Re: 2235 AN/USM-488 power supply low voltages


 

On Fri, Mar 5, 2021 at 04:31 PM, Raymond Domp Frank wrote:


You may consider noting as exactly as you can the current -7.3V of the -8.6V
supply to be able to see if the voltage changes by slightly adjusting R938 and
carefully readjusting it to the current voltage afterward.

By temporarily re-adjusting R938 you'll likely be able to see if the drive level of the inverter is hard enough. All voltages being off by approximately the same percentage indicates there may be a drive problem, not a load problem.
If the 8.6V can be adjusted up and down, there's probably a reference- or compare-problem (R937/938/939, VR943 and possibly R943, which may have badly drifted).

Raymond

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