Can ANYONE repair a Carvin BX 700 head?

[LHbassist]

I bought a really nice used Carvin BX 700 on here a while back. Well, it was nice looking, anyway. The seller said it was 100% functional. It was not. Later on, I found a thread where the seller spoke of having his tech 'solder some connectors' I did not know that it had issues once, or even then. I should've returned it. When I plugged it in, It made a 'whistling' sound, similar to what my old SVT made when a 12AX7 went bad. No output other than that. So, I ordered a new tube, installed it, and the amp seemed to work. Took it to a gig. Good thing I had my backup. I took it to a supposedly qualified tech here in Reno, and he didn't do a thing. He said there was nothing wrong with it. Well, there certainly is. I love my BX500, and BX 1500 heads. I'd love to get it working.
Sorry if this is a repeat post, but there must be someone familiar with repairing these amps out there.

 

[tubedude]

Most.of the solid state Carvin amps had those problematic ribbon cable connector issues at some timepulling the connectors and cleaning them and the pins resolves problems for a while. The second problem amps of this type have is caused by the tube sockrts being soldered directly to the board. The pressure of installing tubes flexes the traces.If a tube replacement temporarily worked, the socket to circuitboard connection may be intermittent. Touching up the joints with an iron will reestablish sound contact. Ask your tech to flex the board to check for intermittent operation.

 

[Saetia]

I bought a really nice used Carvin BX 700 on here a while back. Well, it was nice looking, anyway. The seller said it was 100% functional. It was not. Later on, I found a thread where the seller spoke of having his tech 'solder some connectors' I did not know that it had issues once, or even then. I should've returned it. When I plugged it in, It made a 'whistling' sound, similar to what my old SVT made when a 12AX7 went bad. No output other than that. So, I ordered a new tube, installed it, and the amp seemed to work. Took it to a gig. Good thing I had my backup. I took it to a supposedly qualified tech here in Reno, and he didn't do a thing. He said there was nothing wrong with it. Well, there certainly is. I love my BX500, and BX 1500 heads. I'd love to get it working.
Sorry if this is a repeat post, but there must be someone familiar with repairing these amps out there.

Sorry you’re having problems and the seller wasn’t forthcoming with issues… kind of bogus especially the usually high Talkbass standards.

Hopefully it’s the normal issue of ribbon cables, really was a common problem. I had a BX1500 and actually miss that amp, one I do regret selling.

 

[agedhorse]

Most.of the solid state Carvin amps had those problematic ribbon cable connector issues at some timepulling the connectors and cleaning them and the pins resolves problems for a while. The second problem amps of this type have is caused by the tube sockrts being soldered directly to the board. The pressure of installing tubes flexes the traces.If a tube replacement temporarily worked, the socket to circuitboard connection may be intermittent. Touching up the joints with an iron will reestablish sound contact. Ask your tech to flex the board to check for intermittent operation.

It’s almost guaranteed not to be the tube socket, because of the style of socket Carvin used and the type of PCB (double-sided w/ plated holes). It’s one of the two most robust tube sockets in the industry and the way they are soldered makes it very robust.

It could be a ribbon cable issue, but it could be a lot of other things too. That’s what a QUALIFIED service tech would troubleshoot.

 

[Reedt2000]

GC has a used one for $400.

With unknown work done to it in the past, the prospect of troubleshooting, possibly undoing old work, finding the issue, getting appropriate parts, and returning it to original working condition could be quite pricey. Might be better to just cut your losses on an older amp, from a now defunct company.

Seating ribbon cables isn't hard to do, might be worth taking it to someone to check that, but price for repairs can easily climb if it's not something like that...

 

[birminghambass]

You bought a bum amp here on TB, why can't you send it back? You shouldn't be stuck with it, especially with the thread you found about previous issues.

 

[mikecd1]

I had a Carvin amp that stopped working at a gig and tried to get Carvin to repair, but they are not repairing amps anymore it seems. Took to a local tech who found the problem, but couldn't get the parts. A qualified tech may be able to repair that amp, but getting parts could be a problem. Since Carvin walked away, I had to as well and hope you can source whatever you need or get the TB'er to help you out who sold the amp.

 

[Smooth_bass88]

Unfortunately this isn’t gig-worthy gear. Best left at home for quiet, contemplative practicing.

 

[Smooth_bass88]

Unfortunately this isn’t gig-worthy gear. Best left at home for quiet, contemplative practicing

 

[LHbassist]

You bought a bum amp here on TB, why can't you send it back? You shouldn't be stuck with it, especially with the thread you found about previous issues.

I did not return the amp to the seller, as in all honesty- I opened it up to check the ribbon connectors, and install a new tube. Therefore, I could not make a 100% claim that it was the sellers obligation to make it right. What this experience has shown me, is it's really hard to trust people at their word. Perhaps the seller has seen this, and regrets selling it in that condition, or they may believe it was working o.k. I don't know. Regardless, I have a nice looking amp that's a paperweight. It isn't like I don't have plenty of amps..and no more gigs. So, what's the point. I'm happy with what I do have.

 

[LHbassist]

It’s almost guaranteed not to be the tube socket, because of the style of socket Carvin used and the type of PCB (double-sided w/ plated holes). It’s one of the two most robust tube sockets in the industry and the way they are soldered makes it very robust.

It could be a ribbon cable issue, but it could be a lot of other things too. That’s what a QUALIFIED service tech would troubleshoot.

Thanks, Andy. I figured if anyone would know, it would be you. Sadly, in Reno- I only know a few electronics techs. I know most of them, as I'm a guitar and bass tech, and a Luthier. If I had learned to fix amps, too, my small shop would be even more cluttered! One tech I took it to said there was nothing wrong with it. I think he was on crack. The amp is clearly broken. I would like to find a qualified tech.. so, anyone know someone that could take a look at it, reasonably, and tell me if it's actually worth it to repair?

