Hi Gavin, i made the adjustment procedure and concluded i needed to change some parts on the PSU side.I'm interested by your PSU rebuild kit.Found it on your ebay and sent you a question about the content of the package (if it include all PSU parts with no exception, or only some selected parts.Waiting dor your answer before purchasing, thank you!
Thanks. What transformer are you looking for? I recall you had a video where you were looking for a vibrato transformer. I would rewind it. Do you have any info regarding turn ratio etc?
I commend you.. perhaps you could help me (or lead me) in the right direction for the right replacement transformer for my Hammond T-212... that is.. REPAIR the board rather than replace it... I like how you resolder ALL connections... always nags at the back of your mind wondering if shock might have ruptured a weld..... 5 stars bro....
Hey man, I just fixed one CS80 which had a power supply problem caused by somebody doing just what you describe. They replaced perfectly good original capacitors with new Panasonic but the ESR of the cap is too low and caused instability. I can see you haven't checked the output of the PSU with an oscilloscope to ensure the voltages you measure are stable and free of any ripple. I fixed the problem by putting back the old perfectly good Nippon Chemicon caps and it's now clean as a whistle. Another issue I see is during the calibration procedure this needs to be measured between the tie points in the middle of the rails holding the cards, not on the PSU itself. Currents aren't insignificant here so there is voltage drop between PSU and the rails.
Interesting! I never had any ripple or issues on my CS80's I had rebuilt with this particular kit. Knock on wood... was this from one the PSU kits you had issue? I have not encountered a problem as of yet with ESR of the new capacitors provided in the kit. I tried to keep with Panasonic EB, which have higher ESR (1-2 ohms) in trade for their 10,000+ hour lifespans. I didn't want too low of ESR to stress the rectifiers or pop the AC inlet fuse. I do use Panasonic FM series for low ESR applications aside from main filter. They are usually 0.1-0.5 ohm ESR 1kHz on my test rig. The final voltage calibration at the card rails as you suggested is ideal. The CS-80 PSU does compensate for voltage drop automatically via remote sensing, potentially allowing one location calibration of voltage at the PSU. The CS-80 PSU uses a "Kelvin Clip" type servo feedback to compensate for voltage drop across power lines from it to the card rail automatically and in real time. Many of the older Japanese capacitors were amazingly .1-.2 ohms ESR (rivaling Panasonic FM series today) in my CS-80's when tested, but were leaking electrolyte so had to be replaced. Almost every electrolytic had green lead disease in my machines.
@@gavincurtis I'm unfortunately not the only one, Steve Jones was less lucky because in his case the regulator feedback loop went into full oscillation and it killed some of the parts further up the chain (not what you want to happen to CS80) Kent Spong also said he has seen that problem before. It is critical to use higher ESR capacitors and check it before it's installed. photos.app.goo.gl/6QbXu8x2rTV4iGi1A I'm not sure if the link will work but it's how the +15V rail looked like before I swapped the capacitors back.
Hi Gavin:) I've been watching at all your maintenance videos about YAMAHA CS80, which are great! It helps me get confident about fully restoring mine without hiring a tech, but before doing any modification, i would start with those voltage measurements as described in Yamaha's adjustment procedure.But in this video regarding PSU, i would like to know if i can make those measurements directly from the connections (the ones we see at 5:30), without even going thru the 1st part of this video (w/o taking off molex connectors, adding jumpers in place)? Any damaging risks doing so? Thank you!
Hi and thanks for the compliment. You can definitely check your voltages without the jumpers. You just have to make sure the molex connectors are plugged together to the rest of the keyboard. If you power up the power supply with the molex disconnected and without the jumpers, you may damage the power supply.
Gavin Curtis Thank you for this clear explanation.I followed those advices and checked all the voltages according to Yamaha procedure.Though, it seems the's some confusion in the Yamaha procedure: in PSU adjustement page 1, they mention measurements to be made between ground and other boards (KBC for +8,5v and - 6,5v/M18 for -15v/BA for 10,6v), while on the next page the layout shows that everything should be measured on the SAME SVU board.Maybe you solved this confusion from the manual? Or are those measurements points the same in the end? For now i did measurements from SVU board exclusively, and everything is fine at measured points.By curiosity i also checked the +15S/-15S, which are more around 14,87v.Do you consider it is acceptable, or am i elegible for some PSU parts replacements? Thank you again for your help, and a big thumb up for your tech skills !
