Fixed my Quadraflex 650FET R receiver

rhtatro · 25th April 2007, 01:41 AM

Picked up a cheap ($28) stereo receiver with lateral Hitachi mosfet finals off of ebay but it had a problem....would distort badly at low volume levels and would require both A and B speaker switches to be turned on. Protection light would come on.
I assumed it was bad finals, so I ordered 4 new ones, 2Sk134 and 2SJ49 TO-3 cans, 2 each.
They finally arrived and I installed them, it has sockets that makes it easy, along with a bit of cpu thermal grease.
I powered her up and now it sounds just beautiful and I can crank it, the heatsink is much warmer than before, and all 4 big white bias resistors get warm as opposed to only one before.
It sure is fun to rescue a piece of vintage gear and at low cost also.

It still has one burned dial light, 8 volt at 0.34 amp, any ideas where to get one or more? How about a service manual or schematic?
Thanks, Bob Tatro

25th April 2007, 01:41 AM	#1
rhtatro diyAudio Member Join Date: Mar 2007	Fixed my Quadraflex 650FET R receiver Picked up a cheap ($28) stereo receiver with lateral Hitachi mosfet finals off of ebay but it had a problem....would distort badly at low volume levels and would require both A and B speaker switches to be turned on. Protection light would come on. I assumed it was bad finals, so I ordered 4 new ones, 2Sk134 and 2SJ49 TO-3 cans, 2 each. They finally arrived and I installed them, it has sockets that makes it easy, along with a bit of cpu thermal grease. I powered her up and now it sounds just beautiful and I can crank it, the heatsink is much warmer than before, and all 4 big white bias resistors get warm as opposed to only one before. It sure is fun to rescue a piece of vintage gear and at low cost also. It still has one burned dial light, 8 volt at 0.34 amp, any ideas where to get one or more? How about a service manual or schematic? Thanks, Bob Tatro

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