name: bill
Gear: keepers:
Kurzweil K2500x
Ensoniq TS-12
Yamaha SY-99
Alesis QS-8
Roland JD-800
Roland JX-10
Akai AX-80
Ensoniq SQ-80
Korg DSS-1
Moog Mini
Fizmo
Location: kentucky hills

Re: Yamaha CS-20M stuck in load/store mode (no sound) Ed: Fr

Post by rhino » Sat Oct 01, 2011 11:16 pm

ANYTHING is fixable (well....then again...)
Talk about a hot chip !!
Let me get out the schematics...
When the wise man points to the stars, the fool looks at the finger.
- Confucius

User avatar
fh991586
Senior Member
Senior Member
Posts: 972
Joined: Sun Sep 26, 2010 10:20 pm
Real name: Francis
Gear: Roland JX3P, D50, U220, MVS1, JP8080.
Korg Kaossilator, Monotrons, MicroKorg, M3R.
Yamaha Motif Rack.
Midines
Location: French Canada

Re: Yamaha CS-20M stuck in load/store mode (no sound) Ed: Fr

Post by fh991586 » Sat Oct 01, 2011 11:34 pm

Thanks! The easiest way would be to get a full CS-20M PGM board to switch with mine, but it might be difficult to find nowadays... ;)

I can't read the writings on the chip, but the spot is identified as IC8. Nothing around looked damaged after I removed a little of the black burnt traces on the board. The underside seems ok too: just a hint of darkened area beneath the green circuitry.

My main inquiry is why it burnt? Was is the chip itself who gave up? Was is the new fuse which wasn't good (defective item or wrongly identified)? Or any other defective part causing a short that focused on that chip? I don't know what's the IC8's purpose on the board, so I can't tell if it was related to the problem I was refering in my initial post.

Of course, I'm in no hurry to deal with this, so don't sweat finding it. The rest of the synth is in great shape, so I would really like to make it work again. If you discount the usual manipulation dirt on the panel, I believe it was well cared for over the years. If I have to junk it, all the other parts would be great assets in their present shape.
Considering parting away from:
-Roland TR707
-DSI Mopho

Steve Jones
Active Member
Active Member
Posts: 565
Joined: Wed Apr 23, 2008 10:40 pm
Real name: Steve
Location: Sydney
Contact:

Re: Yamaha CS-20M stuck in load/store mode (no sound) Ed: Fr

Post by Steve Jones » Mon Oct 03, 2011 11:19 am

Looks like an op-amp with an internal short. Not uncommon, an easy and cheap fix. Your front panel issue may have been due to the missing power rail cause by the popped fuse. Replace the chip and the fuse and see what happens. Don't worry, the machine is fixable.
Synthesizer service tech since 1982.
Synth parts and service, Sydney Australia.

User avatar
fh991586
Senior Member
Senior Member
Posts: 972
Joined: Sun Sep 26, 2010 10:20 pm
Real name: Francis
Gear: Roland JX3P, D50, U220, MVS1, JP8080.
Korg Kaossilator, Monotrons, MicroKorg, M3R.
Yamaha Motif Rack.
Midines
Location: French Canada

Re: Yamaha CS-20M stuck in load/store mode (no sound) Ed: Fr

Post by fh991586 » Wed Oct 12, 2011 1:35 am

So, anyone can tell me which chip I should be looking for? That's pretty much the first step I can think of doing...
Considering parting away from:
-Roland TR707
-DSI Mopho

Steve Jones
Active Member
Active Member
Posts: 565
Joined: Wed Apr 23, 2008 10:40 pm
Real name: Steve
Location: Sydney
Contact:

Re: Yamaha CS-20M stuck in load/store mode (no sound) Ed: Fr

Post by Steve Jones » Wed Oct 12, 2011 1:41 am

Which board has the burnt chip on it? It's IC8, if you tell me which board it's on I will look at the schematic and tell you what the chip is and where to get it.
Synthesizer service tech since 1982.
Synth parts and service, Sydney Australia.

User avatar
th0mas
Expert Member
Expert Member
Posts: 1349
Joined: Thu Jul 14, 2005 5:27 pm
Gear: oakley tm3030/mopho keys/midibox sid/tr-707/tama techstars/monotron
Band: GRAVITRONIC
Location: Ontario
Contact:

Re: Yamaha CS-20M stuck in load/store mode (no sound) Ed: Fr

Post by th0mas » Wed Oct 12, 2011 2:12 am

Where did you buy this? Reminds me of one I sold into quebec.. at the time it'd blow fuses and I didn't have the time to fix it. I'd start by rebuilding the entire powersupply as it continually blows fuses.

