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From a string about a month ago, you and Mike S. were helping me with my ARC D70 shakey bias.
Your replied...
Does this drifting occur with only the phase inverter and output tubes?
If so, you've found the stage with issues. If the bias is still stable --- keep replacing signals tubes one-at-a-time from the PI back to the input stage. Until you get the drifting bias. This will, hopefully, narrow the issue to one stage. Then, you can concentrate on lead dressing and components within that stage.
Can you help...
I thought I had this problem licked after replacing some trim pots, but it is back again so suspecting something as simple as a cold solder joint, or other part I must've jostled. I'm hoping to narrow it down.
When you say to put signal tubes back in from "PI back to the input stage", do they have to go back in a specific order? Not sure what you mean my "PI"? Put in? Phase Inverter?
Also, can I put each signal tube in while the amp is on?
Thanks!
Jonesy
"I know just enough to get into trouble. But not enough to get out of it."
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Topic - "Ping" Fender Lover - Jonesy 13:57:50 05/12/14 (14)
- RE: "Ping" Fender Lover - Michael Samra 15:08:22 05/12/14 (13)
- RE: "Ping" Fender Lover - Jonesy 16:03:59 05/12/14 (12)
- RE: "Ping" Fender Lover - FenderLover 23:26:39 05/12/14 (11)
- RE: "Ping" Fender Lover - Jonesy 11:03:18 05/13/14 (10)
- I never even thought of the line voltage but that could very well be an issue if it varies. - Michael Samra 17:15:40 05/13/14 (9)
- RE: I never even thought of the line voltage but that could very well be an issue if it varies. - Jonesy 18:10:58 05/13/14 (8)
- Yeah, check the plate voltages when the bias reads differently - FenderLover 23:16:41 05/13/14 (7)
- RE: Yeah, check the plate voltages when the bias reads differently - Jonesy 10:56:23 05/14/14 (6)
- RE: Yeah, check the plate voltages when the bias reads differently - Michael Samra 15:17:07 05/14/14 (5)
- RE: Yeah, check the plate voltages when the bias reads differently - Jonesy 15:53:34 05/14/14 (4)
- Take several measurements at different times of the day - FenderLover 19:41:28 05/14/14 (3)
- I'm going to try a different DVM also... - Jonesy 21:50:19 05/14/14 (2)
- RE: I'm going to try a different DVM also... - FenderLover 01:01:00 05/15/14 (1)
- Ok. I'm good then... - Jonesy 20:51:51 05/15/14 (0)