Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: mini612 on September 24, 2024, 11:14:00 am
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Hello everyone, before I continue to work on this amp, I want to see if I can some help on this amp. I am currently working on an Egnater Tweaker 15. I don't know the history of this amp but the original PT went out so it needed a new PT. I've decided to connect with a PT I have on hand. The PT I use high voltage is 300-0-300 which is around the specs of the original PT.
When the amp is on, the blue indicator light comes on, the filament of the tubes lights up. The issue is, there is very low volume through my speaker cab. In order to barely/faintly hear it, I would need to max the "gain" and "master volume" pots. The sound/noise coming out is distorted, probably due to the level of the gain and mv pots being at full.
I checked the OT, and it is good. All the tubes I used are in good functional condition. Grounding points appears to have good contact and showing continuity. Input and Output jacks are good. All fuses shows good contact and continuity.
Voltages at Tubes:
6v6's, both same voltages.
Pin/Vdc
1 - 27
2 - 43
3 - 367
4 - 348
5 - 0
6 - 0
7 - 43
8 - 26
Pre-Amp:
1 - 237
2 - 0
3 - 2
4/5/9 - 43
6 - 210
7 - 0
8 - 1.5
Loop:
1 - 313
2 - 24
3 - 76
4/5/9 - 43
6 - 188
7 - 0
8 - 1.2
P.I:
1 - 326
2 - 19
3 - 22
4/5/9 - 43
6 - 176
7 - 13
8 - 22
Additional info:
B+ = 372v at fuses (C25 and C27)
QC5 = 329v
QC4 - 347v
QC2 - 328v
Thanks
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Does the amperage spec on the new PT match or higher than the Original PT?
Or do you know that the new PT drove an equivalent tube set as your tweaker??
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Does the amperage spec on the new PT match or higher than the Original PT?
Or do you know that the new PT drove an equivalent tube set as your tweaker??
The new PT spec is similar to the original Tweaker that drove similar tubes (EL84 PP with 12ax7 preamp and PI). I also tried with another PT that is for a Marshall 18 watt, and the Tweaker was doing the same thing.
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Looks like 1/2 of your PI isn't conducting.
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Check AC voltage between pins 4-9 and 5-9 of your PI.
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Check AC voltage between pins 4-9 and 5-9 of your PI.
Hi AlNewman, thanks for responding. I checked and it's 6vac
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Looks like 1/2 of your PI isn't conducting.
Thanks for suggesting this. I was also thinking that the PI stage is not functioning as it should. I'm at work at this time, but I will certainly focus around this stage when I get home.