77seriesIII wrote:ok as promised here are voltages WITHOUT 300B's installed.
V1 6SL7GT New Issue Tung Sol Pins:
1) 0v
2) read 200v Supposed to be 147v
3) read 2.3v Supposed to be 1.8
4) 0v
5) read 208 Supposed to be 147
6) read 2.3v Supposed to be 1.8v
7) & 8) read 6.29vac
These numbers are A-OK. The plate voltages are higher without the main load attached (ie the 300Bs).
77seriesIII wrote:V2 6AX5GT CBS
1) 0v
2) 6.18vac
3) 332v Supposed to be 324vac
4) 0v
5) 330v Supposed to be 324vac
6) 0v
7) 6.18vac
8) 432v Supposed to be 333v
Ditto. These numbers are also A-OK. The B+ is about where I would expect it without the 300Bs.
77seriesIII wrote:V3 & V4 300b. I'm just testing the B+ and heater
1) & 4) 7.3v REMEMBER NO Tube, just measuring across with probes
If anywhere this is where I may have screwed up
OPT is wired to Pin 2 if you are looking from the bottom up or Pin 3 if you are looking from top down V3 = 432 V4 = 431 There are NO 300B tubes attached/installed during these measurements
Again, this looks normal considering no 300Bs. The rest of your voltages look to be normal, too. Thanks for taking the time to list those.
The 900 ohm bias resistor network biased those 300Bs a little to aggressively with the SS rectification. Even though you had switched back to the 6AX5GT rectifier, the damage could have been done already and one may failed, thus killing C5 with the B+ across it. One shorted 300B would drag down the whole system, so try one 300B at a time, and swap sides with one at a time, too. I am guessing one tube will bias up normally. Record the voltages at TP1 and TP2 when you do this test. But if it makes a racket, pull the plug immediately.
Check out Lee's thread in this forum. An almost identical event happened to him.