| Author: | Andrew Cockburn (registered user: 136 posts ) |
| Date: | Tue, Jan 03rd, 2012 @ 07:41 ( . ) |
I did some measurements as suggested - With just the Rectifier in, the B+ voltages were high as expected. Putting in V2 (power amp tube) however brought them plummeting down close to the figures I observed for all the tubes. Readings were slightly lower with all tubes in place, so I tentatively fingered the area of the power amp as the culprit. Sure enough, a careful check turned up a missing link into the biasing circuits. When I added the link, my B+ voltages were much healthier: B+1 - 330v B+2 - 321v B+3 - 312v B+4 - 307v B+5 - 305v Some of those are a little low but I am not going to argue over 14v :) Still no sound, but now the voltages are looking better I will break out the scope and trace the audio path through - thanks for getting me moving :) I also have another question - I took the upgraded Chappel OT option from Cliff's kit - does anyone know which secondary is which, impedance-wise? Thanks again! |
1/03/2012 @ 14:22------Stephen Keller --- 14 Users Online --- 74 Recent Unique Posters |