Hey Gavin, thank you for these invaluable videos. May I ask why you chose to change the uF rating of the two large caps from the original value 5600 uF to 8200 uF? Does this make the circuit superior to the original design?
Hi, going to 8200 is not necessary. I went larger because the 8200uF Panasonics had the best pin spacing and having a little extra bulk filtering headroom is not a bad thing. No issues with inrush current etc with the larger units. They also can be of benefit as the dozens of 100uF decoupling capacitors on the voice, output effects and preamp boards are end of life and leaking electrolyte on most cs80s. At least all the CS80 units I have worked on. So the extra uF helps in this case.
Oh ok, I think I will go with the higher uF rating. Thanks for the quick reply, and again for all these videos as I begin my journey restoring this wonderful machine.
could one of these synths be built from scratch today (an exact clone of the specs) with todays electronic parts...capacitors, diodes, transistors, etc. or would it sound totally different?
jeez - with those jumpers you have set up there - you're not insulating between them?? seems like you could (would) easily short out the plus and minus 15v lines with each other?
Yup, pretty bad of them to not have easy access test points. But there is no option and yes I was quite nervous. The rubber insulators force the alligator clip open when slid back far enough to make contact, so I had to take them off completely. You have to perform that test with the connector together or damage the power supply and main boards in the keyboard.
I fear this is the only hope for my struggling cp30. The hissing sound is almost as loud as the actual piano sound and there is a constant crackling. Does this sound like a capacitor issue or power transformer issue?
I like the vacuum desoldering setup :-) They save time, and you don't end up burning the boards up like people do with desoldering braid.
Hitting them with contact cleaner,and working them back and fourth would be a good idea.
BUT they would require resetting afterwards.
Hi Gavin, i made the adjustment procedure and concluded i needed to change some parts on the PSU side.I'm interested by your PSU rebuild kit.Found it on your ebay and sent you a question about the content of the package (if it include all PSU parts with no exception, or only some selected parts.Waiting dor your answer before purchasing, thank you!
Hi will you be restoring for other cs80 owners
I own one it works great but
I would like to keep her healthy and do these restorations
Thanks.
What transformer are you looking for? I recall you had a video where you were looking for a vibrato transformer.
I would rewind it.
Do you have any info regarding turn ratio etc?
I commend you.. perhaps you could help me (or lead me) in the right direction for the right replacement transformer for my Hammond T-212... that is.. REPAIR the board rather than replace it...
I like how you resolder ALL connections... always nags at the back of your mind wondering if shock might have ruptured a weld.....
5 stars bro....
Wouldn't one want to replace the trimmers? Or are the old ones decent? They do look better than some of the other ones.
Hey man, I just fixed one CS80 which had a power supply problem caused by somebody doing just what you describe. They replaced perfectly good original capacitors with new Panasonic but the ESR of the cap is too low and caused instability. I can see you haven't checked the output of the PSU with an oscilloscope to ensure the voltages you measure are stable and free of any ripple. I fixed the problem by putting back the old perfectly good Nippon Chemicon caps and it's now clean as a whistle. Another issue I see is during the calibration procedure this needs to be measured between the tie points in the middle of the rails holding the cards, not on the PSU itself. Currents aren't insignificant here so there is voltage drop between PSU and the rails.
Interesting! I never had any ripple or issues on my CS80's I had rebuilt with this particular kit. Knock on wood... was this from one the PSU kits you had issue?
I have not encountered a problem as of yet with ESR of the new capacitors provided in the kit. I tried to keep with Panasonic EB, which have higher ESR (1-2 ohms) in trade for their 10,000+ hour lifespans. I didn't want too low of ESR to stress the rectifiers or pop the AC inlet fuse.
