Yamaha CS-80 Technical Question

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Jonathan G
Posts: 25
Joined: Sat Mar 19, 2011 11:54 pm

Yamaha CS-80 Technical Question

Post by Jonathan G » Wed Jan 24, 2018 12:46 pm

With the power off, I am getting a 70-ohm resistance between the +15V power rail on the card riser (the lower bar that the cards screw into) and ground. Does anyone know if this is normal or is this indicative of a partial short?

zaiusz
Posts: 47
Joined: Mon Mar 05, 2012 10:58 pm
Location: Torontoish

Re: Yamaha CS-80 Technical Question

Post by zaiusz » Wed Jan 24, 2018 10:51 pm

I'm assuming you're testing this since it doesn't turn on? did you lose the 15v rail ?

Jonathan G
Posts: 25
Joined: Sat Mar 19, 2011 11:54 pm

Re: Yamaha CS-80 Technical Question

Post by Jonathan G » Thu Jan 25, 2018 11:43 pm

I did some minor work inside the keyboard, and when I turned it back on it blew a 500mA fuse and the synth went dead, and want to make sure there are no shorts before powering it back up. As far as I know, the 15V rail will get power when I turn it back on.

Jonathan G
Posts: 25
Joined: Sat Mar 19, 2011 11:54 pm

Re: Yamaha CS-80 Technical Question

Post by Jonathan G » Fri Feb 09, 2018 12:36 pm

Here are the resistances I'm getting between the power rails and ground:
+15V = 70.3 Ohms
-15V = 64.5 Ohms
+8.5V = 337 Ohms
-6.5V = 878 Ohms
+10.6V = 540 Ohms
The rails can be accessed on the power supply just behind the output molex connector. The +15V is the brown wire at the top and they go down from there. I'm thinking my -6.5V could be low as a friend is getting 3.95 Kohms on his currently working unit, as well as 456 Ohms on the +8.5. If anyone can take similar measurements so we can compare and determine a standard, it'd be greatly appreciated.
Cheers,
Jonathan

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