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Need help with SMPS voltage output high

Edib

Mar 19, 2023
3
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Mar 19, 2023
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3
SMPS Schematic
https://www.allen-heath.com/media/xone_db4_db2_004_066_psu_2.pdf

Hello there
I have a music mixer failing components downstream from the PSU. After some investigation, I realized the voltage output from the PSU is higher than specified on the board or schematic.

Output should be +/-12 however reading 19v or higher. I attached a 10ohm 3w resistor to pins 9 and 3 on CN1 (see schematic) and the 12v rail jumped to 26 v.

What may be going on here?
 

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kellys_eye

Jun 25, 2010
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Pins 9 and 10 form a separate ground from the other supplies.
 

Edib

Mar 19, 2023
3
Joined
Mar 19, 2023
Messages
3
I see your point.
When I measure pin 1 against 9 (proper ground), I still see a much higher voltage output than the specified +/-12V.

When not loaded, the PSU outputs +/-15V. When I load the 5V supply rail, the 12V output more than doubles?

Is this normal?
 
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