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Post by alloftheabove on May 4, 2008 19:50:27 GMT -7
Hi all. I hope this is the right forum for this question. The other day I tried to fire up my Mazerati and found that there was no sound at all coming from the amp. The power light comes on, the power and preamp tubes glow, the fuses are good, but there is no sound. There's not even a buzz or hum from touching the end of the cable. I tried a couple different cables with no success. Any suggestions?
FYI - this is the older Mazerati head through a 1x12 cab. It has worked perfectly in the past, and even worked a few weeks before I tried to use it again. Also, I recently moved, but the Z rode with me in the car so as not to get joggled around too much. It worked after the move, so I don't think the move caused this issue.
Any ideas on what might be wrong? Thanks in advance!
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Post by benttop (Steve) on May 4, 2008 20:25:59 GMT -7
Be suspicious of something mechanical - broken speaker cord, broken wire in the speaker cab, broken plug - make a thorough check of every inch of everything from the speaker terminals to the amp output jack. And while you have this condition, do NOT turn the volume up to full and play your guitar into the amp - if there is an open circuit you could damage your amp. Find out what's interrupting the signal.
If none of that is productive, make sure of the fuses by using a multimeter to check them. They aren't usually obviously blown, even when they have opened. If they are ok, start thinking about your rectifier tube. If you don't have a spare, get one and try that.
By this point you should have discovered the problem, and I'm betting it will be mechanical, but it could be electrical. If you haven't found it by this point, come back and fill us in to let us know what you find.
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Post by alloftheabove on May 6, 2008 19:07:05 GMT -7
Thanks for the advice - will do! Robert
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Post by Strato on May 7, 2008 20:26:18 GMT -7
Be suspicious of something mechanical - broken speaker cord, broken wire in the speaker cab, broken plug - make a thorough check of every inch of everything from the speaker terminals to the amp output jack. And while you have this condition, do NOT turn the volume up to full and play your guitar into the amp - if there is an open circuit you could damage your amp. Find out what's interrupting the signal. If none of that is productive, make sure of the fuses by using a multimeter to check them. They aren't usually obviously blown, even when they have opened. If they are ok, start thinking about your rectifier tube. If you don't have a spare, get one and try that. By this point you should have discovered the problem, and I'm betting it will be mechanical, but it could be electrical. If you haven't found it by this point, come back and fill us in to let us know what you find. Ditto this. I had the same problem with my Maz 18. I looked at the fuses, and they looked ok. But as it turns out, the slo blo fuse went.
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Post by alloftheabove on May 26, 2008 19:19:16 GMT -7
Okay, so I've checked the cables - they're fine. The connections to the speaker are fine. I changed the fuses with no luck. I guess I'm on to the rectifier tube next.
Just to be clear, I have NO sound at all - no white noise, no hum, nothing.
Also, it is possible one of the kids in my extended family may have turned the amp on while it was not attached to the speaker cab. Would this cause any issues?
Thanks again for the help folks...
Robert
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Post by benttop (Steve) on May 27, 2008 5:43:56 GMT -7
Okay, so I've checked the cables - they're fine. The connections to the speaker are fine. I changed the fuses with no luck. I guess I'm on to the rectifier tube next. Just to be clear, I have NO sound at all - no white noise, no hum, nothing. Also, it is possible one of the kids in my extended family may have turned the amp on while it was not attached to the speaker cab. Would this cause any issues? Thanks again for the help folks... Robert If the Rectifier is dead you won't have any sound because the power supply is off. Try the rectifier and let us know if that solved it. As far as your other question, you never want your amp on with no speaker plugged in. But if there was no audio present, it is not likely that you have a problem as a result. Phil tells the story of his Ghia being on for a week with no speaker plugged in to it, and it was fine. But if audio is present, you can take out your output transformer pretty quickly if there is no load.
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Post by bluzman on May 27, 2008 7:24:52 GMT -7
If you have a send/return loop in the back plug a cord into that loop. There are contacts that sometimes oxidize from lack of use on those.
After trying that and the above ideas and it still isn't working, it time for a tech.
Good Luck!
PT
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Post by alloftheabove on May 27, 2008 18:47:50 GMT -7
Thanks again for the help folks - I'll check the loop and then try the rectifier.
Robert
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Post by alloftheabove on Jun 5, 2008 19:01:22 GMT -7
I just wanted to let everyone know that I changed the rectifier and that was problem. So I'm back in business! Thanks again to all for the advice.
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Post by myles on Jun 23, 2008 9:12:25 GMT -7
Remember this simple rule ....
If the power light is on and no sound comes from the amp 90% of the time it is a bad tube rectifier if the amp uses a tube rectifier.
Second ... always carry a spare rectifier.
Third .... all current production rectifiers available today have reliability issues and rarely meet design spec. NOS rectifers are available and will last for decades and are a sound investment.
Side note ... in the case of 5Y3 equipped Carmen Ghias, most of these are delivered with NOS USA rectifiers.
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