Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: plexi50 on May 04, 2024, 11:03:52 am
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I have put a new cap can in the chassis and the amp is loud and proud. I have great oscillation on the intensity and Speed pots. But no Vibrato in the signal path. I am looking at the varistors. One has 278vdc in & 160vdc out the other side. The other has 160vdc in & 48.8 vdc on the other lead. Does this sound like i have a bad varistor?
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Varistors / Caps
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I have great oscillation on the intensity and Speed pots.
How do you know? Exactly how did you verify that?
But no Vibrato in the signal path. I am looking at the varistors. One has 278vdc in & 160vdc out the other side. The other has 160vdc in & 48.8 vdc on the other lead. Does this sound like i have a bad varistor?
No. The voltages are different because one varistor is connected to the plate and the other varistor is connected to the cathode.
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I have great oscillation on the intensity and Speed pots.
How do you know? Exactly how did you verify that?
But no Vibrato in the signal path. I am looking at the varistors. One has 278vdc in & 160vdc out the other side. The other has 160vdc in & 48.8 vdc on the other lead. Does this sound like i have a bad varistor?
No. The voltages are different because one varistor is connected to the plate and the other varistor is connected to the cathode.
I have good voltage fluctuation on the pots and the .01 Edit: 005 caps near the pot's circled in red. Turn the pots down and the fluxuating voltage goes away. YES THE ONE VARISTOR IS GOING TO THE CATHODE.. I FIGURED THAT MUCH. DAM CAPS.
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Got these varistors 10 or more years ago if they are needed.
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I would just replace all these old caps. But the owner would rather just have the amp working and playing nicely than change anything else. That is self defeating. The whole magic of this amp is the Vibrato! I'm not finding any leaky caps. I cant settle for this amp having no vibrato! :BangHead: :BangHead: :BangHead: :BangHead: :BangHead: :BangHead: I'm a glutton for punishment!