Lonestar Special blows fuses

[jyant]

I've had a Mesa Boogie Lonestar Special for a little over a year. Two nights ago when I got through playing I put the amp on standby, unplugged the guitar cable and footswitch cable. The phone rang and I forgot to come back and turn off the power switch. This morning I sat down to play again and the amp would not power up (the power switch was on and the standby switch was on as I had left them, but the amp was dead). I checked and found a blown fuse so I replaced it and the amp immediately blew it. All I got was a very brief (one second) hum out of the cooling fan before the fuse blew. The pilot light didn't as much as flicker. I tried a new 5Y3 rectifier tube but that didn't solve the problem.
Does anyone have any ideas on what might be the problem here?
Thanks ahead for any input!

[stokes]

The Lonestar is known for eating current production 5Y3's.Mesa will actually send you a free one when the one you have cooksand 9 times out of ten the "new' one will go again.I have found a NOS 5y3 will hold up better,and a 5V4 is even better.The only problem with the more dependable 5V4,or NOS 5Y3 is that if Mesa finds out you use one,they will void your warranty.The solution to that is,dont tell them.If for any reason you have to send it back for warranty work,just make sure you put the crap tube they sell back in.Of course it is possible that something else could be wrong,but that rectifier is the most common problem with that amp.

[Mars Amp Repair]

Also have had some shorted power rect diodes (DR1-DR) in them, too. g

[stokes]

Originally Posted by Mars Amp Repair

Also have had some shorted power rect diodes (DR1-DR) in them, too. g

I havent run into that issue in the Lonestar,but they do run that 5Y3 close to the edge and the current production 5Y3's just cant cut it.They are aware of the problem,that is why they will send you a new one for free.Guess they purchased too many of these inadequate tubes and once their stock gets depleted they will offer a real fix,such as the 5V4 which should run forever in that amp.

[Prairie Dawg]

Originally Posted by stokes

I havent run into that issue in the Lonestar,but they do run that 5Y3 close to the edge and the current production 5Y3's just cant cut it.They are aware of the problem,that is why they will send you a new one for free.Guess they purchased too many of these inadequate tubes and once their stock gets depleted they will offer a real fix,such as the 5V4 which should run forever in that amp.

I would probably use a 5R4 myself, or a 6087. That way you keep the B+ about the same but you have a lot more durable tube with the same filament current draw. Of course you need a little extra room, but if you have it the 5R4 is good. The 6087 is a military remote heated 5Y3 and it's the same size. It's relatively bulletproof, and I ran one in my AC30 for a while with no problems.

The only comparison you can make between today's so called "5Y3" and the older domestically made stuff is that the filament voltage and pinout is the same-after that all bets are off.

[jyant]

Thanks for the input guys. I've tried two 5Y3 rectifier tubes that are known to be good...the amp still blows fuses. I'm going to take it to a Mesa service center and hopefully it will be covered by the warranty.
By the way, a few months ago the amp did blow a Mesa 5Y3 rectifier tube, which I replaced with another Mesa. I'm gonna look for a 5R4 or 6087.
Thanks for the input.

[musicmahon]

My Mesa Lonestar Special fuse also blew, i replaced the fuse and thankfully it did power up again but it wouldn't make any sound on the 5 watt setting or the 15 watt setting. Why does it work on the 30 watt setting and what do think the problem is/which tube(s) are the problem? many thanks