You can test without having to lift one leg.

 

ok, I mean yes I did

You can test without having to lift one leg.

I tried, the current was flowing to both side

 

What was the actual reading measuring both ways?

 

What was the actual reading measuring both ways?

do you mean from attached to the board? can't remember I can check now if you need to know

 

Yes and leave them attached to the board.

 

do you mean from attached to the board? can't remember I can check now if you need to know

D22 1.339-594. D21 1.321-606

 

OK. Now on the mixer board there are 12 diodes configured the same way I would like to check as you just did with D21-22.
They are D9 through D20. I am looking for a short or very low reading measuring both ways.

 

OK. Now on the mixer board there are 12 diodes configured the same way I would like to check as you just did with D21-22.
They are D9 through D20. I am looking for a short or very low reading measuring both ways.

to get the mixer board out will take me ages, it has plenty of knob that need to be out, and lots of screw to be unscrewed! Why should be something wrong with the mixer? I haven't touch it! Sorry I haven't see your last post, ok now I got it, but is this necessary?

 

Because of the way the circuit is designed.
Is there a connector on the mixer board that allows you to disconnect that board?

 

to get the mixer board out will take me ages, it has plenty of knob that need to be out, and lots of screw to be unscrewed! Why should be something wrong with the mixer? I haven't touch it! Sorry I haven't see your last post, ok now I got it, but is this necessary?

can it be done without get the board out? I'm not lazy, I haven't got the time at 3.30 i have to go work

 

can it be done without get the board out? I'm not lazy, I haven't got the time at 3.30 i have to go work

Because of the way the circuit is designed.
Is there a connector on the mixer board that allows you to disconnect that board?

Yes, it's connected with cables, can be easily disconnected

 

Good. I'm trying to isolate the -12 volt supply to see where the problem might be.
Can you get to those diodes without removing the mixer board?

 

Good. I'm try to isolate the -12 volt supply to see where the problem might be.
Can you get to those diodes without removing the mixer board?

I can't see where they are without removing it, also I remember that this board has no symbol on the component so very difficult to identify (for me) and the schematic we have is different from the design of this board, very confusing

 

OK. From the schematics if they are correct the -12 volt supply is only to power the op amps on the mixer and main amp pc boards.
You can reinstall the 10 ohm resistor R2, disconnect the mixer board and we will see if the -12 volt supply will work.
Other option is to order several 1K 5 watt resistors to use for testing later when they arrive.

 

OK. From the schematics if they are correct the -12 volt supply is only to power the op amps on the mixer and main amp pc boards.
You can reinstall the 10 ohm resistor R2, disconnect the mixer board and we will see if the -12 volt supply will work.
Other option is to order several 1K 5 watt resistors to use for testing later when they arrive.

ok, I'm going to reinstall the R2

 

OK

 

OK. From the schematics if they are correct the -12 volt supply is only to power the op amps on the mixer and main amp pc boards.
You can reinstall the 10 ohm resistor R2, disconnect the mixer board and we will see if the -12 volt supply will work.
Other option is to order several 1K 5 watt resistors to use for testing later when they arrive.

i got it done

 

i got it done

I suppose you wont to start the amp now?

 

Is the mixer board disconnected?

 

Is the mixer board disconnected?

yes