 

[agedhorse]

Thanks, Andy. I figured if anyone would know, it would be you. Sadly, in Reno- I only know a few electronics techs. I know most of them, as I'm a guitar and bass tech, and a Luthier. If I had learned to fix amps, too, my small shop would be even more cluttered! One tech I took it to said there was nothing wrong with it. I think he was on crack. The amp is clearly broken. I would like to find a qualified tech.. so, anyone know someone that could take a look at it, reasonably, and tell me if it's actually worth it to repair?

I don't know anybody in your area. The problem you are going to run into is the cost of repair may exceed the amp's value by the time you factor shipping into the equation.

 

[staccatogrowl]

. . in all honesty. .

Is it possible that the amp was fine when shipped, and that the problem(s) occurred during toss & tumble shipping, (in an old amp known for failure)?

 

[LHbassist]

Is it possible that the amp was fine when shipped, and that the problem(s) occurred during toss & tumble shipping, (in an old amp known for failure)?

That thought has occurred to me, but then seeing the seller's old post regarding the head, after I had it for a while, makes me think it was problematic prior to selling and shipping it to me. As they say, 'chalk it up.'

 

[LHbassist]

I don't know anybody in your area. The problem you are going to run into is the cost of repair may exceed the amp's value by the time you factor shipping into the equation.

Thanks, I totally understand. I just assembled, with some real time consuming 'bumps' in the road, a Squier parts bass for a good friend. The body was plywood- not a good candidate for a build, but it was a Late local bassists' instrument that had a lot of sentimental value to both of us. If it were a stranger's, I'd advise them exactly as you have with my situation. He used all premium quality parts, an the bass actually came out quite well.. and he's already gigging with it.
My amp situation, is well covered, with my two Carvin heads, an uber rare Pearce B2P, and old reliable Genz Benz Shuttle 9.0. I also own two combos. I really don't need another amp, but many of us are just obsessive gear hounds.

 

[Gopherbassist]

Thanks, Andy. I figured if anyone would know, it would be you. Sadly, in Reno- I only know a few electronics techs. I know most of them, as I'm a guitar and bass tech, and a Luthier. If I had learned to fix amps, too, my small shop would be even more cluttered! One tech I took it to said there was nothing wrong with it. I think he was on crack. The amp is clearly broken. I would like to find a qualified tech.. so, anyone know someone that could take a look at it, reasonably, and tell me if it's actually worth it to repair?

It's a bit of a drive, but do you have any business that would take you to Sacramento? There are probably more techs there.

 

[eniac]

I bought a really nice used Carvin BX 700 on here a while back. Well, it was nice looking, anyway. The seller said it was 100% functional. It was not. Later on, I found a thread where the seller spoke of having his tech 'solder some connectors' I did not know that it had issues once, or even then. I should've returned it. When I plugged it in, It made a 'whistling' sound, similar to what my old SVT made when a 12AX7 went bad. No output other than that. So, I ordered a new tube, installed it, and the amp seemed to work. Took it to a gig. Good thing I had my backup. I took it to a supposedly qualified tech here in Reno, and he didn't do a thing. He said there was nothing wrong with it. Well, there certainly is. I love my BX500, and BX 1500 heads. I'd love to get it working.
Sorry if this is a repeat post, but there must be someone familiar with repairing these amps out there.

Well, this has about a 0.01 probability of making a difference, but have you tried bridging the effects loop?

The fact that the tech you took it to couldn't find a problem suggests that the problem is intermittent. If that amp were on my bench, I'd open it up and re-fasten every connector and screw I could get my hands on. There's a slight chance one of them's loose or corroded. I've even seen PCB mounting screws doing double duty as ground points, and one or more of those screws have come loose, causing intermittents, noise, and what have you. I've run across that several times over the years.

Have you isolated the problem to either the preamp section or the power amp section? Because if one of the two is working, then the amp has at least some value in its current state.

 

[LHbassist]

It's a bit of a drive, but do you have any business that would take you to Sacramento? There are probably more techs there.

Well, this has about a 0.01 probability of making a difference, but have you tried bridging the effects loop?

The fact that the tech you took it to couldn't find a problem suggests that the problem is intermittent. If that amp were on my bench, I'd open it up and re-fasten every connector and screw I could get my hands on. There's a slight chance one of them's loose or corroded. I've even seen PCB mounting screws doing double duty as ground points, and one or more of those screws have come loose, causing intermittents, noise, and what have you. I've run across that several times over the years.

Have you isolated the problem to either the preamp section or the power amp section? Because if one of the two is working, then the amp has at least some value in its current state.

1. I already unplugged and re-inserted all the connectors.. The seller said in the posts he didn't mention to me, that he had his tech solder some of the connectors. I saw no evidence as to that at all.
2. I seldom go to California- seems to us Reno-ites, that half of California has moved here! Agedhorse, is right. At some point, it makes little or no sense to even bother with it.

 

[LHbassist]

I don't know anybody in your area. The problem you are going to run into is the cost of repair may exceed the amp's value by the time you factor shipping into the equation.

A quick question- would these be of any use to me, or are they the waste of money they seem to be?

Inductance Motherboard Tester Inductor Detector Repair Tool ElectroMagniticic Induction Quick Fault Check Device MaAnt M093 New 2026 Electronic & Accessories: Amazon.com: Industrial & Scientific

Inductance Motherboard Tester Inductor Detector Repair Tool ElectroMagniticic Induction Quick Fault Check Device MaAnt M093 New 2026 Electronic & Accessories: Amazon.com: Industrial & Scientific

www.amazon.com

 

[rodak]

So you point it at each component and it tells you which one is bad? Yeah, I'm sure that works - sign me up!