Avalon vt-737sp

[pucho812]

Thanks for the info. That was my plan and to repair any damaged traces. Since the unit is more than 10 years old a recap was also on the list.

I’ve had more resistors fry from shorted caps on those boards then bad transistors but as always check them.

 

[Jdm5149]

U have the right guys with your questions. They helped me immensely. Almost have mine 100%.

 

[TheseGoToEleven]

Not sure this helps but here's an old thread with a virtually identical failure involving Q9 and many of the same resistors.
https://groupdiy.com/threads/avalon-737sp-burned-resistors.45820/

 

[pucho812]

Not sure this helps but here's an old thread with a virtually identical failure involving Q9 and many of the same resistors.
https://groupdiy.com/threads/avalon-737sp-burned-resistors.45820/

FYI That was before my time on the battlefield in the Avalon fox holes.

 

[Jdm5149]

Hey there. I bought some spares and was wondering if these could be causing the meter to pin hard right now. Pretty much that’s all I need to fix

 

[pucho812]

View attachment 135440Hey there. I bought some spares and was wondering if these could be causing the meter to pin hard right now. Pretty much that’s all I need to fix

Spare what? Diodes?

 

[Jdm5149]

Sorry. I meant the relays

 

[Jdm5149]

K7 k8 k9

 

[pucho812]

K7 k8 k9

Did you pull the op07 opamp?
It’s under the 5600-7372 card, which should be the I/o card at the rear of the unit left of the psu by the xlr’s?

Did you test and check that opamp?

 

[Jdm5149]

K will try today. Thanks

 

[Jdm5149]

K. With one side to ground I hit the following
These readings are shown as looking at pins in this pic;
-17.93. 0
-7.94. -17.28
-9.32. 16.35
0. 0.

I measured one side to ground on chassis. Is this correct or should I use the ground on chip itself ?

 

[pucho812]

Did you pull the chip as requested?
Take it out and see what happens.
Seat it back in and see.
Looks like your getting around +/-17 which would be ok

 

[Jdm5149]

K will try tomorrow. Thanks again. Why can I adjust the meter for the compressor portion but then it pins in reg mode. ??

 

[pucho812]

K will try tomorrow. Thanks again. Why can I adjust the meter for the compressor portion but then it pins in reg mode. ??

Because it’s getting signal from different places depending on which mode

 

[TheseGoToEleven]

FYI relays K7/K8/K9 have nothing to do with the VU meter. Relay K13 is the one that selects the signal to the VU meter.

However, with the “meter” button out (unlit), it looks like you already have a problem earlier in the signal path at opamp U1. That opamp is outputting -17.28 volts at pin 6, which is nearly the same as the negative power supply rail.

So I think pucho is right to suggest pulling that chip and testing it separately or just replacing it with a new one & retest.

 

[Jdm5149]

Thanks

 

[Jdm5149]

K. Chip is soldered in so reseating is not possible. Should I check any areas before it reaches that chip

 

[Jdm5149]

Would u guys know replacement for that chip

 

[pucho812]

Would u guys know replacement for that chip

It’s an op07

 

[Jdm5149]

Newbie ? Op07 op amp ?