Phase Linear 300 sII Trimpots

[bigdano123]

Are trimpots pretty much equal other than values and physical dimensions etc? I have recapped and replaced all semiconductors in the unit, along with all resistors but output relays would unlock after about 30 seconds after power on and would not lock up again until the capacitors had drained after unplugging the amp. I measured the resistance of the trimpots and found them both to be open. I'm trying to figure out what I should replace them with. Thanks for any assistance.

 

[llwhtt]

Aren't those the strangest trimmers you've ever seen. The last 300 I worked on had bad trimmers also plus they are 5K which is too much resistance making the adjustment very touchy. I "think" I used 1K CTS trimmers which can be adjusted with your fingers. The CTS trimmers are obsolete but Digikey might have some left. 15mm Pihers would work if you can find the thumbwheel type.

Craig

 

[bigdano123]

Thanks. I'll see what I can find.

 

[llwhtt]

If you use the Piher PT15 series trimmer the add-on thumbwheel is part number 5371. Mouser has both in stock.