Beepre problems

[tsingle999]

I fired it up to do voltage checks and everything looked good. All 8 LEDs lit up. 300b's lit.
Started measuring.
1. 4.7
2. 142
4. 8.16
5. -43

As I'm doing it I'm starting to smell smoke. I know 2 is way high. The led's on the a tube side dim. I unplug. The transformer on that side is burning up. I think the smell was from the transformer. All other components appear ok. I have gone through and don't see any mistakes. Any ideas? Thanks. Taran

 

[Paul Birkeland]

5 is supposed to be grounded.  If you have -43V at terminal 5, then you have a flaky solder joint on one or more of the black ground wires in the amplifier.  If terminal 5 is more like -43uV, then you have nothing to worry about.

Terminal 2 also tells us that there may be an issue with grounding, as the 300B plate isn't settling down to its intended operating voltage.

 

[tsingle999]

Ok so what i think happened is that the insulation on the black insulated wire that runs over the power transformer from pt terminals 3 & 4 got cut by terminal 6 on the power transformer. I believe the ground shield touched terminal 6. So i replaced that wire. I turned it on again but that side was dead. No lights on the c4s board. Maybe the pt is fried. Can I just retest it like I did early in the  manual?
Thanks. Taran

 

[Paul Birkeland]

Yes, you can unhook on of each pair of the wires on the PT-3 you'd like to check (other than the STP that comes from the power switch and IEC inlet), then measure your AC voltages carefully. 

If the AC voltages measure OK, then reconnect the 6.3V winding and measure POS-IN and verify that the tubes on that channel glow.

If you pass those two tests, then you have an issue with the HV supply.  Let me know if you get there, and we can continue breaking the chain to test each part on its own.

-PB