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Yamaha PC2002M restoration

exwhyzed said:
what i need to do is unscrew the transistors from the other side, which will release them from the sockets?
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This. The two screws go through the heat sinks and screw into the sockets that are soldered to the pcb. No need to desolder the sockets. They should look like these from my M-4. I suggest taking pictures first so you know which TRs go where when you reassemble. I put little dots with a sharpie on them first, then take a pic. The sharpie wipes off easily later with a solvent. But be careful with solvents so you don't wipe off the lettering on the TR. You will also want to be careful with the mica insulator pads. Clean them off so you can reuse them. They are brittle and can crack.
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exwhyzed said:
@amr2 or anyone else, how do i release the DA board from the heatsink? I haven't worked on a unit with these types of metal can transistors that are mounted on the opposite side of the board before.

Do I unsolder the metal-spikes, that i think could be the transistors legs? If so, i can see how this will release the board. OR, are these metal spikes just the legs of sockets, and what i need to do is unscrew the transistors from the other side, which will release them from the sockets?

View attachment 2434921


View attachment 2434919
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No no no way..... just remove the metal strip cover on outer side of heatsinks and then pull out each TO-3 metal case power transistor. No need to desolder each socket.
 
Ok here's what i'm stumped with now. How can the PC2002 large filter capacitors be installed opposite to each other...so in series, but still bolted to a metal plate, which in turn is bolted to other metal plates/brackets and the amplifier outer case as well....and nothing is short circuiting?

pc2002 capacitors marked up.png
 
Because it is the common of the power supply (0V). The other two capacitors terminals are the positive and negative power rails.
 
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