Re: Dead CS80 - finding a short
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Great news!
FYI, when I had similar problems with TSB cap shorts, it was confusing because it didn’t show up as a short to ground.? Instead, the short was between +15 and and -15.? Something about the load on the +15 causing too much current - and blowing the fuse - on the -15. I don’t remember the details - I think I posted about it.? Took some time to figure out.
?David
I am happy to announce that my CS80 is fine and working great again.I would like to post a resumé for anybody who will have that problem in the future.
1. My CS80's power supply died after i made adjustments on BA, KAS, S&H and M boards for tuning. First it was the problem that 4 presets were not working on the M board 4 channel 1. Note: KAS, S&H, TKC and both TSB boards had all their CMOS changed and. TSB1 was fully recapped and TSB2 partially. No fuses were blown. 2. I don't really know what caused the problem. I was paying attention not to do any shorts. It could have been altering the voltages on the KAS board, the PSU has never been rebuild, and i had few tantalum capacitors left on TWS and TSB2 boards. 3. After replacing all the tantalums and rebuilding the PSU the CS80 was working with no issues. 4. I was thinking, that I have a short between the GND ans +15 rails (I had 1s beep on my DWM). Apparently that was not the issue (the short beep could be the caps charging).
Thank you all for your help. I would like especially thank Martin who has been a wonderful help and while he's not an synth technician himself he shared all his knowledge and experience with me walking me through several procedures to test my CS80 responding patiently on my emails.
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Re: Dead CS80 - finding a short
Great news!
FYI, when I had similar problems with TSB cap shorts, it was confusing because it didn’t show up as a short to ground. ?Instead, the short was between +15 and and -15. ?Something about the load on the +15 causing too much current - and blowing the fuse - on the -15. I don’t remember the details - I think I posted about it. ?Took some time to figure out.
?David
toggle quoted message
Show quoted text
I am happy to announce that my CS80 is fine and working great again.I would like to post a resumé for anybody who will have that problem in the future.
1. My CS80's power supply died after i made adjustments on BA, KAS, S&H and M boards for tuning. First it was the problem that 4 presets were not working on the M board 4 channel 1. Note: KAS, S&H, TKC and both TSB boards had all their CMOS changed and. TSB1 was fully recapped and TSB2 partially. No fuses were blown. 2. I don't really know what caused the problem. I was paying attention not to do any shorts. It could have been altering the voltages on the KAS board, the PSU has never been rebuild, and i had few tantalum capacitors left on TWS and TSB2 boards. 3. After replacing all the tantalums and rebuilding the PSU the CS80 was working with no issues. 4. I was thinking, that I have a short between the GND ans +15 rails (I had 1s beep on my DWM). Apparently that was not the issue (the short beep could be the caps charging).
Thank you all for your help. I would like especially thank Martin who has been a wonderful help and while he's not an synth technician himself he shared all his knowledge and experience with me walking me through several procedures to test my CS80 responding patiently on my emails.
|
Re: Dead CS80 - finding a short
I am happy to announce that my CS80 is fine and working great again. I would like to post a resumé for anybody who will have that problem in the future.
1. My CS80's power supply died after i made adjustments on BA, KAS, S&H and M boards for tuning. First it was the problem that 4 presets were not working on the M board 4 channel 1. Note: KAS, S&H, TKC and both TSB boards had all their CMOS changed and. TSB1 was fully recapped and TSB2 partially. No fuses were blown. 2. I don't really know what caused the problem. I was paying attention not to do any shorts. It could have been altering the voltages on the KAS board, the PSU has never been rebuild, and i had few tantalum capacitors left on TWS and TSB2 boards. 3. After replacing all the tantalums and rebuilding the PSU the CS80 was working with no issues. 4. I was thinking, that I have a short between the GND ans +15 rails (I had 1s beep on my DWM). Apparently that was not the issue (the short beep could be the caps charging).
Thank you all for your help. I would like especially thank Martin who has been a wonderful help and while he's not an synth technician himself he shared all his knowledge and experience with me walking me through several procedures to test my CS80 responding patiently on my emails.
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Re: Dead CS80 - finding a short
No short after all?? I have just read that the short beep on the dvm can be capacitors charging! And the overall resistance should be 0,00 Ohm for a short.
I have changed the two biggest caps and the two big transistors on the psu. One of the caps had a bump on the top. So it could have been a psu problem after all. It is now fully rebuilt and calibrated. All the voltages are present.
Still I am afraid to connect my synth to it and test.? Is there a way to test the psu itself under load without a specialist equipment?
Please advice.
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Re: Dead CS80 - finding a short
I have replaced all the remaining tantalums on the TWS and TSB boards. I have checked them all for short - there appears to be none. My synth still shows the following values between the +15 and G:
- Diode (continuity): 0,70 ,Short beep - On the 20k Ohm setting: 0,07
I might be wrong but there still seems to be a short somewhere.? I have checked several boards with my bench PSU - I have only one output. The TSB boards for example draw 0,060A on 15V setting with no signs of overheating any IC.
My PSU is working and calibrated but I am afraid to do another test of the synth because - i repeat - there are no fuses that were blown only PSU fried while the synth was making a brief low tone.
I am out of ideas but I have a feeling that it can be something simple. One more thing: With no molex connected to the psu the ground from all the cards show continuity with the ground on the PSU ( the green cable) is that normal?
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Re: Dead CS80 - finding a short
Ok guys, I will rebuild the TWS, TSB and I will report how it went. Seems scary however that one capacitor or ic can cause so much trouble.
