Memphis 16-MCD1500 repair help

[Lerch256]

The resistance readings I gave earlier was incorrect..

LM361 pin 3 to pin 13 of TL074C is 2.183k
LM361 pin 3 to pin 14 of TL074C is 6.04m

LM361 pin 4 to pin 13 of TL074C is 6.04M
LM361 pin 4 to pin 14 of TL074C is 14.83k

Sorry about that

 

[Perry Babin]

What was the reason for the error?

 

[Lerch256]

It was my error I counted wrong on the TL074

 

[Perry Babin]

Did you have the proper pins (13 and 14) bridged on the TL074?

 

[Lerch256]

I still had 13/14 bridged on the first reading so I read off 13/14 and pin 12 .. so I removed the bridge and updated the readings thanks

 

[Perry Babin]

When you bridge 13 and 14 (with solder or a wire), what is the DC voltage on pins 12 and 13/14 of the TL074?

 

[Lerch256]

I had those two pins bridged

 

[Lerch256]

There is no voltage present on 13/14 bridged or pin 12 of the TL074..

I do have 11.87 volts on pin 4 and 0.65v on pin8 also -12.20 on pin 11 of TL074

Pin 3 of LM361 has -8.16 same on the R165 resistor going to the LM361

R165 that's hooked to TL074 HAS 0.03V ON IT

 

[Lerch256]

I appreciate the help and guidance your patiently giving to help me resolve and maybe understand this repair

 

[Perry Babin]

DCV on pin 4 of the LM361?

 

[Lerch256]

5.87 v

 

[Perry Babin]

DC voltage on pins 8, 9 and 10 of the TL074?

 

[Lerch256]

There is no voltage on 8,9, or 10 on TL704

 

[Perry Babin]

Copy and paste the following list and fill in the blanks. If there is no blank space after the colon, add one between the colon and the numbers you enter. It makes it much easier to read.

LM361 DCV on all pins:
Pin 1:
Pin 2:
Pin 3:
Pin 4:
Pin 5:
Pin 6:
Pin 7:
Pin 8:
Pin 9:
Pin 10:
Pin 11:
Pin 12:
Pin 13:
Pin 14:

 

[Lerch256]

LM361 DCV on all pins:
Pin 1: 11.90
Pin 2: 0
Pin 3: -8.21
Pin 4: -9.36
Pin 5: 0
Pin 6: -11.35
Pin 7: 0
Pin 8: 2.67
Pin 9: 2.67
Pin 10: -2.26
Pin 11: -10.34
Pin 12: 0
Pin 13: 2.66
Pin 14: 2.66

 

[Perry Babin]

Remove the LM361 (no output driver boards installed) and repost the pin voltages that have changed significantly.

 

[Lerch256]

LM361 DCV on all pins:
Pin 1: 11.93
Pin 2: 0
Pin 3: 0
Pin 4: 0
Pin 5: 0
Pin 6: -12.2
Pin 7: 0
Pin 8: 3.15
Pin 9: 3.15
Pin 10: -2.27
Pin 11: 3.15
Pin 12: 0
Pin 13: 3.15
Pin 14: 3.15

 

[Perry Babin]

It appears to be defective.

 

[Lerch256]

Alright I'll order one and replace and report back thanks

 

[Lerch256]

Hello.
It's been awhile .. finally got the ic in the amp got drive signal on the output .. then I put the amp back in the case after installing all the output fets .. it has the protection light on .. so I removed it .. the power supply is in protection mode .. one one side of the transformer I have 12.1 v which is what my power supply reads on the output.. on the other side of the transformer I get 2.5v

The amp keeps trying to turn on it'll flash the green line and go back to red.. it'll fluctuate the voltage from 12.1v to 11.5v .. over and over ..any ideas thanks