LSS Issue: No 5Watt, No Output & Solo, Small burning smell

[Unsu]

Hi guys, hopefully you can give a little advice or direction where my local amp tech can not (pains me to know they are supposedly an authorized Mesa Repair center)

So I brought my LSS in after it burned up on stage and shut down.

1. Amp tech replaced a power resister, a blown fuse and said one of the EL84's were defective.

2. I replaced the EL-84 with a matched new one.

3. Amp turns on now, but has microphonics, weird cracking, and solo/output knobs don't affect the signal, just the gain/master.

4. Amp tech decided two more of the tubes were defective.

5. I just replaced all of them with fresh EL-84's and new preamp tubes, and even switched between two recto tubes.

6. Amp is no different than before. Still the same scenario as always, even after moving tubes around and standby switching etc..

(Side note: also notice a weird lighting issue...green light comes on for channel 1/ft switch modes but turns off for channel 2. I dont remember if being like that, could be in my head though.
The burning smell is really minor, but still there, around the two power tubes closest to the recto tube. And when the fuse blew during my show it was a burning smell too)


I appreciate all the feedback others left on similar threads, but this scenario seems a little different and I have tried some possible solutions. I am sick of bringing my amp in for $50 repairs that involve the guy looking at the amp and deciding tubes are dead. He did that with my ENGL too and the problem ended up being the footswitch which he overlooked. And there is no other MESA techs in my area.

Mike

 

[plan-x]

That tech has got to go! Get another one! Forget about authorized, an amp is an amp.

 

[twally]

Yep,

Time for a new Tech-Mesa or otherwise.

 

[Jared Purdy]

Toss a new 5Y3 in there and see what happens.

 

[djw]

The light on the front panel is only on when Ch1 is active. It goes out when Ch2 is on. So that's working properly at least!

 

[Charles Reeder]

Hey: Sorry to read about your problems. One thing I can concur with...that's the advice you've gotten from others...get a new tech....fast! You might want to 'blow the whistle' on this dude to Mesa too. He's not doing either the company or customers any good at all!

In your list of problems...regarding number 3:
Part A.
"Amp turns on now, but has microphonics, wierd cracking"
This problem could actually be due to bad preamp tubes...in particular V1 and/or V2.
Part B.
"And solo/output knobs don't affect the signal, just the gain/master"
The first thing to check everytime you are confronted with this situation...is to check and make sure the little toggle switch on the back of the amp for the effects loop hasn't been accidentally nudged into the 'BYPASS' mode. If it has...then the effects circuit which powers the solo and output controls will be bypassed as well and the solo and output fesatures will not work. Make sure the effects loop is on! This should fix that! If it doesn't....you could have a bad effects loop pre-amp tube. If I remember correctly it is V3.

Best of luck:

Charles

 

[Unsu]

Hi guys thanks for the input! I actually forgot I had posted on here and almost gave up hope on the amp.

I brought it 100 miles to a trusted amp tech in Kitchener, Ontario and he fixed it up. Changed some resistors and retubed it once again.

It works! I guess the other tech simply didn't put enough time in it to test it after making his repairs.

Cheers
Mike

 

[AceBoogie]

my ace blew a power tube..then when i popped in a new, correct fuse, new mesa tubes, it smelled like burning and my amp wouldnt work with the loop in..level was at 50%, no volume with the loop engaged..turns out there was open resistors on the FX loop board..no idea why that would happen..my tech fixed her up and i dont use the loop anyways so its always on hard bypass..sounds like the same issue i had somewhat