Yep. I suggest that you add more context and, if possible, a schematic of this circuit. Where did it come from? What's it do?
Tom
Tom
Are you sure that you're grounding the base of Q5 to get the relay to engage?
The base of Q5 has to go high for the relay to engage. I think it's Q4 that pulls it high.
If there is a really high value resistor near Q3 at the top of the board, check it. It will likely have to be removed to confirm it's within tolerance.
The base of Q5 has to go high for the relay to engage. I think it's Q4 that pulls it high.
If there is a really high value resistor near Q3 at the top of the board, check it. It will likely have to be removed to confirm it's within tolerance.
Sorry when I ground the center leg,
Q5
1: 0.001
2 :12.68
3 :0.003
Q6
1: 2.637
2: 5.00
3: 2.115
Q4
1: 0.004
2: 12.66
3: 0.013
Q3
1: 0.533
2: 0.007
3: 0.001
Q5
1: 0.001
2 :12.68
3 :0.003
Q6
1: 2.637
2: 5.00
3: 2.115
Q4
1: 0.004
2: 12.66
3: 0.013
Q3
1: 0.533
2: 0.007
3: 0.001
Did you check the resistor?
Is Q4 shorted or leaking from base to emitter?
Looking at Q3, it appears that it's being driven on. What is the DC voltage on pins 1 and 2 of the driver IC?
Is Q4 shorted or leaking from base to emitter?
Looking at Q3, it appears that it's being driven on. What is the DC voltage on pins 1 and 2 of the driver IC?
Remove R7, next to Q3. Does the amp work normally?
DCV on pin 3 of the driver IC with and without R7?
DCV on pin 3 of the driver IC with and without R7?