LSS - tube(s) got fried?

[tiger roach]

After a big lightning storm, my LS Special wouldn't fire up. Sure enough, the fuse was toasted. After replacing the fuse, I find channel two aint working in 5w mode. Or 15w. In 30w mode it works. Turns out channel 1 only works in 30w also.

Does it sound like a power tube failure? I have a new set on order in hopes that is all it is.

Also will be getting a surge protector.

 

[ylo]

Usually problems originate with a tube, BUT, tubes are much more resistant to high voltage spikes than most semiconductor components. I have not seen the schematic for the LSS, but I suspect that you may have fried some transistors or logic chips used to control the output stage modes. Based on looking at Mesa's patents, the LSS probably uses some sort of simple logic to lift the cathode pins on the tubes that are not needed in the 15 W and 5 W modes.

Good luck. Hope it isn't too expensive.

PS: I always unplug expensive electronic equipment when not in use for protection against lightning surges. Surges can even jump power strips under worst-case conditions, i.e. near direct strike.

 

[rebob]

i had the same problem with out a lightning storm. the service guys were stumped. turned out to be the rectifier tube. this tube works for 5-15 watt modes but a diode runs the 30 watt mode. thats why it still plays in 30 watt mode. replace that baby and all should be fine.


good luck,

rebob.

 

[F.Ace]

After a big lightning storm, my LS Special wouldn't fire up. Sure enough, the fuse was toasted. After replacing the fuse, I find channel two aint working in 5w mode. Or 15w. In 30w mode it works. Turns out channel 1 only works in 30w also.

Does it sound like a power tube failure? I have a new set on order in hopes that is all it is.

Also will be getting a surge protector.

Damnit i got the same problem but no lightning storm for me,one mornign only the 30w mode was working...and the powertube dont seems to glow anymore.Anyway my dealer kept my amp in hostage since last week,its painfull.

 

[jbird]

i had the same problem with out a lightning storm. the service guys were stumped. turned out to be the rectifier tube. this tube works for 5-15 watt modes but a diode runs the 30 watt mode. thats why it still plays in 30 watt mode. replace that baby and all should be fine.


good luck,

rebob.

He said it!

 

[ylo]

Rectifier tube ! Yeah, sounds like this might do it.

 

[tiger roach]

i had the same problem with out a lightning storm. the service guys were stumped. turned out to be the rectifier tube. this tube works for 5-15 watt modes but a diode runs the 30 watt mode. thats why it still plays in 30 watt mode. replace that baby and all should be fine.


good luck,

rebob.

Cool, I'll try that! Totally makes sense.

*orders rectifier tube*

Thanks, I'll post back to this thread when I have some results to report.

 

[tiger roach]

Update:

The new rectifier tube is installed, and everything is working as it should again. 8)

Thanks Rebob & everyone else who responded.

This thread is an example of what I love about the 'net - I post with an obscure problem that could have had me frustrated for weeks, and within a half day someone with the exact solution needed has posted. God its a great time to be alive.

 

[rebob]

hi brian.

i actually know very little about tube amps. the LSS was my first in 20+
years. if it was any other problem, i would have been clueless.

i signed up to this board just because of your question, now i love it.
so thanks to you too.

did you notice any difference in tone?

take care, Bob.

 

[tiger roach]

did you notice any difference in tone?

I haven't played it enough yet to really make that call, but whatever difference there is is pretty subtle.

I am going to go ahead and change the power tubes to JJ's, and expect that change may be more noticeable.

 

[F.Ace]

I'm so frustrated,my amp is still in repair,the dealer told me that my power tube is broken (since april 27/06) i bought the amp on december 18/06,they didnt keep 5y3 tube in store(Italmelodie) and they told me that it can take 3-5 MONTHS before they get some....and they refuse to exchange my amp for another and told me a blah-blah-blah speach about Mesa putting the province of Quebec(where i'm from)at the end of their priority list.I've tried to order a 5y3 from the mesa site and each time an error happend,cant even e-mail then anything (error once again).This is so ridiculous and frustrating.I really regret my expensive purchase,I should have bought a 2 Marshall for the same price

 

[michael morguess]

Had the same thing happen to me last week. Rectifier fried, and only 30 watts setting worked. Mesa said they were sending me a new one (5Y3), haven't received it. bought the tube myself at local guitar shp. Put it in and all settings work.

However: now, whenever I switch between 30-15-5 settings, there is a "pop" sound. Never happened before. Any clues, anyone?[/b][/b]
Amp only three weeks old. straight out of the box.

 

[tiger roach]

I'm so frustrated,my amp is still in repair,the dealer told me that my power tube is broken (since april 27/06) i bought the amp on december 18/06,they didnt keep 5y3 tube in store(Italmelodie) and they told me that it can take 3-5 MONTHS before they get some....and they refuse to exchange my amp for another and told me a blah-blah-blah speach about Mesa putting the province of Quebec(where i'm from)at the end of their priority list.I've tried to order a 5y3 from the mesa site and each time an error happend,cant even e-mail then anything (error once again).This is so ridiculous and frustrating.I really regret my expensive purchase,I should have bought a 2 Marshall for the same price

I would just order a 5y3 from groove tubes and you'll have it in 3-4 days...

 

[tiger roach]

Had the same thing happen to me last week. Rectifier fried, and only 30 watts setting worked. Mesa said they were sending me a new one (5Y3), haven't received it. bought the tube myself at local guitar shp. Put it in and all settings work.

However: now, whenever I switch between 30-15-5 settings, there is a "pop" sound. Never happened before. Any clues, anyone?[/b][/b]
Amp only three weeks old. straight out of the box.

I haven't heard a pop when I change that setting, before or after the tube switch. However, it is the sort of setting that I set and leave alone, so maybe I just haven't noticed.

 

[robberns]

Same thing just happened to my LSS last night. Blew a fuse, then the 2nd channel would not work in 15/5 watt mode. Called Mesa today, they are sending a replacement tube. At least I can play in 30 watt mode until the tube arrives.
I'm planning on replacing the stock Mesa tube with a Bendix, which should last much longer.

 

[tiger roach]

Good grief! Maybe Mesa needs to find a new supplier for their 5y3's.

 

[robberns]

Well, I asked the Mesa rep why a tube would blow so quickly, and he said "They don't make them like they used to".
Apparently the Chinese version is not that stellar. Russian version is better, and NOS is best.

 

[michael morguess]

A little follow up on my previous post (rectifier fried, now a popping sound as i switch watts between 5-15-30):

I also notice that if channel 1 and 2 have different watt settings, there is a popping sound when i change channels, however, if both channels are on the same watt setting (no matter which one), there is no popping sound when changing channels. i have tried different outlets in my house, etc.

I installed a second new rectifier, still have prob; changed power tubes, still have problem. Just got off the phone with Mesa, and they suggested using a 5AR4 rectifier (a little tighter), and are sending me one. They said that they have had a hard time getting solid performance out of the last bunch of 5y3's. True or not? who knows.

Hey, Tiger Roach (Brian). Dig your Europe 72 icon.

 

[robberns]

That's interesting, because I asked the Mesa rep if I could substitute any other tube for the 5Y3 and he said no.
Curious to see how that other rectifier tube works for you.

 

[F.Ace]

Finaly got my amp since last week,i called back and yell at the boss...and convinced him to take the tube from another lonestar and wait for his order to replace it,he accepted.And no,i dont regret my purchase,my tone is so **** great.I just realize that when you dont use the drive switch on the ch 2 and set the gain lower you can colour your tone with much more eg without getting mud,try it with with the thicker voicing and set the gain to noon.I'm happy!