Quasar WP3422QW only stays on for a couple seconds

[vol.2]

Originally Posted by blue lander

I replaced C809 and C812, made no difference. I'll try replacing the 2k potentiometer and see if turning that changes the voltage or not. I'm measuring an open circuit between the wiper and either leg on that potentiometer so it's either bad or dirty.

Before you go throwing more parts at it, you should start by checking some voltages. If you look in the schematic, you can see that voltages are called out at points around the transistors and other substantive junctions.

If you can confirm that voltages are all correct around a transistor, then you probably have a working transistor.

If the voltages aren't right, then pull the transistor and do a diode test on all of the legs to confirm it's still a transistor. If it looks good and the voltages are wrong, then you have more information about where the problem is (depending on which leg(s) of the transistor are wrong.

Then you just keep going this way until you encounter a bad part.