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Post by demiruyar on Jun 30, 2008 7:22:40 GMT -7
Greetings from Istanbul,Turkey Well to cut it short I bought this amp 2 days ago. 1.st day no problems at all.... 2. nd day: Check it out I was noodling around with my guitar and suddenly this noise started to appear and the amp did not amplify my guitars signal anymore.... What could be the problem? Thanks for looking.
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Post by kruzty on Jun 30, 2008 8:03:08 GMT -7
Maybe the phase inverter tube?
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Post by benttop (Steve) on Jun 30, 2008 8:15:47 GMT -7
I would agree that you need to do some tube checking. The vast majority of infant mortality issues in tube amps are related to tubes. It is unfortunate because there is nothing we can really do about tube reliability - in today's market you take what you can get.
Try swapping each preamp tube, one by one.
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Post by demiruyar on Jun 30, 2008 8:47:15 GMT -7
Interestingly,the amp is working perfectly again...It all happened when I was playing and the problem went away after after I switched on/off the amp several times.So I'm a bit scared that the same thing would happen to me on stage.I think I will have to change the tubes
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Post by benttop (Steve) on Jun 30, 2008 9:07:09 GMT -7
Oh that's worse. It's terribly hard to troubleshoot a problem that goes away. But now I'm wondering if you might have a tube socket that may be loose. Or a loose reverb cable can cause a similar sound. If you get the sound again, before shutting off the amp, turn your reverb control to see if it affects it. It will also be useful to know if your master volume affects it.
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Post by demiruyar on Jun 30, 2008 9:16:40 GMT -7
The master volume has no affect on the strange sound.On the video above I messed with master and normal volume..Also the reverb was off(counter clockwise).The only thing that cought my attention is that the reverb is catching alot of radio frequencies,fm signals to be precise.The more I turn the reverb counter clockwise the more it picks up fm signals.But I dont know if that has an particular effect.And thank you very much for the suggestions Benttop.You guys are very lucky to live in the States.Well its not that easy to ship a amp to get repaired from Turkey to USA
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Post by benttop (Steve) on Jun 30, 2008 10:16:13 GMT -7
Well if Master doesn't affect it, and reverb was off, that means the sound was either coming from a power supply problem or a tube problem past the master, such as the PI, or output tubes. I've never heard an output tube issue cause such a sound, but that's no indicator of much. Since the problem went away I'm thinking it could be something mechanical, like poor contact on a tube pin, or maybe even a bad solder joint, but solder seems far fetched (I've seen how they do QA on these and I doubt the Doc has had too many solder related issues).
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