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This is a Fender Deluxe Reverb amp with new TungSol 6V6GT's.In the photo, the red spots look worse than they actually are because of the time exposure. It's a dull red glow.
The tubes are within their dissipation limits. Plate/screen voltage is around 450V, and in the photo they are pulling 24mA each. Negative
bias is -40V.I have to drop plate current down to 12 mA to make the hot spots disappear.
It looks to me like the electron beam is being concentrated on this one area of the plates. The tubes test normal.
Any ideas?
Edits: 06/08/17
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Topic - Hot spots on 6V6 plates - Alpha Al 10:19:40 06/08/17 (20)
- RE: Hot spots on 6V6 plates - awesterner 02:08:11 08/28/17 (0)
- Try a 5r4 rectifier - DAK 13:53:08 06/08/17 (2)
- RE: Try a 5r4 rectifier - Alpha Al 15:05:52 06/08/17 (1)
- RE: On the other hand.... - DAK 22:08:47 06/08/17 (0)
- RE: Hot spots on 6V6 plates - 6bq5 13:28:25 06/08/17 (0)
- RE: 450v plate and screen? - DAK 10:55:09 06/08/17 (14)
- RE: 450v plate and screen? - Alpha Al 11:25:37 06/08/17 (13)
- RE: 450v plate and screen? - Audio Pete 14:54:15 08/23/17 (0)
- RE: 450v plate and screen? - Audio Pete 14:49:56 08/23/17 (0)
- RE: 450v plate and screen? - kmolles 15:23:28 06/08/17 (0)
- RE: 450v plate and screen? - Jim McShane 13:39:35 06/08/17 (9)
- RE: 450v plate and screen? - Alpha Al 13:56:49 06/08/17 (8)
- RE: 450v plate and screen? - Tre' 18:49:07 06/08/17 (3)
- RE: 450v plate and screen? - Alpha Al 07:57:11 06/09/17 (2)
- RE: 450v plate and screen? - Tre' 09:35:31 06/09/17 (1)
- RE: 450v plate and screen? - FenderLover 07:27:23 06/12/17 (0)
- RE: 450v plate and screen? - Jim McShane 14:21:23 06/08/17 (3)
- New development - Alpha Al 15:11:00 06/08/17 (2)
- RE: New development - Jim McShane 16:27:54 06/08/17 (1)
- Screen resistors - FenderLover 17:53:11 06/08/17 (0)