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tranny problem, looking for advice on a power amp
john11
post Mar 23 2013, 08:47
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Hi and thanks for reading this post.

My amplifier has been playing up on me and i noticed a swollen capacitor which i replaced with a new one of the same voltage and capacitance.

When reassembled the amp would not work at all, after a few hours of experimentation i noticed a row of transistors which are clipped onto the metal chassis of the amp, obviously this was done by the manufacturer to keep the transistors cool and i had to unclip these to get the board out.

When the transistors are clipped back onto the chassis of the amp so in effect they are all sharing one large heatsink the amp does not work, i gave each transistor its own heatsink and now the amp works fine.

Can anyone tell me what is going on.

Many thanks in advance. John.
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john11
post Mar 25 2013, 08:36
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Hi. Thanks for the reply, much appreciated.

Pretty sure the cap is ok as the board had a shaded half which indicates the negative terminal. The amp works when the transistors are separated off from each other and have their own heatsink, so i think the manufacturer may have picked a thermal paste which has an insulating effect.

The paste i am using is silver paste which is more expensive and apparently conducts heat away better, but perhaps conducts electricity better.

Is there anything i can buy which will insulate the transistors from each other. I popped open another amplifier and noticed the transistors have what looks like a piece of paper behind them, but the paper feels soft and silky to the touch so am not sure what it is.

Many thanks. John.
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