Tom

User avatar
synthparts
Senior Member
Senior Member
Posts: 779
Joined: Sun Oct 09, 2011 12:05 pm
Location: SF Bay Area, CA
Contact:

Re: Yamaha CS-20M stuck in load/store mode (no sound) Ed: Fr

Post by synthparts » Wed Oct 12, 2011 3:33 am

IC8 is an NEC 271C "precision voltage comparator". I have one, send me a PM if you want one. You first should replace all the tantalum caps though if you don't wan't it to blow again.
Vintage Synth Parts - http://www.synthparts.com

User avatar
fh991586
Senior Member
Senior Member
Posts: 972
Joined: Sun Sep 26, 2010 10:20 pm
Real name: Francis
Gear: Roland JX3P, D50, U220, MVS1, JP8080.
Korg Kaossilator, Monotrons, MicroKorg, M3R.
Yamaha Motif Rack.
Midines
Location: French Canada

Re: Yamaha CS-20M stuck in load/store mode (no sound) Ed: Fr

Post by fh991586 » Wed Oct 12, 2011 12:58 pm

I'm in Montreal, and I've never seen another CS20M on the market in the last 2 years so maybe the seller wasn't totally square with me regarding its origins (the musician's studio is on Parthenais street)...

I have no idea what tantalum caps are, so I guess I should bring it to a tech to do the whole job. I'll have to open it again to tell you exactly which board since I only notice the "PGM" part written on it, not the full identification. Suggestions for a tech in Montreal would also be appreciated!
Considering parting away from:
-Roland TR707
-DSI Mopho

User avatar
th0mas
Expert Member
Expert Member
Posts: 1349
Joined: Thu Jul 14, 2005 5:27 pm
Gear: oakley tm3030/mopho keys/midibox sid/tr-707/tama techstars/monotron
Band: GRAVITRONIC
Location: Ontario
Contact:

Re: Yamaha CS-20M stuck in load/store mode (no sound) Ed: Fr

Post by th0mas » Wed Oct 12, 2011 10:14 pm

Just out of interest, I wonder if you can ID it to match this one:



little nick near underneath the top keys?

Not that I can help you, although I know that it was blowing fuses when I had it about 3 years ago and if I had kept it I'd have rebuilt the power supply. Did you find the schematics? I think I have a copy somewhere..

User avatar
rhino
Supporting Member!
Supporting Member!
Posts: 2610
Joined: Sat Aug 02, 2008 5:00 pm
Real name: bill
Gear: keepers:
Kurzweil K2500x
Ensoniq TS-12
Yamaha SY-99
Alesis QS-8
Roland JD-800
Roland JX-10
Akai AX-80
Ensoniq SQ-80
Korg DSS-1
Moog Mini
Fizmo
Location: kentucky hills

Re: Yamaha CS-20M stuck in load/store mode (no sound) Ed: Fr

Post by rhino » Wed Oct 12, 2011 11:33 pm

fh991586 wrote:I have no idea what tantalum caps are,
In the picture of the burned IC, they are the blue blobs - others in the synth may be orange.
When the wise man points to the stars, the fool looks at the finger.
- Confucius

User avatar
fh991586
Senior Member
Senior Member
Posts: 972
Joined: Sun Sep 26, 2010 10:20 pm
Real name: Francis
Gear: Roland JX3P, D50, U220, MVS1, JP8080.
Korg Kaossilator, Monotrons, MicroKorg, M3R.
Yamaha Motif Rack.
Midines
Location: French Canada

Re: Yamaha CS-20M stuck in load/store mode (no sound) Ed: Fr

Post by fh991586 » Thu Oct 13, 2011 1:22 am

th0mas wrote: little nick near underneath the top keys?
Mine isn't nicked, so it ain't the same unit. But they all seem to suffer the same problems after 30 years!

I don't have th schematics, and I wouldn't be able to change anything that is soldered by myself. If I can't have it fixed for under 200$, I'll try to sell it as is (or for parts). Since I was not even able to play with it first, my interest in this synth is getting lower every week. It's not like I don't have anything else to play with...

But I really wish it could be put to use again, even if in someone else's studio!
Considering parting away from:
-Roland TR707
-DSI Mopho

Post Reply