Laney tube amp problem - what to do?

[Ondoval]

(This is about a guitar amp, but I dont know where else ask, so please forgive me)

I have a Laney GH100L 100watt tube amp. Some weeks ago it failed at a rehersal session. It made a roaring hum/buzz. Very loud. Was not playable. No other sound came through.

I took the amp home and tested it on a different cabinet the next day. Different speaker cable, different cables etc. I took about 30min on living room volume and then the roar of doom came back. The loud noise was unaffected by master volume, gain and even continued after I unplugged the guitar.

Fast forward to today, several weeks later. I made arrangements with a tech today, as I now have money for repairs, but wanted to check there was still an issue. Played the thing semi loud for almost 2 hours and nothing. Plays perfectly. Called the tech and he said he didnt want me to take it in as he would possible spend hours without finding the problem.

This sort of sucks. I dont want to rely on this thing on rehersals now, as I promise you it will fail the moment we start playing. I could buy a new/backup amp, but then I wont have the money to repair the Laney.

Here's a link to a video I took when I could recreate the issue on day 2:

What to do? Any insight from you awesome people on talkbass (and guitar)?

 

[bass player 53]

Difficult to diagnose on-line, but…
I had sort of a similar issue with my vintage ‘69 Deluxe Reverb. It was an intermittent problem. The 6V6 power tubes would red plate one day, not the next. It turned out to be a bad solder connection from the power transformer to the resistor and diode along the bias path. I’m skilled in electronics and found it myself. If you don’t have this training, take it to a tech.

 

[Slevage]

The good news- the problem is repeatable making it easy to troubleshoot.
The bad news- you can’t fix it yourself and it would be dangerous to attempt a repair.
Find a competent repair shop that is familiar with tube amplifiers AND can get parts. Preferably an authorized Laney repair shop.

 

[agedhorse]

I’m afraid this is the sort of issue that’s going to require a tech to sort out. It COULD be something as simple as an intermittent tube, but this is really just a wild ass guess at this point.

Your tech is correct, intermittent problems can be time consuming to diagnose.

 

[agedhorse]

The good news- the problem is repeatable making it easy to troubleshoot.
The bad news- you can’t fix it yourself and it would be dangerous to attempt a repair.
Find a competent repair shop that is familiar with tube amplifiers AND can get parts. Preferably an authorized Laney repair shop.

It appeared repeatable until it wasn’t. That makes it more difficult and time consuming to troubleshoot

 

[Slevage]

It appeared repeatable until it wasn’t. That makes it more difficult and time consuming to troubleshoot

My local guy is reasonable to deal with.
He’d start with a minimal bench fee and keep the amp running with music playing through it while other work takes place. I wouldn’t want the OP to dive in and start changing parts.

 

[KevInDaBassment]

...Called the tech and he said he didnt want me to take it in as he would possible spend hours without finding the problem...

Not to be a jerk, but with that attitude I'd look for someone else to service the amp. If the brakes on your car intermittently fail, would you take it to a mechanic who rejects it because it will take a while to figure out?

Giving the benefit of the doubt, the tech may be trying to save you money, saying the bench fees will get out of hand and he wouldn't be able to find the root cause. IMO, that's the point of taking it to a professional...they can troubleshoot and uncover something that isn't dead obvious. IDK, might want a second opinion on that repair...

 

[eniac]

Called the tech and he said he didnt want me to take it in as he would possible spend hours without finding the problem.

I'd take it in anyway and have him pull the chassis and check for anything in there that's come loose or unsoldered. Shouldn't take more than an hour, including chassis pull & reinstallation. 2 hours if he checks side B of the preamp board as well for bum solder joints.

 

[Sparky Mark]

As it stands, you have no confidence in the amp, so it's not usable and worthless. I agree with eniac in as far as you could find a good tech and pay for a health check on the basis that no fault may be found, but you'll pay up to an agreed amount for parts/labour. A good tech may find the problem relatively quickly; alternatively you could just keep playing it at home until the fault becomes permanent and hopefully neither terminal for you or it.

