I followed the troubleshooting guide offered by QSC Service Manual starting pg 31 to test PSU/AMP board isolated. The line filter components test shown at the top of the page tested good.
Previously I found Q13 & Q14 suspect and replaced them.
I have checked the voltages shown on the bottom of pg 31 chart of the linked service manual and found only .6-.9 volts where there should be 41vdc between VIN and PRI_LO, measured at R147 to R150. I measured on both sides of the resistors in case they were bad.
The trace is good between the 2 resistors and the 41volts originates at U15 pin 16 I think. Schematic for that is on pg 36. Difficult to check an IC but found no shorts between it's pins.
Can anyone suggest why this might be, or what to check next?
Thanks!
Here's the link to the service manual:
https://elektrotanya.com/qsc_k-serie.../download.html
Previously I found Q13 & Q14 suspect and replaced them.
I have checked the voltages shown on the bottom of pg 31 chart of the linked service manual and found only .6-.9 volts where there should be 41vdc between VIN and PRI_LO, measured at R147 to R150. I measured on both sides of the resistors in case they were bad.
The trace is good between the 2 resistors and the 41volts originates at U15 pin 16 I think. Schematic for that is on pg 36. Difficult to check an IC but found no shorts between it's pins.
Can anyone suggest why this might be, or what to check next?
Thanks!
Here's the link to the service manual:
https://elektrotanya.com/qsc_k-serie.../download.html
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