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Re: Dead CS80 - finding a short
Yep - I had this issue with a CS80 a few years ago and eventually traced it to shorts in caps on the TSBs. Definitely should replace all the tantalums on both. The easy way is the kit offered on eBay if you don't want to figure out what kinds of caps to buy.?
? David
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On Feb 18, 2017, at 12:10 PM, Tommy Salsero tommysalsero@... [yamahacs80] < yamahacs80@...> wrote:
Because in my old cs80 ?the tantalum in tsb cause the short of the rail. changed the tantalum ?solved my problems,?
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Re: Dead CS80 - finding a short
Because in my old cs80 ?the tantalum in tsb cause the short of the rail. changed the tantalum ?solved my problems,?
Thanks Tommy, Tsb 1 and 2 were partially rebuilt (there are some old tantalums on tsb2 left I think) with all the IC?s changed. I have never touched the TWS.?
Why do you think that might be the problem??
The thing is that no fuse blows. The short simply kills my PSU directly.
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Re: Dead CS80 - finding a short
Thanks Tommy, Tsb 1 and 2 were partially rebuilt (there are some old tantalums on tsb2 left I think) with all the IC?s changed. I have never touched the TWS.?
Why do you think that might be the problem??
The thing is that no fuse blows. The short simply kills my PSU directly.
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Re: Dead CS80 - finding a short
Change all the tantalum condenser from TSB 1 & 2 and TWS.?
I am really confused now... Since the upper and lower rails are shorted I?ve figured that if I disconnect the bottom (+15v) rail from the three brown cables and then take the cards out one by one I could identify which one causes the short easily. The short has stopped only when I take all of them (naturally). But if I bring a single one back it causes a small short (0,1ohm or 098 on diode continuity check with a short beep). So it?s supposed to be like that or are all of them bad?
Thanks in advance for any help
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Re: CS-80 for sale in Chicago
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? I've got a CS-80 for sale in Chicago.? it includes a flight case and pedal.? I plan on going through it in the next week or so.? Asking 15K.
-Mike Borish
312-363-7286
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CS-80 for sale in Chicago
I've got a CS-80 for sale in Chicago.? it includes a flight case and pedal.? I plan on going through it in the next week or so.? Asking 15K. -Mike Borish 312-363-7286
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Re: Dead CS80 - finding a short
I am really confused now... Since the upper and lower rails are shorted I?ve figured that if I disconnect the bottom (+15v) rail from the three brown cables and then take the cards out one by one I could identify which one causes the short easily. The short has stopped only when I take all of them (naturally). But if I bring a single one back it causes a small short (0,1ohm or 098 on diode continuity check with a short beep). So it?s supposed to be like that or are all of them bad?
Thanks in advance for any help
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Re: Dead CS80 - finding a short
So can someone confirm how to find a short of +15v and a ground rail?
1. Disconnect the board from the rails 2. Unsolder E, +15v terminals (should I disconnect -15v too?) 3. Perform a simple continuity test between disconnected +15 and E terminals on the board (is that enough?)
From the information Martin gave me a simple continuity check is not enough. So I should:
4. Hook up the +15V (-15V also?) terminal to the external PSU (can it be something simple or should I get a variable bench psu?) 5. What should be measured now?
PS. I have tried to perform a simple continuity check on some boards and I get some readings - A tiny short beep and something like 1452 reading. Is that within the tolerance or is the board bad?
Lots of questions - sorry guys but it has been a long night.
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Re: Tuning..again - Transposition gate zeroing?
Hi Michael, Thank you very much for contacting me. I know your blog very well - it has been a great guide and a source of very valuable information to me. I have learned a lot reading it preventing me to make several mistakes. What has happened to my synth is very unfortunate and I am also very frustrated. Right now I have upper and lower rails shorted and I am trying ro find a cause. I have created a separate thread to address this issue. Thanks again.
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Re: Tuning..again - Transposition gate zeroing?
Hello Pyjamagroove,
I see you are trying to calibrate your CS80. A year ago I did a complete calibration of my CS80 from scratch and I am happy that I didn't commit suicide during it, also Joachim and a good friend have been a big help through my journey too. I also killed some parts here and there, unfortunately also a custom chip, but I was able to sacrifice one from the chorus which I don't use. I see that you are puzzled here and there, so was I for days. :)
I documented the whole challenge and findings and workarounds in a blog (so if I have to ever do it again I know where to get my own information that I already forgot :)). I also updated the calibration documentation.
Maybe it's some help here and there to you when you stumble over all the wonderings. Check it out:
kind regards, Michael
---In yamahacs80@..., <pyjamagroove@...> wrote : Thanks Joachim. I have managed to make the adjustments on the KAS a little better (still few cents out tough..) Now I have finished the complete tuning procedure and it seems to be pretty neat. I have found out that after completing the step 8 it is important do repeat the 7 and 8 again until it?s within the specs. After finishing the procedure a strange problem manifested itself...the board 4 channel 1 is mute ?at the panel, memory 1,2 and funky 3 buttons (it is like there is no trigger). Other presets work fine on it but it seems to be louder that the others..
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Re: Dead CS80 - finding a short
Hello, No, I did not change them or even think that they can be an issue because the PSU was working after recap and changing two 1ohm white ceramic resistors next to the heatsink (they were both interrupted) After it failed again in the same way everything seemed intact and the resistors were ok so i changed only the two IC?s and it worked again.
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Re: Dead CS80 - finding a short
Was unsuccessful linking a picture, will send to you directly.
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pyjamagroove