Hi!
High-pass and Full-range filters work. Low-pass filter makes a loud thump when engaged and then there is no sound.
It pops when I change the RCA output xover.
High-pass and Full-range filters work. Low-pass filter makes a loud thump when engaged and then there is no sound.
It pops when I change the RCA output xover.
Measure the DC voltage on the output pins of the op-amps near the RCA end of the board. Do any have more than a few millivolts of DC? If so, does the offset vary significantly when adjusting the gain?
What is the DC voltage on pins 1 and 8 of U6?
Use the RCA shield as the reference (black meter probe on RCA shield).
What is the DC voltage on pins 1 and 8 of U6?
Use the RCA shield as the reference (black meter probe on RCA shield).
The NE5532 right behind the gains has significant voltage change on the outputs when gains turned. The rest appear to have 3mV of offset.
U6
1: -.75V
2: 3.2V
3: .4mV
4: -2.6V
5: -57mV
6: -22mv
7: .4mV
8: -.75V
U6
1: -.75V
2: 3.2V
3: .4mV
4: -2.6V
5: -57mV
6: -22mv
7: .4mV
8: -.75V
Pull U6 and install a jumper from pin 1 to pin 8. Does the amp work normally (low frequency crossover working, no pop, no DC offset)?
Hello!
Yes, after removal it appears to work normally. Slight pop when engaging the switch, but nothing like it was before. Offset is now normal on the NE5532.
Yes, after removal it appears to work normally. Slight pop when engaging the switch, but nothing like it was before. Offset is now normal on the NE5532.
Replacing the THAT 2155 will probably solve the problem The 2155 is obsolete. You'll have to replace it with a 2180 (mouser - search for THAT 2180).
The amp will work without it but the remote level controller and the compressor (if it has one) won't work.
The amp will work without it but the remote level controller and the compressor (if it has one) won't work.
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