What is wrong with my amp?

[jonnymangia]

I have a Laney LC15, 15w tube amp that I recently bought used.
For the first week or two that I had it, no problems.
Then, tonight something strange started happening. I'm playing for about 10-15 mins, when the amp's sound starts to fade out, then completely disappears. After about 5 minutes, the sound will start to come back again. Then, after another 5 mins if playing, the same thing happens. ade out sound, nothing, then a gradual return. This has been happening all night. The power is still on, the cables look fine. I am plugging directly into the amp.

Do you think this is something tube related? Should I just send it back to the guy?

HELP!!!!

 

[wixedmords]

Re: What is wrong with my amp?

It can be the tubes, no doubt. How's the heat JM (Feel the chassis face by the knobs)? Those can run hot.

I always change tubes in used amps. They are a wear item.

 

[jonnymangia]

Re: What is wrong with my amp?

It can be the tubes, no doubt. How's the heat JM (Feel the chassis face by the knobs)? Those can run hot.

I always change tubes in used amps. They are a wear item.

Good to hear from you my man, I know you are the resident Laney expert around here. I didn't feel the chasis face when it was on, but I did run my hands near the open back and the tubes were definitely hot. WHy would the tubes make it cut out like that...and thengo back on again?

 

[jonnymangia]

Re: What is wrong with my amp?

UPDATE....

Just started playing again and the sound faded out after less than 5 mins. And the front chassis is NOT hot.

 

[kmcguitars]

Re: What is wrong with my amp?

When the sound fades out are the tubes still lighting up? If so, Next time it fades out try plugging into the FX loop return. Doing this by-passes the preamp. If it works thru the FX loop? this means the problem is some where from the input up to the FX loop. At any rate I'd send it back.

 

[wixedmords]

Re: What is wrong with my amp?

Well JM, There are many others that tower over me here. I am just a humble dood.

The tubes in most tube amps will be hot, but EL84 amps run even hotter.

I am glad the front of your chassis isn't overly hot to the touch.

Anyway, I think you said that was the LC15R, not the LC15. I believe you have an effects loop. You can try cleaning the effects loop jacks with electronic contact cleaner you can buy at Radio Shack. This is usually spray that you spray into the jacks and plug a cable into the jack a few times to clean the jack. Sometimes you can test this just by plugging in a cable to both effects loops jacks, jumping the jack.

If cleaning the loop doesn't do it, I would pick up a new matched set of EL84's for that amp. Removing the tubes in this amp is made so much easier by turning it over so you can see the tube sockets better. Tubes would be about $25.00, shipping included.

 

[wixedmords]

Re: What is wrong with my amp?

KMC beat me to the "effects loop" punch.

AS KMC said, you always have the option of sending it back.

EDIT: Just saw your other thread. Sounds like you may have an out.

 

[jonnymangia]

Re: What is wrong with my amp?

It's an LC15, not the LC15R so there isn't an effect loop.
I'm going to try sending it back to the guy. I should be protected since it was an Ebay/PayPal purchase.

In the event that I get screwed and can't get my money back, do you think my first line of attack should be to replace the tubes? Again, it's the LC15, so I can't play with the effects loop as you guys recommended.

BTW - I'm sure this doesn't matter, but I had a new bridge pickup installed today. At first I thought that may have been the cause, but then I started playing solely through the neck pup and the same thing happened. I just figured I'd mention that.

J

 

[wixedmords]

Re: What is wrong with my amp?

It's an LC15, not the LC15R so there isn't an effect loop.
I'm going to try sending it back to the guy. I should be protected since it was an Ebay/PayPal purchase.

In the event that I get screwed and can't get my money back, do you think my first line of attack should be to replace the tubes? Again, it's the LC15, so I can't play with the effects loop as you guys recommended.

BTW - I'm sure this doesn't matter, but I had a new bridge pickup installed today. At first I thought that may have been the cause, but then I started playing solely through the neck pup and the same thing happened. I just figured I'd mention that.

J

When troubleshooting, you want to test each item in the signal chain with known good items. You may want to take your guitar and cable to another amp and try it out. They are likely not the issue, but it never hurts to test them.

I would do the tubes next if it were me.

Good luck.

 

[greendy123]

Re: What is wrong with my amp?

Well just trying the cleaning all jacks contact spray thing first, if that doesn't work and you decide to keep the amp get it checked out by an amp tech. It might be bad solder points or bad cables.

 

[jonnymangia]

Re: What is wrong with my amp?

ANOTHER UPDATE ...

Amp just crapped out again. Tubes remained lit when amp was "mute".
It's definitely not the pups, as I played from both the neck and bridge and the amp cut out in both settings.

I'm going to try a new cable tomorrow and if the amp is still cutting out I think I have enough evidence to point to a defective Laney.

 

[AmirH]

Re: What is wrong with my amp?

Sounds similar to having a cable crap out. I hope it's just that. Good luck.

 

[suislidE03]

Re: What is wrong with my amp?

Looking back on the problems i had with my Laney, i seriously doubt its something simple. Mine had a goofed chip inside the amp somewhere, took them a while to figure that out. Cost me $140, but again, they had to do a number of other things before they found the problem. I would say it cost around $50 just for the chip replacement. Running flawlessly since that, so im happy with it. I would send it back to the guy and let him deal with it first. If you cant, you can try new tubes but i still have my doubts. Remember, i had these exact same volume drops with my Laney. Take it to the tech with what i told you and see what they can do.