What do you do when a customer brings you an amp with an intermittant problem...

[jcollins]

And it works fine once it's in your shop? I've got a little marshall SS amp in my shop right now that the customer swears up and down has problems with the input jack causing volume fluctuations. And with different cords and guitars.
He says that wiggling the jack can fix the problem.

I can't make it fail. I've talked to the customer and told him my findings. We agreed that I would replace the jack anyway.

My deal with the store I work for gives me a minimum bench charge of $45. The store adds $15.

So say I replace the jack and he reports the problem still exists?

What would you do? Take it back, charge him another $45 and fix replace something else. Tell him it's not worth anymore money? Refund his $?

In general what do you do when you can't reproduce the reported problem?

[Amp Kat]

I power it up and let it sit with an ax plugged up and ready to play and start working on another amp. Every hour or so go and play it and see if it acts up. Sometimes it's just a matter of it heating up enough but also have his cables checked and maybe his setup in case it's something other than the amp. Try beating the top with your fist and give it a good wack. It could be a loose cap or ground that comes loose when vibrated a certain way. I wouldn't charge him but once as if you can't fix the problem it's not his fault that it's intermittent and he shouldn't have to pay for it unless you find it and or fix it.

[jcollins]

I power it up and let it sit with an ax plugged up and ready to play and start working on another amp. Every hour or so go and play it and see if it acts up. Sometimes it's just a matter of it heating up enough

I did that.

but also have his cables checked and maybe his setup in case it's something other than the amp.

He says it does it with different guitars, cables.

Try beating the top with your fist and give it a good wack.

Did that.

It could be a loose cap or ground that comes loose when vibrated a certain way. I wouldn't charge him but once as if you can't fix the problem it's not his fault that it's intermittent and he shouldn't have to pay for it unless you find it and or fix it.

Thanks for your ideas. Stuff like this has come in a few times lately. I'm just trying to come up with a policy. It does take up my time to check these things out but, I don't want to leave the customer feeling he's getting a bad deal.

[Twist]

I get those amps in for repair all the time. I've seen enough amps with that complaint that I know all the trouble spots to check. Input jacks, dirty or poorly soldered pots, dirty effects loop jacks, dirty tube sockets, cheesy 1/4" speaker plugs, etc...
Returns are just part of the business and it's frustrating because time is money when your trying to make a living at it. I make it a practice to cover every possible fault in the amp and I seldom have an amp to come back. I've never charged a customer twice for the same problem unless it's been several months or a year. Once in a while I have a customer bring an amp in that claims the amp didn't work right as soon as he got it home only to discover that it had been over a year since I had worked on it and it's a totally different problem now. I guess some people think your married to the amp forever once you have repaired it. I stress to customers to immediately let me know if a repair is not right and to resolve it now. Due to the rough abuse people have on their equipment I warranty my work for 60 days, tubes for 90 days and speakers for 1 year.

[Valvehead]

i fix about 20 little marshall combos a year . Its usually the input jack or the output chip . after that its probably a bad solder joint.

I would just stick a new jack in it if you cant find anything. The factory jack WILL FOR SURE disentegrate soon enough. Then if my customer says it acts up again, i just charge for parts after that. Luckily you can get those boards out fairly easily.

[Enzo]

When the customer tells me it can't be the guitar or the cords, I invite him to bring his axe and cords into my shop and demonstrate the problem. I'm not calling him a, liar, I just want us all to be on the same page. He may perceive things differently. And when he jiggles the input, he is also sending mechanical vibration into the board.

I have been in enough bands to know that cords are usually a clusterfuck of wire. I tried a couple cords usually means he dragged yet another tired old cord out of the bag. TWO bad cords is not out of the question.

I'd be looking for cutout contacts on the headphones jack or something equivalent. I'd be looking for cracked solder under pots along the panel, or for that matter cracked pots.