This amp has +6.22vDC across speaker terminals and no audio output. I have audio on the two 100uf caps near the SMD 5532 opamps in the Class-D section.
The optocouplers have the following voltages on them, which seems wrong? Still researching...
3120 Closer to board edge
1. 0
2. -0.233
3. 0
4. 0
5. 6.22 <-Same as terminal voltage
6. 5.82
7. 5.82
8. 24.28
3120 slightly inward
1. 0
2. 0
3. -0.233
4. 0
5. -70.0
6. -68.3
7. -68.3
8. -0.389
LED400 is lit. Im not sure if its supposed to be lit. Its near the Otto couplers thought I'd mention.
Would there be a set of regulators I should look into? Board looks pristine. Amp draws 2.5A when powered.
The optocouplers have the following voltages on them, which seems wrong? Still researching...
3120 Closer to board edge
1. 0
2. -0.233
3. 0
4. 0
5. 6.22 <-Same as terminal voltage
6. 5.82
7. 5.82
8. 24.28
3120 slightly inward
1. 0
2. 0
3. -0.233
4. 0
5. -70.0
6. -68.3
7. -68.3
8. -0.389
LED400 is lit. Im not sure if its supposed to be lit. Its near the Otto couplers thought I'd mention.
Would there be a set of regulators I should look into? Board looks pristine. Amp draws 2.5A when powered.
It's supposed to be lit.
Measure across pins 5 and 8 on both optocouplers. What voltage do you get?
Measure across pins 5 and 8 on both optocouplers. What voltage do you get?
Is FET 401 shorted?
Did you see the 7801 page? If so ctrl-f on the page for:
The other 3120 (the one on
Did you see the 7801 page? If so ctrl-f on the page for:
The other 3120 (the one on
FET401 is a TO220 behind the RCAs clamped. It does not appear shorted. -0.472, 0, -0.472 volts on legs referencing B-.
Ive been reading through the 7801 pages, flash enabled. I'm on the 3120 sections. Still troubleshooting.
Ive been reading through the 7801 pages, flash enabled. I'm on the 3120 sections. Still troubleshooting.
When the 20v zener gets pulled up to more than 20v, that should drive the lower transistor on which drives the upper base transistor lower which should reduce the gate voltage on the FET. That should limit the output of the regulator. With these regulators, you sometimes have to check every part in their circuit.
I also found C408 next to Q401 depleted. When I replaced C408, the amp draws excessively and C408 gets very hot. Theres ~70vDC across C408 pads. C408 is a 1000u35v cap
I've looked through some photos. The diodes vary I've seen j5 and h5. The 20v value comes from an 81000. I have some notes that indicate that I used a MMSZ5245B in one amp.
I don't think it's all that critical (neither did MTX). The optocoupler that's in there is almost certainly. It took twice its rated voltage.
Recheck that FET.
I don't think it's all that critical (neither did MTX). The optocoupler that's in there is almost certainly. It took twice its rated voltage.
Recheck that FET.