I do use Panasonic FM series for low ESR applications aside from main filter. They are usually 0.1-0.5 ohm ESR 1kHz on my test rig.
The final voltage calibration at the card rails as you suggested is ideal. The CS-80 PSU does compensate for voltage drop automatically via remote sensing, potentially allowing one location calibration of voltage at the PSU.
The CS-80 PSU uses a "Kelvin Clip" type servo feedback to compensate for voltage drop across power lines from it to the card rail automatically and in real time.
Many of the older Japanese capacitors were amazingly .1-.2 ohms ESR (rivaling Panasonic FM series today) in my CS-80's when tested, but were leaking electrolyte so had to be replaced. Almost every electrolytic had green lead disease in my machines.
@@gavincurtis I'm unfortunately not the only one, Steve Jones was less lucky because in his case the regulator feedback loop went into full oscillation and it killed some of the parts further up the chain (not what you want to happen to CS80) Kent Spong also said he has seen that problem before. It is critical to use higher ESR capacitors and check it before it's installed.
photos.app.goo.gl/6QbXu8x2rTV4iGi1A
I'm not sure if the link will work but it's how the +15V rail looked like before I swapped the capacitors back.
Hi Gavin:) I've been watching at all your maintenance videos about YAMAHA CS80, which are great! It helps me get confident about fully restoring mine without hiring a tech, but before doing any modification, i would start with those voltage measurements as described in Yamaha's adjustment procedure.But in this video regarding PSU, i would like to know if i can make those measurements directly from the connections (the ones we see at 5:30), without even going thru the 1st part of this video (w/o taking off molex connectors, adding jumpers in place)? Any damaging risks doing so? Thank you!
Hi and thanks for the compliment.
You can definitely check your voltages without the jumpers. You just have to make sure the molex connectors are plugged together to the rest of the keyboard. If you power up the power supply with the molex disconnected and without the jumpers, you may damage the power supply.
Gavin Curtis Thank you for this clear explanation.I followed those advices and checked all the voltages according to Yamaha procedure.Though, it seems the's some confusion in the Yamaha procedure: in PSU adjustement page 1, they mention measurements to be made between ground and other boards (KBC for +8,5v and - 6,5v/M18 for -15v/BA for 10,6v), while on the next page the layout shows that everything should be measured on the SAME SVU board.Maybe you solved this confusion from the manual? Or are those measurements points the same in the end? For now i did measurements from SVU board exclusively, and everything is fine at measured points.By curiosity i also checked the +15S/-15S, which are more around 14,87v.Do you consider it is acceptable, or am i elegible for some PSU parts replacements?
Thank you again for your help, and a big thumb up for your tech skills !
Hey Gavin, thank you for these invaluable videos. May I ask why you chose to change the uF rating of the two large caps from the original value 5600 uF to 8200 uF? Does this make the circuit superior to the original design?
Hi, going to 8200 is not necessary. I went larger because the 8200uF Panasonics had the best pin spacing and having a little extra bulk filtering headroom is not a bad thing. No issues with inrush current etc with the larger units. They also can be of benefit as the dozens of 100uF decoupling capacitors on the voice, output effects and preamp boards are end of life and leaking electrolyte on most cs80s. At least all the CS80 units I have worked on. So the extra uF helps in this case.
Oh ok, I think I will go with the higher uF rating. Thanks for the quick reply, and again for all these videos as I begin my journey restoring this wonderful machine.
could one of these synths be built from scratch today (an exact clone of the specs) with todays electronic parts...capacitors, diodes, transistors, etc. or would it sound totally different?
jeez - with those jumpers you have set up there - you're not insulating between them?? seems like you could (would) easily short out the plus and minus 15v lines with each other?
Yup, pretty bad of them to not have easy access test points. But there is no option and yes I was quite nervous. The rubber insulators force the alligator clip open when slid back far enough to make contact, so I had to take them off completely. You have to perform that test with the connector together or damage the power supply and main boards in the keyboard.
I fear this is the only hope for my struggling cp30. The hissing sound is almost as loud as the actual piano sound and there is a constant crackling. Does this sound like a capacitor issue or power transformer issue?