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Twin Reverb Problem!!


 
8/20/1999 1:13 PM
Jay
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Twin Reverb Problem!!
Well, I'm taking to my tech on Monday but i'd like to have an idea with what could have gone wrong ahead of time. Here's the scenario. I was playing at practice last night with the volume to only about 3. All of a sudden it started making a high pitched feedback "like" type squeal. I pulled out all of my guitar cords and pedals and turned the volume down. It stills makes the squeal, but if i tap the top of the cabinet it stops and sounds normal. Tap again and it squeals. Obviously it something loose inside. Any clues to what it could be?  
 
 
 
Thanks!  
 
Jay
 
8/20/1999 1:28 PM
R.G.
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quote:
"Any clues to what it could be? "
 
 
Its probably a resistor, capacitor, wire, tube or socket contact  
 
 
 
;-)
 
8/20/1999 2:28 PM
Jay
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quote:
"Its probably a resistor, capacitor, wire, tube or socket contact"
 
 
 
 
All right there wise guy! :)  
 
 
8/20/1999 3:04 PM
R.G.
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Sorry - I couldn't resist.  
 
 
 
Anything that is subject to mechanical vibration like that is a loose contact somewhere - but you already knew that. It could be a lot of things, unfortunately. The real way to debug this is to get it running, get it to do the deed, then poke around gently with a wooden stick until you can reliably make it start and stop by poking. Some things are diagnosable by simple description, but this isn't one of those.
 
8/20/1999 4:22 PM
J Fletcher
A bad tube would be my 1st guess. Try this. Looking at the back of the amp, with the amp on standby, pull out the 1st tube on the right. Turn the amp on. Does it feedback? If yes, then put the amp on standby, and pull out the 2nd tube from the right. Turn the amp on. Feedback? If yes, just continue pulling tubes in this manner. If no, replace that bad tube with a known good one. If it feedsback now, then it's probably not a tube problem...Jerry
 
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