2. amps-preamps
  3. 1132847783

Help troubleshooting amp

Hi,
When I turned the system on this morning in anticipation of a long holdiay of music there was no signal in my right channel. I first checked all connections which were fine and then I subbed in a pair of replacement tubes for the right side of my preamp, still only on channel. I then switched my attention to my amp, I switched both pairs of 6550's from left to right. Now no signal in either channel! This leads me to beleive that the trouble rests with the amp. I'm going to try switching 6550's back again but one at a time to see if I at least get the left channel back. Regardless I'm pretty sure it's a tube issue but if anyone else has any ideas I'm listening. Why do these things only happen on weekends and holidays?
128x128jond

Showing 4 responses by jea48

jea48
4,321 posts
 
>>"I switched both pairs of 6550's from left to right. Now no signal in either channel!"<<
>>"This leads me to beleive that the trouble rests with the amp."<<
>>>>>>>>>>

Just a guess, a bad shorted 6550 tube. The bad tube may have damaged something in the right channel. Installing the bad tube in the left channel may have caused damage there as well.

Post a thread on Audio Asylum on their tube forum and ask your question.
http://www.audioasylum.com/audio/tubes/bbs.html
jea48
4,321 posts
 
>>"I should be able to get my hands on a replacement quad of tubes today and if those don't work it's time for repairs. Wish me luck!"<<
Jond

Jond, imho if I were you I would take the amp to the repair shop first. Without knowing for sure what is wrong with the amp you might cause damage to the new 6550 tubes. The repair shop will test all the tubes including the two 9 pin small tubes.
http://cgim.audiogon.com/i/vs/i/f/1128880649.jpg
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jea48
4,321 posts
 
Jond, if I understand you correctly you are going to take the amp and old tubes with you to the repair shop. They will be able to test the old tubes while you are there. Does the Amp have auto output tube bias adjustment for the power tubes, or do you set the bias mVDC voltage manually for the amp? If the bias mVDC voltage is way off you could damage any new tubes you would install in the the Amp. I still believe something is damaged in the Amp due to a shorted 6550 power tube...
jea48
4,321 posts
 
Jond, sounds great. $180.00 thats not bad... Thanks for letting us know what the problem ended up being. I wish more members would follow through on their threads like you did.

Jim
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