Problem with my LSS

[axman53]

My LSS recently started misbehaving: sound cuts in and out, sometimes completely out but sometimes it just becomes faint and fuzzy sounding, then cuts either all the way out or all the way back in. When this happens, it happens to BOTH channels, and switching the effects loop to hard bypass the amp also bypasses the problem. In other words, with the problem happening, I can switch the loop in and out and go from normal (loop bypass) to the sound cutting out again when I switch the loop back in. Ideas on where to start with this? There's a fresh set of tubes in there a couple of months ago from EuroTubes. Of course the problem is intermittent, which just about guarantees that if I bring it to an amp shop it will work fine, but when I gig it will act up . Thanks for any pointers.

 

[djw]

Sounds like you have a bad preamp tube in V3 or maybe one of the jacks needs some contact cleaner.

 

[handyandy]

I agree... Check out this topic;

http://forum.grailtone.com/viewtopic.php?f=4&t=25102&start=15

 

[moonroom]

Hey all- new to the board but just wanted to confirm that I ran into the exact same problem w/the V3 tube in my LSS. This was while I was still trying it out at GC a couple of weeks ago.

With the loop enabled and nothing running in it I got the intermittent volume cut-out. Strangely enough, once I got the amp home I found that putting an effect into the loop appeared to solve the problem. I still swapped out the V3 tube with an older mesa SPAX7 just to be safe; haven't had the problem since.

Also, I'd be remiss if I didn't give a big shout-out to everyone on this board. I must have read almost every single post in the Lone Star section while I was deciding whether or not to pony up and take the plunge. Now that I have, I've gone from cautiously optimistic, to pleasantly surprised to 'you gotta be f**kin' kidding me!' Love this amp!

 

[bigpine]

I had a problem like yours with my LSS. The rectifier tube was loose. I have not had any problems since. I make shure to check it every week.

 

[axman53]

OK, so I tried the easy stuff first: V3 (the cathode follower tube). That was not my problem, however I did find that the MESA tube that came in this spot with the amp was indeed marked Chinese, so MESA was practicing what they preach by the time they shipped this amp. I also tried the 5Y3, although I know the amp will work fine even without this tube as long as you're not on the 15W setting. Again, no fix. So I had no choice but to open her up, which I did.

With the chassis out and power & speaker connected, I powered her up. Initially, no problem. Then I flexed the chassis and I got the same symptoms I have been experiencing. I used a plastic pen to tap around. When I tapped around the effects loops send/return jacks, boom, sound cut out. It appears that these jacks need some contact cleaner so that when I don't have my board plugged into them they make a decent bypass connection. This explains why switching the loop out fixed the problem and also why the problem was happening on both channels. Funny thing, I almost never play the amp without my board plugged in, and the problem never appeared as long as the send/return jacks had the plugs from my board inserted. I'll have to bring some contact cleaner home from my office and see if that takes care of it. Will update once I've done that. Thanks for your suggestions.

 

[djw]

Seems to be a fairly common problem, thankfully easily fixed. Glad it looks optimistic for you, axman53.

Also, welcome to the Lonestar Nation, moonroom!

 

[axman53]

I'll have to bring some contact cleaner home from my office and see if that takes care of it. Will update once I've done that. Thanks for your suggestions.

Yes, it was definitely the contacts on the send/return jacks. A little contact cleaner fixed her up just fine. Just wanted to close out this post with a definite fix. Cheers!