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Avoustic 370 nasty noise

#21
dkelley said:
Just tossing this out there... you're probably looking at one or more of:
- dry capacitors needing replacement
- broken/intermittent connections
- potentiometers and switches needing significant internal cleaning and/or replacement
- Power supply (huge capacitors, diodes, transformer(s)) with issues due to sitting around...

so yea there's a lot to test. and testing and experience knowing what and how to test are the main thing to do at this stage... you could learn, but it's a lot of learning.... and time... and possible user error
Click to expand...
Possibly, but maybe not just as likely.
 
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#23
ardgedee said:
It could also possibly be excessive orgone saturation, leaky bias lubricant, muffler resonance or diode haze.
Click to expand...
I was thinking a defective framostat bearing which it relayed to the most blamed parts on earth… bad caps!
 
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#25
agedhorse said:
I was thinking a defective framostat bearing which it relayed to the most blamed parts on earth… bad caps!
Click to expand...
I totally forgot about those framostat bearings. If you don't clean them and apply a coat of the molybdenum grease on them from time to time, playing metal will surely wear them out and they will definitely tank on you!;)

(please, don't anyone take this comment seriously and try to find a framostat bearing)
 
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#27
Very funny. I am a tube amp tech but solid state isn't my cup of tea. The noise isn't like a bad capacitor. It's like extremely loud out of tune radio static.
This amp has huge can capacitors that show no signs of leakage. Indeed it has to go in to see an experienced solid state tech at this point.
Those of you that said visual inspection is such a small part of diagnosis are mistaken. I can trace the signal path but with an obviously damaged component I like to replace those first before proceeding
 
#28
Psyconoodler said:
Very funny. I am a tube amp tech but solid state isn't my cup of tea. The noise isn't like a bad capacitor. It's like extremely loud out of tune radio static.
This amp has huge can capacitors that show no signs of leakage. Indeed it has to go in to see an experienced solid state tech at this point.
Those of you that said visual inspection is such a small part of diagnosis are mistaken. I can trace the signal path but with an obviously damaged component I like to replace those first before proceeding
Click to expand...
I am not mistaken, visual is a very small part of the process and understanding how the circuits are supposed to work is a very important part of troubleshooting.

I have taught structured troubleshooting at the university and trade school level and it's a common misconception of those who are inexperienced which generally gets revised as the techs gain a proper education and become efficient and effective in their careers.

The more sophisticated the amp, the more important structured troubleshooting becomes.

You came here asking for help. If you already know how to repair equipment (by visually looking at it?), why are you asking us???
 
#29
johnk_10 said:
'nasty noise' is a vague description, so, for me, there's no way that i could diagnose your problem.
Click to expand...

Indeed it is vague. Funny though...I have (and love) a 370 that when being played in conjunction with a 402 cab - makes a "sort of" whooshing sound. Not terribly distracting, but there nonetheless. I've had it checked out on two separate occasions by different techs and they say it's simply......age.... :laugh:
 
#31
Psyconoodler said:
Very funny. I am a tube amp tech but solid state isn't my cup of tea. The noise isn't like a bad capacitor. It's like extremely loud out of tune radio static.
This amp has huge can capacitors that show no signs of leakage. Indeed it has to go in to see an experienced solid state tech at this point.
Those of you that said visual inspection is such a small part of diagnosis are mistaken. I can trace the signal path but with an obviously damaged component I like to replace those first before proceeding
Click to expand...

Do any of the controls have any effect on what you hear at all? That should at least let you narrow it down to what stage of the amp to be looking at.
 

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