Bias Diodes Marantz 1030

[Keith Baran]

Hello all

I’m re-assembling a re-capped P700. There are two diodes, PT# HV0000212 SV-3A at H005/H006 locations on the 700 PCB. On one side has a small bump on it and the other side is flat. When I originally removed these from the heatsink I never removed the thermal paste from them, now that I am putting it back together I realize the greased side is the side with the bump on it. When I clamp them to the heat sink there is not much surface area on the heat sink, they don’t sit flat.. My first inclination is to flip them over but that’s the way they were originally mounted. Another post commented that these are very brittle and are not available anymore so I don’t want to handle them too much. Any suggestions??

 

[ChrisMarantz]

One way to think about this is: The clamp that hold the diode in place is up against the flatter side of the diode. Since the clamp is screwed to the heat sink, it will heat up along with the heat sink.

I have rebuilt many 1030's and 1060's and I can;t say that I ever noticed this, perhaps i wasn't looking for it. Since its been that way for decades, i doubt it's a real issue - Chris

 

[Keith Baran]

Thanx for your input, if that's the case would it be prudent to add a little thermal grease to the clamp side also?

 

[creeve]

Too funny....I have been asking myself the same question for a few days now. Just finished putting a 2220 back together and I believe the amp board is almost the same as your 1030, anyway the diodes are the same. I have one going in each direction. I opted to leave it since that little troublemaker has an uncanny ability to break. I see no ill effects or imbalance in bias on either side, so that leaves me to believe it's not too critical. Just be careful with them.

 

[ChrisMarantz]

Thanx for your input, if that's the case would it be prudent to add a little thermal grease to the clamp side also?

Sure, a little swipe of thermal grease would be fine - Chris