Hey, o recently got an old fender clone, replaced all the electros, and diodes since its 50 years old, and i get this sound
I believe the circuit to be AA769
Is this motorboating ? Could be caused by low grade elctros maybe ?
Fender clone weird sound, motorboating ?
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Fender clone weird sound, motorboating ?
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Re: Fender clone weird sound, motorboating ?
The amp seems to be oscillating, and inadequate power supply decoupling can cause that. So perhaps one or more of the new caps are faulty.
Did the amp work before you worked on it?
A 50 year old clone seems unusual. Is it a homemade / DIY build, or branded, professionally made?
Did the amp work before you worked on it?
A 50 year old clone seems unusual. Is it a homemade / DIY build, or branded, professionally made?
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Re: Fender clone weird sound, motorboating ?
It worked with tons of noise so i shut it down immediately.
Will a faulty cap paralleled with a working cap show the same symptoms ?
It was professionally made yes, 50 years ago by a guy named Farchi, fender and marshall amps were expensive due to taxes so he cloned them by request.
Will a faulty cap paralleled with a working cap show the same symptoms ?
It was professionally made yes, 50 years ago by a guy named Farchi, fender and marshall amps were expensive due to taxes so he cloned them by request.
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Stevem
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Re: Fender clone weird sound, motorboating ?
It’s not unheard of to have a bad new filter!
Start yanking out the preamp tubes starting with V1 and you should be able to narrow down what node of the power supply the motorboating is kicking off at.
Note that all BF and SF Fenders have a inherent problem in that there are up to 4 audio gain stages powered off of one filter node, and especially if back when that amp was built it was done so for higher gain then stock there should never be more then 2 gain stages powered off of any one filter node.
Start yanking out the preamp tubes starting with V1 and you should be able to narrow down what node of the power supply the motorboating is kicking off at.
Note that all BF and SF Fenders have a inherent problem in that there are up to 4 audio gain stages powered off of one filter node, and especially if back when that amp was built it was done so for higher gain then stock there should never be more then 2 gain stages powered off of any one filter node.
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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: Fender clone weird sound, motorboating ?
I did rewire it to have filter cap with a dropping spring for naother node.
After many hours of troubleshooting i found that one od the power tubes screen resistor went dead, replaced and all ia good now
After many hours of troubleshooting i found that one od the power tubes screen resistor went dead, replaced and all ia good now
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Stevem
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- Joined: Fri Jan 24, 2014 3:01 pm
- Location: 1/3rd the way out one of the arms of the Milkyway.
Re: Fender clone weird sound, motorboating ?
If it was a carbon comp resistor original to the amp I have seen the crack in half just due to the heat of sitting on top of the output tubes, and many times you can hardly make out that they are cracked!
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!