[tomchr]

If I measure between the characters I get no values only if I connect Plus to one of the characters I get some.

In that case I bet you have a faulty connection between the transformer and the rectifier.

Tom

 

[TrollDragon]

Since there are two bridge rectifiers in there I am assuming a split rail DC supply. Putting your meters black probe on the GND pad next to the upper bridge you should get a + voltage by putting your red probe on the + leg of that bridge. If you found 0V on the + leg of the lower bridge try putting your probe on the - leg and see if you get a - voltage reading. Or vice versa depending on how the bridges are wired, I don't have a schematic.

That power circuit should look similar to this (ignore the component values), it is just to show how those two bridges are possibly connected to give you the +/- voltages.

 

[tomchr]

There could also be two separate supplies. One for each channel.

Tom

 

[Deleeh]

Okay,
thank you both.
What I don't understand is that the left channel didn't work when I short-circuited the oversized capacitors.
And then it was quiet.
I put the failure of the left channel down to a bad connection.

Now I replace the same capacitors with the same values and size and only the bridge rectifier goes bye-bye?

So maybe it was already defective before?

I measured it again as you said @TrollDragon.
One of the judges works and the other one doesn't.

I'll give it a chance now before it ends up in the bin.
Now the question is what should I look for when choosing a component?
Apart from the fact that it says 2w10 on it, I can't do anything.

 

[Deleeh]

Found them here,is it the right?
https://elteile.de/aktive-bauelemente/brueckengleichrichter/971/brueckengleichrichter-2w10
Datasheet is under Information

 

[TrollDragon]

I measured it again as you said @TrollDragon.
One of the judges works and the other one doesn't.

Are you getting AC voltage on the ~ pins of each bridge?

 

[tomchr]

Found them here,is it the right?
https://elteile.de/aktive-bauelemente/brueckengleichrichter/971/brueckengleichrichter-2w10

That's the one.

Are you getting AC voltage on the ~ pins of each bridge?

Great question. I would verify that first. No AC going in, no DC coming out. That wouldn't be the fault of the bridge. That would be a bad connection to the transformer.

You need to measure AC voltage from one ~ (AC) pin to the other ~ (AC) pin. If you have AC voltage there but no DC from + to - (the other two pins on the bridge), the bridge is dead.

I don't understand the bit about "shorted the oversized capacitors". If you shorted the supply capacitors while the amp was on, you definitely blew the rectifier bridge.

Tom

 

[Deleeh]

So it shows actually.
There is only something when I measure plus with minus at the bridge rectifier.
Nothing is present between ~~.

 

[tomchr]

If there's no AC voltage (make sure the voltmeter is set to AC) between the two AC pins on the bridge, the connection to the transformer is the problem. It could also be the transformer itself, but that's pretty darn unlikely.

Tom

 

[tomchr]

I'd redo the solder job on those wires. Especially the solder joint on the top green wire looks unhealthy. It looks like you need to give it a bit more dwell time so the solder can flow correctly.

Tom

 

[TrollDragon]

I was about to say the same thing about the green wire. There should be AC voltage on the brown wires and the green wires.

There is a solder bridge on one of your caps that needs to be cleaned up as well.

 

[TrollDragon]

There is also some nasty soldering on the #3 tube pin near the headphone jack. Is that the tube that doesn't light up? Little Dot usually pulls the LED power from the heater source, so if that tube and the LED both don't work I'd say you have lifted or broken a trace on the board for that tube.

Soldering is not like working with a hot glue gun, it takes precision. Judging by the melted capacitor tops and the corner of the headphone jack, you need more practice.

 

[Deleeh]

Okay, I'll check it out and fix it.
Thanks guys.

 

[Deleeh]

There is also some nasty soldering on the #3 tube pin near the headphone jack. Is that the tube that doesn't light up? Little Dot usually pulls the LED power from the heater source, so if that tube and the LED both don't work I'd say you have lifted or broken a trace on the board for that tube.

Soldering is not like working with a hot glue gun, it takes precision. Judging by the melted capacitor tops and the corner of the headphone jack, you need more practice.

Hmm yes, that doesn't suit me either, I couldn't do it any better.
I will try to fix it again.
If the conductor path is broken, how can I fix it?

 

[Deleeh]

There is also some nasty soldering on the #3 tube pin near the headphone jack. Is that the tube that doesn't light up? Little Dot usually pulls the LED power from the heater source, so if that tube and the LED both don't work I'd say you have lifted or broken a trace on the board for that tube.

Soldering is not like working with a hot glue gun, it takes precision. Judging by the melted capacitor tops and the corner of the headphone jack, you need more practice.

Yes, this is the side with the tube