Fx Loop Broken. Gig In 2 Weeks. Possible To Replace Loop Circuit?

[ADZG]

Hi there,

I have a problem with my JCM2000 DSL's fx loop.
Basically the problem is that the amp works for about 10 seconds then there is volume drop. This is when there are cables plugged into the Fx loop. When I take the cables out the amp works fine.

I just got this amp serviced/repaired for this very issue in Feb and fired it up tonight as I have some gigs coming up soon. Lasted 30 seconds and same problem is back. Although this time there was no horrible fizz and bang when switching the standby switch off.

At the time the tech said he replaced the jacks and fixed some soldering issues.

The gig is in 2 weeks and I am an amp down.. I have a backup that I can use but I am paranoid that one will go down also haha.

Is it possible to replace the fx loop circuit on my amp? Sorry for such a simple/dumb question but I have no idea. I don't want to get rid of the amp and buy something else but I just can't keep having this problem. Even when the amp works (before having some sort of issue) I can't play with confidence as I am just waiting for something to give way.

Please let me know if I can replace the FX loop circuit to fix any issues. The amp is a 1998 model but has been rebuilt with a 2006 PCB and regularly serviced. I always power the amp off my furman power conditioner.

Cheers

 

[paul-e-mann]

Hi there,

I have a problem with my JCM2000 DSL's fx loop.
Basically the problem is that the amp works for about 10 seconds then there is volume drop. This is when there are cables plugged into the Fx loop. When I take the cables out the amp works fine.

I just got this amp serviced/repaired for this very issue in Feb and fired it up tonight as I have some gigs coming up soon. Lasted 30 seconds and same problem is back. Although this time there was no horrible fizz and bang when switching the standby switch off.

At the time the tech said he replaced the jacks and fixed some soldering issues.

The gig is in 2 weeks and I am an amp down.. I have a backup that I can use but I am paranoid that one will go down also haha.

Is it possible to replace the fx loop circuit on my amp? Sorry for such a simple/dumb question but I have no idea. I don't want to get rid of the amp and buy something else but I just can't keep having this problem. Even when the amp works (before having some sort of issue) I can't play with confidence as I am just waiting for something to give way.

Please let me know if I can replace the FX loop circuit to fix any issues. The amp is a 1998 model but has been rebuilt with a 2006 PCB and regularly serviced. I always power the amp off my furman power conditioner.

Cheers

Clean the effects loop inputs with Deoxit. Spray in the inputs and stick a cable into them a dozen times or more to clean it out.

 

[ADZG]

The jacks are brand new and so are my cables.

 

[67Mopar]

If doable, I would purchase a reliable amplifier. Ceriatone has what you need, but I would request a set of Classic Tone transformers.

 

[Michael Roe]

Take the amp back to the service center and ask them to finish the repair.

It could just be the FX loop +4/-10db switch

 

[ampmadscientist]

Hi there,

I have a problem with my JCM2000 DSL's fx loop.
Basically the problem is that the amp works for about 10 seconds then there is volume drop. This is when there are cables plugged into the Fx loop. When I take the cables out the amp works fine.

I just got this amp serviced/repaired for this very issue in Feb and fired it up tonight as I have some gigs coming up soon. Lasted 30 seconds and same problem is back. Although this time there was no horrible fizz and bang when switching the standby switch off.

At the time the tech said he replaced the jacks and fixed some soldering issues.

The gig is in 2 weeks and I am an amp down.. I have a backup that I can use but I am paranoid that one will go down also haha.

Is it possible to replace the fx loop circuit on my amp? Sorry for such a simple/dumb question but I have no idea. I don't want to get rid of the amp and buy something else but I just can't keep having this problem. Even when the amp works (before having some sort of issue) I can't play with confidence as I am just waiting for something to give way.

Please let me know if I can replace the FX loop circuit to fix any issues. The amp is a 1998 model but has been rebuilt with a 2006 PCB and regularly serviced. I always power the amp off my furman power conditioner.

Cheers

OK Test One
Plug a guitar or a music player into the effects return.
Now raise the level up, and see if you are getting a good signal into the rest of the amp.

Let this play for a while if there is sound, and verify that it keeps working.
We are testing the effects return to see if the problem is the send, or the return.

Test two:
plug a guitar cable between send and return jacks.
Now play the amp for a long while and see if it all keeps working.

Report your results...

How do you know that this problem is not caused by the effects that are plugged into the loop?

Test 3
Plug effects into the loop. (ONE effects unit ONLY)
Now test the amp and see if the problem is still there.
Plug effects into the loop ONE at a time. Test each effects pedal -separately not together with other pedals...
Now, can you narrow this down to just ONE effects pedal? or does ANY pedal in the loop cause the same problems?

The more I read what you are saying, the more it sounds like a bad effects pedal.

 

[ADZG]

thanks for your replies. I’ll organise to take it to a different tech as the tech that it came from isn’t working/slow due to recent personal issues. I need the amp fixed fast for these shows.

As for the effects causing the problem well I don’t think that would be an issue.
I’m only running a tc electronic flashback and a mxr6 band eq. The board is powered by a one spot and built by a professional store that specialises in pedalboards. All my cables are Mogami.

