PSU Studer 169 oscillation
« on: October 11, 2018, 07:33:47 AM »
Here is a Studer power supply.
There is a background whistle on all console buses, tuned to 6.8 kHz.
I have tested with the laboratory PSU and the sound is clean.
The problem seems to come from the PSU, but I do not find the oscillation.
I have replaced all the condesadores, the two integrated circuits and checked the rest of the components.
Any suggestions?

https://ibb.co/gO7UuU


Re: PSU Studer 169 oscillation
« Reply #1 on: October 11, 2018, 03:52:40 PM »
I just checked, with the original power supply , in addition to tone also a lot of background noise.
I have also checked with this:
https://szpcsy.en.made-in-china.com/product/qytmkTJxTlcA/China-48V-0-25A-15V2-5A-15V2-5A-triple-output-switching-power-supply-for-audio-equipment.html
With the Chinese psu, the sound is clean
 :P

mjrippe

Re: PSU Studer 169 oscillation
« Reply #2 on: October 12, 2018, 02:23:00 PM »
Any suggestions?

Yes, get rid of the Studer supply and use the one from China  ;D  Seriously though, the last 169 I worked on it was easier and less expensive to replace the PSU.

Re: PSU Studer 169 oscillation
« Reply #3 on: October 12, 2018, 05:34:41 PM »
Yes, get rid of the Studer supply and use the one from China  ;D  Seriously though, the last 169 I worked on it was easier and less expensive to replace the PSU.

PSU replaced by another? What brand and model?

moamps

Re: PSU Studer 169 oscillation
« Reply #4 on: October 14, 2018, 06:02:43 AM »
The problem seems to come from the PSU, but I do not find the oscillation.

How did you test it, under the load or without?
Do you have a scope?
BTW, where did you bought the Chinese PSU?

Re: PSU Studer 169 oscillation
« Reply #5 on: October 17, 2018, 03:33:16 AM »
Everything has been solved. I have redone the power source. Two 7815 have been my salvation. The perfect voltage, there is no oscillation and the background noise has been reduced considerably.


 

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