[sdiy] can a PSU destroy voices chips?

Paul Schreiber synth1 at airmail.net
Mon Nov 18 17:33:20 CET 2013


Yes, this is normal.

Paul S>


--- antoniotuzzi at gmail.com wrote:

From: Antonio Tuzzi <antoniotuzzi at gmail.com>
To: Synth DIY <synth-diy at dropmix.xs4all.nl>
Subject: [sdiy] can a PSU destroy voices chips?
Date: Mon, 18 Nov 2013 17:24:39 +0100

Hello friends

after more than 3 years I decided to repair the ProOne... 

was working, but one day decided to stay mute

situation was this:

-15v ok
- 5 ok
+ 5 -> 4.3
+15 -> at startup was around 12 going down to zero in 5 seconds


after changing the regulators (no success)
changed all the caps in the regulators area and more (and the 2 bigs)
I tested the PSU with no load (it's a an DP 241 5 36, dual V 220 and 110)  (only 0.35 A, seems very LOW!!!)
and on the secondary I had 20,7 and 20,7 

but I decided to test with another PSU, at this point, the positive regulators were giving correct Voltages +5 and +15

but all the cem3340 were silent, no sign of oscillations on the oscilloscope

All DEAD! 

This is the first time I've seen so many 3340 dead at the same time :((((

I had 3 new 3340 and the pro one is working ( I discovered a DEAD 3310 too... filter ADSR)

Question
Is it (A)normal that a bunch a CEM are dead for a failing positive rails ?


Thanks
Antonio
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