I took in the Hammond Organ amp conversion ( now a BF Deluxe reverb with added gain stage , but no Choke ) and once I fixed its main issue and got it on the O-scope I see the whole output wave form dancing up and down at whatever frequency I pump into it .
This takes place at any level of output also, from 1/2 watt to its full clipping power of 32 watts.
Anyone here ever seen such before and fixed it?
Tonight I will scope it out starting at the first gain stage to see if this through out the amp.
Thanks in advance for any help.
Output wave form dance.
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Stevem
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Output wave form dance.
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Re: Output wave form dance.
I've not seen what you describe before. I've seen outputs modulated with line frequency, but not with the input freq. I'm betting on a circuit ground problem. I assume your scope ground is good. Does the percentage of modulation increase with increased gain?
Schematic?
Schematic?
Tube junkie that aspires to become a tri-state bidirectional buss driver.
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wpaulvogel
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Re: Output wave form dance.
A video clip would help also.
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Stevem
- Posts: 5144
- Joined: Fri Jan 24, 2014 3:01 pm
- Location: 1/3rd the way out one of the arms of the Milkyway.
Re: Output wave form dance.
Well I had to get the amp back to owner with that issue taking place as he needed it for recording , so no video can be taken.
That being said just invasion the whole wave form looking like it was riding on another unseen wave form that was running thru it with it and following input signal frequency.
I would have loved to have got it solved but the time was not to be had.
I will likely see the amp again as it has a oversized power transformer and can push out over 30 watts peak and its dinky original output transformer is destined to burn up sooner then later!
That being said just invasion the whole wave form looking like it was riding on another unseen wave form that was running thru it with it and following input signal frequency.
I would have loved to have got it solved but the time was not to be had.
I will likely see the amp again as it has a oversized power transformer and can push out over 30 watts peak and its dinky original output transformer is destined to burn up sooner then later!
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Re: Output wave form dance.
If the OT secondary was not connected to chassis ground your scope display would dance.
Re: Output wave form dance.
Sluckey, wouldn't that dance be at the line frequency?
Tube junkie that aspires to become a tri-state bidirectional buss driver.
Re: Output wave form dance.
It may be that an incomplete NFB loop (ie from a missing OT secondary 0V connection) might have a weird effect such as that described.
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