Hi perry with r31 lifted and the red and black probes on the + and - speaker terminals I have 8.30v on them.
I stuck a used tl072c in U4 for testing and here is what I get now.
1, .015
2, .092
3, .094
4, 9.57
5, .639
6, .631
7, .632
8, 9.82
1, .015
2, .092
3, .094
4, 9.57
5, .639
6, .631
7, .632
8, 9.82
If you flip the 0/180 switch to the other position, does the voltage on 5, 6 and 7 drop to very near 0v? The voltages look OK but I'm curious about the 0.v of offset.
If you only have 8v on the speaker terminals, recheck the voltage on U17. Re-post the voltages if they've changed significantly.
What is the DC voltage on pin 7 of U11?
If you only have 8v on the speaker terminals, recheck the voltage on U17. Re-post the voltages if they've changed significantly.
What is the DC voltage on pin 7 of U11?
U17
1: 0
2: 8.31
3: 0
4: -9.56
5: 0
6: 8.36
7: 9.81
8: 0
I switched the 0/180 and still .630 and the DC volt on pin 7 of the U11 is 8.24 the r31 is still lifted.
1: 0
2: 8.31
3: 0
4: -9.56
5: 0
6: 8.36
7: 9.81
8: 0
I switched the 0/180 and still .630 and the DC volt on pin 7 of the U11 is 8.24 the r31 is still lifted.
This IC also appears to be defective. With the inverting input well above the non-inverting input, the output should be near the negative supply, not the positive supply.
I thought it was defective also.
I didnt think the TL072C readings looked right either.
Thats why I suggested you order both parts and replace them.
I didnt think the TL072C readings looked right either.
Thats why I suggested you order both parts and replace them.
Thanks Sean and Perry for your help I got the parts today and now the amp powers up fine but resistor r44 gets hot and the output is all static. here is the voltage for the U17
1: 0
2: when i touch the positive probe the amp starts to squeal.
3:.007
4: -962
5: 0
6: 8.38
7: 9.38
8: 0
1: 0
2: when i touch the positive probe the amp starts to squeal.
3:.007
4: -962
5: 0
6: 8.38
7: 9.38
8: 0
In the previous post where you listed the voltages on U17. The voltage on pin 4 wasn't right. It should have been near -10v. Re-check the voltage on that pin.
Also, with 8v+ on pin 6, I'd expect to see significant voltage on the speaker terminals unless the amp was in protect mode. Was the amp in protect mode?
Also, with 8v+ on pin 6, I'd expect to see significant voltage on the speaker terminals unless the amp was in protect mode. Was the amp in protect mode?
OK the voltage on pin 4 of the u17 is -9.62 the amps protect light comes on when the remote is first hooked up but it goes off in like 2 sec. the voltage on the speaker terminals is -1.476 I don't think the amp is in protect mode.
You could have a bad opto-coupler or a bad driver.
The driver: MIC4420CT
The coupler: HPCL 2211
Sometimes when DC is out of wack in an amp it can blow other components in the circuit.
Do you have a scope?
I didnt see R44 in the schematic??
Can you post a pic?
The driver: MIC4420CT
The coupler: HPCL 2211
Sometimes when DC is out of wack in an amp it can blow other components in the circuit.
Do you have a scope?
I didnt see R44 in the schematic??
Can you post a pic?
Hi Sean I don't know how to post a picture and no I don't have a scope. Is there anything I can test with my meter?
Take a pic and download it to your computer.
Post, then scroll down to manage attatchments and click on it.
A box will open, then click browse.
Find the picture in your computer and double click it.
Then click upload.
Once the picture is uploaded you will see it under the manage attatchments link.
The submit reply.
Post, then scroll down to manage attatchments and click on it.
A box will open, then click browse.
Find the picture in your computer and double click it.
Then click upload.
Once the picture is uploaded you will see it under the manage attatchments link.
The submit reply.
OK Sean here is the voltage's
u5 U15 U6
1: 0 1: 0 1: -9.59
2: 8.33 2: -4.04 2: -9.59
3: 8.26 3: -3.41 3: 9.84
4: -9.61 4: 0 4: -9.59
5: 0 5: -9.61 5: -8.98
6: -7.32 6: 0
7: 9.83 7: -9.08
8: 0 8: 9.83
R44 is standing up next to the transformer.
u5 U15 U6
1: 0 1: 0 1: -9.59
2: 8.33 2: -4.04 2: -9.59
3: 8.26 3: -3.41 3: 9.84
4: -9.61 4: 0 4: -9.59
5: 0 5: -9.61 5: -8.98
6: -7.32 6: 0
7: 9.83 7: -9.08
8: 0 8: 9.83
R44 is standing up next to the transformer.
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