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Old 05-05-2021, 02:38 AM   #3
Join Date: May 2017
City & State: Belgrade
My Country: Serbia
Line Voltage: 230V 50Hz
I'm a: Knowledge Seeker
Posts: 37
Default Re: DTK 400W PSU Power Good signal 0V fault

Sorry, I made a mistake. The pin 13 goes directly to the PG wire.

Something at the inputs of the Op-Amp is the problem (probably leading to the pin 11), but it is very hard to trace on the board.

Pin 11 goes to the voltage divider, a 100 Ohm series resistor through a diode to the pin 14 (the output of the another comparator). But pin 11 also goes in different direction, eventually leading to the transistor.

Now I am checking the other comparator. Pin 14 is 0V, pin 8 is 1.25V and pin 9 is 0V.

Now I am tracing the pin 8 and 9. I found a cold solder joint on the 1uF 50V capacitor. Soldered it. Checked the PG, it is still 0V. Checked all the voltages again,and the blue wire (-12V) is 0V. I am not sure if I checked that voltage before or not.

Now I am checking out the -12V rail.

EDIT: I have changed the two 220zF 16V capacitor on the -12V rail and now that rail is fine it measures -11.2V. But the PG signal is still 0V.

Last edited by PanicMechanic; 05-05-2021 at 03:16 AM..
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