Hi to all:
I've had my Lonestar Special for a little less than six months, and took it in the shop several days ago.
After powering it on, I plugged a guitar into it at low volume, and after giving me about 3 or 4 seconds of clean sound I heard a "pop", then saw some smoke come out the back, and the amp went silent but did not blow the fuse, and the power light was still on.
I shut the power off, looked at the tubes and couldn't see a thing, but smelled
like a burnt component.
After taking the power tubes out, I plugged in the one for the 5 watt setting, turned the 5 watt setting on and the amp sounded great. Then I plugged in the tube at the opposite end and tried the 15 watt setting, it sounded great as well. After plugging in the other two power tubes, the 5y3 rectifier tube turned blue and the fuse blew.
I then took it to the repair station. The tech checked out the amp and said that it was a bad power tube and of course a bad 5y3 rectifier. A Mesa tech (after I called them and explained the symptoms) said that a power tube had shorted and took out a screen grid resistor.
The techs at the repair shop that do warranty work for Mesa said that the screen grid resistors check out fine, did not exhibit any symptoms of being burnt, so insisted that the tubes were all that were wrong with the amp.
I'm picking it up tomorrow, and would like opinions on this.
I am an electronic tech as well, and would love to get my hands on a schematic to check these screen grid resistors myself.
I'm looking for opinions on that amp repair and any ideas as to where the smoke could have possibly come from. Could a shorted tube "smoke" after shorting? Could it be that the vacuum was destroyed and smoke came from inside the tube?
Thanks,
Art
I've had my Lonestar Special for a little less than six months, and took it in the shop several days ago.
After powering it on, I plugged a guitar into it at low volume, and after giving me about 3 or 4 seconds of clean sound I heard a "pop", then saw some smoke come out the back, and the amp went silent but did not blow the fuse, and the power light was still on.
I shut the power off, looked at the tubes and couldn't see a thing, but smelled
like a burnt component.
After taking the power tubes out, I plugged in the one for the 5 watt setting, turned the 5 watt setting on and the amp sounded great. Then I plugged in the tube at the opposite end and tried the 15 watt setting, it sounded great as well. After plugging in the other two power tubes, the 5y3 rectifier tube turned blue and the fuse blew.
I then took it to the repair station. The tech checked out the amp and said that it was a bad power tube and of course a bad 5y3 rectifier. A Mesa tech (after I called them and explained the symptoms) said that a power tube had shorted and took out a screen grid resistor.
The techs at the repair shop that do warranty work for Mesa said that the screen grid resistors check out fine, did not exhibit any symptoms of being burnt, so insisted that the tubes were all that were wrong with the amp.
I'm picking it up tomorrow, and would like opinions on this.
I am an electronic tech as well, and would love to get my hands on a schematic to check these screen grid resistors myself.
I'm looking for opinions on that amp repair and any ideas as to where the smoke could have possibly come from. Could a shorted tube "smoke" after shorting? Could it be that the vacuum was destroyed and smoke came from inside the tube?
Thanks,
Art