Here's an intermediate update @Markw4
While I was getting both PSU ready to be switched, I decided to d some continuity measuring on the traces/solder points of both PSU's. Then I noticed something. At the PSU of the working BeoLab I measured continuity where I did not expect to get it. When I measured the same points on the 'troubled' BeoLab, there was no continuity between them. Here's the pictures ...
Left picture is the PSU from the working BeoLab.
Right picture is the PSU from the troubled BeoLab.
In the red circle you see the the two solder points I compared on both PSU PCB's. I looked very close, but between these two solder points, there seems to be no connecting copper trace. When I looked close, it seems the left pin is bent and because of that, touching the other solder point. See close-up picture below. So what seems strange, that this is probably an accidentally bent pin that accidentally touches another pin.
I believe these pins involved are of the stand-by transformer. This one is always on to enable the Auto stand-by to switch from stand-by/Off to On when music is coming to the RCA input.
I am not sure if this matters (or if its part of the situation). Especially since the bent pin with unexpected continuity measurement is on the PSU of the working BeoLab. But nevertheless it is worth to mention.
Question: what do you think of this?
While I was getting both PSU ready to be switched, I decided to d some continuity measuring on the traces/solder points of both PSU's. Then I noticed something. At the PSU of the working BeoLab I measured continuity where I did not expect to get it. When I measured the same points on the 'troubled' BeoLab, there was no continuity between them. Here's the pictures ...
Left picture is the PSU from the working BeoLab.
Right picture is the PSU from the troubled BeoLab.
In the red circle you see the the two solder points I compared on both PSU PCB's. I looked very close, but between these two solder points, there seems to be no connecting copper trace. When I looked close, it seems the left pin is bent and because of that, touching the other solder point. See close-up picture below. So what seems strange, that this is probably an accidentally bent pin that accidentally touches another pin.
I believe these pins involved are of the stand-by transformer. This one is always on to enable the Auto stand-by to switch from stand-by/Off to On when music is coming to the RCA input.
I am not sure if this matters (or if its part of the situation). Especially since the bent pin with unexpected continuity measurement is on the PSU of the working BeoLab. But nevertheless it is worth to mention.
Question: what do you think of this?
Okay. Its possible three was a little solder growth or migration that finally bridged the gap between the leads. That could account for why the problem started up by itself. I would probably remove the bridge, and straighten up the folded over lead on the left so isn't so close to the right lead. Separating them may fix it, or the bridge may have caused some damage that still needs fixing.
Odd. Maybe the good one will develop a buzz with the bridge removed. Do you have a schematic for the power supply?
