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My CS-80 is almost fully working again! (with pics)

Posted: Sat Apr 04, 2009 8:56 pm
by hfinn
I've put A LOT of work and time into the CS-80 and it's almost back up to 100%.

It sat since 1987 after it just quit one day. Here is a list of what's been done to it.

-Power supply completely rebuilt (from PSU in the 80 belonging to Toto. So there is a little bit of "Rosanna" in this CS-80)
-Output hi/lo switch rebuilt
-bad circuit trace repaired causing the pitch to be the same across the keybed
-"Funky 3" preset fixed as it did not sound
-IC replaced on voice 3 mix 2 as there was no square wave (bad IG00158 chip)
-Mix 2 PWM slider replaced
-Ring mod envelope repaired (bad IG00159 chip)
-bad trace on keyboard board causing the AT sensors not to work
-lots of 4xxx CMOS chips replaced

All that is left now is that the VCO aftertouch is not working, nor is the AT speed. From where it was this is excellent. Once this is done it will have a full calibration.

Better than it's looked in ages:

Image

Sub OSC noise:

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Sub OSC sine:

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Toto's contribution:

Image

Re: My CS-80 is almost fully working again!

Posted: Sat Apr 04, 2009 9:06 pm
by Esus
Nice to see a great success story, especially with such a beast.
Congratulations!
Sound files to come??

Re: My CS-80 is almost fully working again!

Posted: Sat Apr 04, 2009 9:09 pm
by hfinn
Esus wrote:Sound files to come??
Once I tackle that aftertouch problem and calibrate it. Its a bit out of tune from all the work as you can imagine.

Re: My CS-80 is almost fully working again! (with pics)

Posted: Sun Apr 05, 2009 1:15 am
by gd
Great work!! The CS-80 has always been one of my favourite synths, did you have much difficulty finding the parts?

Re: My CS-80 is almost fully working again!

Posted: Sun Apr 05, 2009 1:20 am
by Automatic Gainsay
hfinn wrote:
Esus wrote:Sound files to come??
Once I tackle that aftertouch problem and calibrate it. Its a bit out of tune from all the work as you can imagine.
All of that work, and you still have yet to face the worst. :wink:

Re: My CS-80 is almost fully working again! (with pics)

Posted: Sun Apr 05, 2009 2:52 am
by hfinn
Hahaha, I'm making great progress on the aftertouch. Already got it working for the filter, just need to figure out the VCO. Parts were easy to find since I had a CS-60 for parts.

Re: My CS-80 is almost fully working again! (with pics)

Posted: Sun Apr 05, 2009 3:11 am
by Esus
hfinn wrote:Hahaha, I'm making great progress on the aftertouch. Already got it working for the filter, just need to figure out the VCO. Parts were easy to find since I had a CS-60 for parts.
I'm pulling for you man...I downloaded one of your files a year or two ago, and I listen to it a lot. Mr. V would be proud... :D

Re: My CS-80 is almost fully working again! (with pics)

Posted: Sun Apr 05, 2009 7:52 am
by guitarsandsynths
Very nice! I can't wait to hear you play it.
Congrats!

Re: My CS-80 is almost fully working again! (with pics)

Posted: Sun Apr 05, 2009 8:46 am
by killertofu
:shock: How did they BUILD that thing?

When the CS80 was designed, was Yamaha taking a huge risk in order to prove themselves? Or did such a category in synthesizers simply not exist at that point making the CS80 viable?

Re: My CS-80 is almost fully working again! (with pics)

Posted: Sun Apr 05, 2009 12:41 pm
by StepLogik
What a beast! Congrats on all the success you've had so far!

Re: My CS-80 is almost fully working again! (with pics)

Posted: Sun Apr 05, 2009 1:05 pm
by HideawayStudio
hfinn wrote:I've put A LOT of work and time into the CS-80 and it's almost back up to 100%.

It sat since 1987 after it just quit one day. Here is a list of what's been done to it.

-Power supply completely rebuilt (from PSU in the 80 belonging to Toto. So there is a little bit of "Rosanna" in this CS-80)
-Output hi/lo switch rebuilt
-bad circuit trace repaired causing the pitch to be the same across the keybed
-"Funky 3" preset fixed as it did not sound
-IC replaced on voice 3 mix 2 as there was no square wave (bad IG00158 chip)
-Mix 2 PWM slider replaced
-Ring mod envelope repaired (bad IG00159 chip)
-bad trace on keyboard board causing the AT sensors not to work
-lots of 4xxx CMOS chips replaced

All that is left now is that the VCO aftertouch is not working, nor is the AT speed. From where it was this is excellent. Once this is done it will have a full calibration.

SUPERB! Another great classic lives again! Any chance of posting some of your pics in my new synth guts thread??

Re: My CS-80 is almost fully working again! (with pics)

Posted: Sun Apr 05, 2009 1:18 pm
by HideawayStudio
killertofu wrote::shock: How did they BUILD that thing?

When the CS80 was designed, was Yamaha taking a huge risk in order to prove themselves? Or did such a category in synthesizers simply not exist at that point making the CS80 viable?

Yamaha have a bit of a history of making loss leading flagships - I suspect being such a huge company they've been able to afford taking such risks over the years. The SY99 was a flagship which I doubt made Yamaha money either.

The labour costs must have been incredible in those days. These things were made by hand at enormous expense.

If you ever want to see the very pinacle of quality hand build in electronics then look no further than the Tektronix 500 series scopes from the early 60's - huge 70 tube beasts in all aluminium chassis with chrome fixings, ceramic tag board and silver soldered with truely amazing build quality - works of art and a lost era for sure!!

Re: My CS-80 is almost fully working again! (with pics)

Posted: Sun Apr 05, 2009 9:11 pm
by hfinn
Fixed the aftertouch issue. 8(!) bad IC's. Luckily I had exactly 8 spares. Now it's good enough to calibrate it and put it to use.

Re: My CS-80 is almost fully working again! (with pics)

Posted: Mon Apr 06, 2009 12:42 am
by hfinn
As promised...



Re: My CS-80 is almost fully working again! (with pics)

Posted: Mon Apr 06, 2009 1:03 am
by StepLogik
hfinn wrote:As promised...


absolutely beautiful.