Hello everyone,
I recently aquired Beolab Penta mk3 type 6631. I refoamed them, recapped both of them, recapped the crossover, replaced those big filter capacitors and put in a new relay. After a lot of torture with this speakers, they still won’t turn on.
On speaker no.1:
I did a recap and had a few lifted pads which I repaired with jumper wire and tested with continuity mode, everything was ok. I also tested the transistors (6 big ones, 2 smaller ones, and 2 of those BF858) which were also ok and I also didn’t forget to put insulators on 6 big ones. I also measured everything on the input board and cleaned the contacts for selecting modes. I checked for cold joints and to my eye I found none. I made sure that capacitor polarities are as they should be. When I tried to turn them on, they clicked green on both AUTO, L and R, but then after a few seconds they went red and didn’t turn green anymore, and DC on output was 300mV and didn’t raise/lower when I tried moving the trimpot. A blessing in disguise, amp wasn’t connected to the tower at that time so speakers didn’t get damaged from so much DC. Does anyone have any idea what could underlying problem be? What should I measure? Are there some diodes or little transistors that are known to cause problems?
On speaker no.2:
After the recap this wasn’t turning on no matter what. LED light didn’t light up and relay didn’t click. On this one I didn’t inspect the input board nor did I clean the contacts. After the recap I also had 2-3 lifted pads which I fixed with jumper wire and measured with continuity mode, everything was ok. In the midtime of the second disassembly, live touched neutral (don’t ask me how that happened), the fuse blew, but thankfully transformer and transistors (6 big ones, 2 smaller ones and 2 BF858) survived. Does anyone have any idea why this one wasn’t turning on in the first time? Could it also be some smaller transistor or diode causing a problem?
I would be thankful for any sort of help
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