Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: plexi50 on August 16, 2024, 12:41:14 pm
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I have a M14A Rickenbacker and the intensity is some what weak.Does not always kick in when pushing the foot switch. The foot switch is good and clean and passes a continuity test for good function.No schematic but looking for a resistor or cap value that may improve it's intensity. Bias is +15.87 vdc.
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Did you try a new tremolo tube ?
Often you have to replace these 3 capacitors for time base C17,C19 C20 to fix a tremolo issue.
This is may not the right schematic ( it is a Rick B115 ) but most tube amp's tremolo are built this way .
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I put all new strong tubes in it. Now the amp is squealing.The grid of V1 is not producing sound now on the tremelo jack when i engage the foot switch,Guess in going to change some coupling caps. All resistors read good spec value. Frustrating!
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Your "strong " tube , or other could be microphonic ?
Tube tester can't show if tube is microphonic .
Non need to replace other caps than the one I show you.
To work on amp, you need basic tools ; signal generator and scope.
And some electronic knowledge.
No schematic ? You must have very good tube amp knowledge and experience.
Without basic tool you can only fix very easy problem, it is not this one.
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Ok i took the day off yesterday. I have a signal generator and will use it today. If i so much as put my fingers any where near V1 tube wiring any amp signal disappears. Oscillating coupling that area bad. Will get back here later this afternoon or sooner. Thanks much again.
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To work on amp, you need basic tools ; signal generator and scope.
And some electronic knowledge.
No schematic ? You must have very good tube amp knowledge and experience.
Without basic tool you can only fix very easy problem, it is not this one.
Latole, you see how many posts plex50 has?
He knows what he's doing, he's fixed many, many amps.
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See the two white wires? One on the tube and one on the electrolytic 25uf cap on the board? That's the foot switch for the tremelo.
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Problem is i am getting older now and have a sense of slight dementia. I forget what i am doing sometimes. I hate it.
To work on amp, you need basic tools ; signal generator and scope.
And some electronic knowledge.
No schematic ? You must have very good tube amp knowledge and experience.
Without basic tool you can only fix very easy problem, it is not this one.
Latole, you see how many posts plex50 has?
He knows what he's doing, he's fixed many, many amps.
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To work on amp, you need basic tools ; signal generator and scope.
And some electronic knowledge.
No schematic ? You must have very good tube amp knowledge and experience.
Without basic tool you can only fix very easy problem, it is not this one.
Latole, you see how many posts plex50 has?
He knows what he's doing, he's fixed many, many amps.
Latole, you see how many posts plex50 has?
Answer ; I dont remember to see one
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He knows what he's doing, he's fixed many, many amps.
Good to know , Thank's
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Got it! All this time there was a tiny blob of solder connecting 2 resistors (470K) that were not suppose to be there.The wiring someone did on this is pretty shabby. Put in a few Mallory M150 tone caps. I will tell you there are times when it turns out to be the most simple thing it makes you feel stupid.But at the same time you conquered it and did not give up. That's not an option. Amen!
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Good job Plexi. :icon_biggrin:
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Thanks all for your comments. Doing this everyday is what drives me. There is no quitting. There is no (I cant)