 

[logdrum]

I think you need to wait a bit for the tubes to heat up. Is this how you start up the amp? When this get's repaired, I suggest waiting 20 seconds before switching standby to play mode

 

[Wasnex]

I can be very difficult to trouble shoot intermittent problems. So I can understand the tech's reluctance. He could poke around, but there is no guarantee that it will be possible to determine the cause if the problem does not present. Unfortunately there are many possibilities. Hopefully the problem eventually become continuous...or at least occurs consistently/predictably.

Some techs may be willing to let the amp cook on their bench while they work on other amps. Not much can be done if it doesn't act up.

Standard practice is to charge a non-refundable bench fee.

Sorry I don't have better news for you.

 

[Ondoval]

Thank you, everyone who chimed in here! I will do as suggested and find another tech to get a second opinion.

PS: Some asked about starting the amp. I usually push the power button, wait for like 30 seconds, then push standby. However, when I made the video above the amp had been played for more than an hour and then started to go crazy, so it was already warm.

 

[dbase]

Sell it and buy a Mesa, problem solved, end of story.

 

[bass player 53]

Sell it and buy a Mesa, problem solved, end of story.

Do you suggest selling it broken or fixed? Telling a potential buyer it has issues or not telling? End of story?

 

[agedhorse]

Do you suggest selling it broken or fixed? Telling a potential buyer it has issues or not telling? End of story?

Here's the problem... if it's fixed there's no need to sell it, if it's not fixed then the right thing to do is disclose what's known (and what's not known) about the issue.

 

[bass player 53]

Here's the problem... if it's fixed there's no need to sell it, if it's not fixed then the right thing to do is disclose what's known (and what's not known) about the issue.

Yes, of course. The poster’s use of the emoji is rather open to interpretation; joke, hidden meaning, flirtation, etc. I think they were joking, in which case I was joking too.
If they were suggesting something shady via hidden meaning, then the problem is not “solved” and there’s no
“end of story.” Either way, I totally agree with you, Mr. agedhorse.

 

[agedhorse]

Yes, of course. The poster’s use of the emoji is rather open to interpretation; joke, hidden meaning, flirtation, etc. I think they were joking, in which case I was joking too.
If they were suggesting something shady via hidden meaning, then the problem is not “solved” and there’s no
“end of story.” Either way, I totally agree with you, Mr. agedhorse.

I just finished the repair of an amp that had serious hidden problems (aside from not working correctly)... to the tune of over $600 which essentially resulted in a rebuild equal to a new amp. While the deal appeared good on the surface, what wasn't disclosed was the kicker.

Fortunately I still stock all of the parts (including all replacement PCBs) for this model, otherwise it might not have been repairable. It was that bad. It's worth about $700 in that condition (but at least he has a service warranty now).

 

[bass player 53]

I just finished the repair of an amp that had serious hidden problems (aside from not working correctly)... to the tune of over $600 which essentially resulted in a rebuild equal to a new amp. While the deal appeared good on the surface, what wasn't disclosed was the kicker.

Fortunately I still stock all of the parts (including all replacement PCBs) for this model, otherwise it might not have been repairable. It was that bad. It's worth about $700 in that condition (but at least he has a service warranty now).

Yeah, as a consumer of a lot of used gear over the years, I can say that there’s a lot of “what wasn’t disclosed.”
It’s great that you were able to salvage that thing; sounds like a win.
I don’t think I’m overstating that you’re a great service to many here on TB, and the bass community at large. Your technical expertise and integrity are not overlooked.

 

[Ondoval]

Update: I found a different tech 30min away willing to take a look at it. Older guy working out of a super messy Oslo apartment. Luckily the beast showed itself the minute he hocked the amp up. Within seconds he confirmed it was a bad power tube. He showed me how the tube would start to glow like crazy.

So glad I took the advice of finding a different tech! I really like this amp.

Thanks for all the advice and moral support!

 

[Ondoval]

Sell it and buy a Mesa, problem solved, end of story.

I'd have to sell a dozen of the Laneys to afford a Mesa