[HELP] SX-939 - No output audio

[joaokmo]

is that +- 49.7v ?

Exactly +48.8v at the NPNs and -48.8 at PNPs output transistors. And 31.73v at the pins 19/20.

 

[petehall347]

compare voltages .. q1 q2 .. q3 q4 .

 

[joaokmo]

compare voltages .. q1 q2 .. q3 q4 .

49.7v, maybe they're fine in voltage tolerance? I took a look at the schematics now and it says it should be 48v...

 

[petehall347]

sorry i didnt realise outputs had same numbers as the input differential pairs that control the dc offset .
they are shown on the left side of amp schematic .

 

[joaokmo]

sorry i didnt realise outputs had same numbers as the input differential pairs that control the dc offset .
they are shown on the left side of amp schematic .

I was unable to measure it correctly. It oscillates wildly between 7v ~ 47v + and - on all. I don't know what to do. =/

 

[petehall347]

pre out main in jumpers removed ?

 

[joaokmo]

pre out main in jumpers removed ?

They're attached.

 

[petehall347]

try without to rule out things

 

[craxx6969]

Hi, Pete. Checked it now. Reaching 49.7v on all output transistors. Thanks!

Just an FYI, when responding with a voltage, make sure to list it either as a positive or negative voltage. It is most important for follow up. Another important point is to follow the instructions and report. Wait for the next instructions before proceeding.