If you trace the wires from pin 8 of the power tubes to the front panel, there should be a test point for each tube wired to the socket. I think we used a couple of pins for the feedback loop, and a couple for the bias test points. I'm thinking 11.00 and 1.00 pins facing front, but it has been some time. I would consider lower bias (the new tubes are not as good as old tubes were for running hard and hot. Maybe more like 30 ma each.
Thanks for the kind words, glad I could be of service.
Thanks for the kind words, glad I could be of service.
Just a brief update. Per everyone's instructions I was able to identify the bias test points (5 o'clock and 6 o'clock positions). The bias was tolerably well set around .3-3.5 volts but I did take the time to set them all at exactly .3 volts. (Those little trimpots are delicate to adjust). Took the amp into a guitar store and the owner had sufficient knowledge to confirm that I had set the bias at the suggested range. Have them hooked up to Klipsch KG4s. Think I may try a PAS preamp rebuild as my first DIY project. Thanks to everyone.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.