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Old 10-05-2020, 04:27 PM   #25
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Default Re: troubleshooting definitive technology prosub 60

Originally Posted by momaka View Post
We can try to figure out what they should be as well... but I'm not sure what you mean by those "P1", "P2", and "P3" test points. It would be easier if you use the component pin designators - i.e. Gate, Drain, Source.
Hey momaka...Sorry I was referring to the pins for that mosfet. 1 is gate, 2 is drain, and 3 is source.

Originally Posted by momaka View Post
However, looks like Q4 is running hot, while Q2, Q3, and Q5 aren't (?)
In that case, I suggest you remove Q4 and test it out of circuit. Better yet, replace it if you have spares.
Also check the values of all resistors that connect to Q4. I don't believe Q4 should be running hot at all with the main transistors (Q1 and Q7) removed.

While at it, also check the voltages across C21 and C27, then report back what they are.
And if you can, check voltages across C5 and C6 as well (but be careful around these, since they are on the primary side.)
It only appears that Q4 is warm. I will test as I don't have any spares. I tested R12 and it was fine. I will have to figure out where R5 is. Most of the resistors are soldered right next to the board and I can read the screen printing underneath them but I can figure it out.

I will also check C21 and C27 and C5 and C6. Thanks so much for your help.
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