I have a Lonestar Classic and am experiencing total power failure. It is blowing fuses immediately powering up WITH all power tubes removed (pre-amp still in place) and in standby mode. This came out of nowhere. I was fine tuning some tones last night, all was well, put it in Tweed mode for a minute then put it back, as I was comparing overall tone. I generally prefer standard mode. I then shut it down. About a half hour later I turned it back on and poof, I blew a fuse. Tried another and poof. Then removed all tubes to verify it wasn't a tube. Same thing. I'm reading that it's almost certainly the power transformer, although various folks say they've never seen a MB with a bad transformer. I had recently replaced all four screen resistors, as one blew out. The amp has been working fine, but could this be related? The big question of course is if it is the power transformer why did it go out? I wasn't prepared for something like this to happen, total bummer. I have no repair facility nearby, so this is likely to involve shipping if I can't fix it myself, which is I prefer to do. Thanks for help or suggestions to move forward on this.
Help with Lonestar Power Failure Troubleshooting
- Thread starter Bill
- Start date
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plan-x
Well-known member
Check those screen resistors again.
They are fine, all ohm out at 514. With no tubes and on standby a bad screen resistor wouldn't cause the amp to blow the fuse. Wish it was something so simple. I'm probably going to have to pack it up and send it to MB. Not many choices.
It appears that the problem boils down to the MOV (metal oxide varistor). It blew. It's an easy change and costs about 2 bucks. I got help from the Hoffman amps forum. It's a great forum. Here's a link.
http://el34world.com/Forum/index.php
http://el34world.com/Forum/index.php
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