I just need to know if it’s possible to buy a new fx loop to install or is it part of the main pcb. The amp is getting older now so I would prefer a fresh circuit installed

I don’t want to buy a new amp. I like the tone from this amp. If I did have to I would look into a jvm, 2203 or evh 5150. I just want something reliable.

Looking forward to your replies.

Kind regards

 

[Chris-in-LA]

Not sure why you are so set on buying an effects loop but seem to be unwilling to run a few simple tests. But, of course, you can buy anything or replace anything you want, it’s only money.

And.... only running two pedals? Just go in the front for now and take the loop out of the equation.

 

[ADZG]

Not sure why you are so set on buying an effects loop but seem to be unwilling to run a few simple tests. But, of course, you can buy anything or replace anything you want, it’s only money.

And.... only running two pedals? Just go in the front for now and take the loop out of the equation.

Thanks for your advice.
I have already run the tests that have been mentioned.
I have drawn the same conclusion. It is the fx loop circuit that is faulty. Since the amp is 21 years old i figured it may be easier to replace the whole fx loop since this has been an ongoing issue for me over many years with this particular amp. My other JCM2000 is fine with the same setup.
Yes it is only money but if money can buy me peace of mind in the form of a reliable and new loop then why not?

My 2 pedals need to go in the loop as delay works best there for me and the eq is used for a volume mid boost. I simply don't get the headroom from the eq going into the front of the amp. I also have other pedals going into the front like wah, tuner, od, noise supressor etc.

 

[paul-e-mann]

The jacks are brand new and so are my cables.

Go pickup a DSL100HR you can get them used all day for $600, it will be lightyears more reliable than those old DSL2000's, or buy a new one and return it after the gig. Or keep it and stop dumping money into your old unreliable DSL.

I heard you say you don't want a new amp, then the only solution is find a better tech in your area and hope he can get it fixed in time, 2 weeks away would be cutting it close as most good techs are back logged for weeks and could take longer if they gotta order parts.

 

[ampmadscientist]

Thanks for your advice.
I have already run the tests that have been mentioned.
I have drawn the same conclusion. It is the fx loop circuit that is faulty. Since the amp is 21 years old i figured it may be easier to replace the whole fx loop since this has been an ongoing issue for me over many years with this particular amp. My other JCM2000 is fine with the same setup.
Yes it is only money but if money can buy me peace of mind in the form of a reliable and new loop then why not?

My 2 pedals need to go in the loop as delay works best there for me and the eq is used for a volume mid boost. I simply don't get the headroom from the eq going into the front of the amp. I also have other pedals going into the front like wah, tuner, od, noise supressor etc.

You are not diagnosing the problem, there is no help if you won't diagnose.

Test the send, test the return, test the pedals, test bypassing the loop,
report the exact results to the forum step by step,
then maybe forum can help you.
Then what you report will also help other players in the future also.

"It is the fx loop circuit that is faulty."

Is not solving the problem. So buy a new amp?

 

[ADZG]

Thanks for the advice. The amp is at the tech now.

 

[ADZG]

Go pickup a DSL100HR you can get them used all day for $600, it will be lightyears more reliable than those old DSL2000's, or buy a new one and return it after the gig. Or keep it and stop dumping money into your old unreliable DSL.

I heard you say you don't want a new amp, then the only solution is find a better tech in your area and hope he can get it fixed in time, 2 weeks away would be cutting it close as most good techs are back logged for weeks and could take longer if they gotta order parts.

Thanks mate, great advice.
I had one of the new dsl100heads from Vietnam and sold it as it didn’t have the tone that the old uk ones did. In hindsight I should have kept it as a backup. I don’t want a new amp as I don’t want to spend more than a few hundred bucks (the cost of amp repair).
If I had to buy a new amp I would but I’m worried I’ll have similar issues. New jvm heads are quite complex circuits many things can go wrong in theory, 2203 is simple but I need something more versatile and 5150iii is great but has a large number of pre amp tubes and made in China which worries me about reliability. What if I found a good 2nd hand jcm2000 from the last year’s of production something around 2010. Could be more reliable but you never know what’s happening on the inside and no warranty etc. I’ll see what the amp tech says and then I’ll make a decision. Thanks again

 

[paul-e-mann]

Thanks mate, great advice.
I had one of the new dsl100heads from Vietnam and sold it as it didn’t have the tone that the old uk ones did. In hindsight I should have kept it as a backup. I don’t want a new amp as I don’t want to spend more than a few hundred bucks (the cost of amp repair).
If I had to buy a new amp I would but I’m worried I’ll have similar issues. New jvm heads are quite complex circuits many things can go wrong in theory, 2203 is simple but I need something more versatile and 5150iii is great but has a large number of pre amp tubes and made in China which worries me about reliability. What if I found a good 2nd hand jcm2000 from the last year’s of production something around 2010. Could be more reliable but you never know what’s happening on the inside and no warranty etc. I’ll see what the amp tech says and then I’ll make a decision. Thanks again

If you open an old and new DSL head they are night and day, the old is jam packed with electronics the new is very simple and very empty inside, I always said less is more, the less inside the less chance of something going wrong. If you didn't like the tone of the current DSL100HR you are correct they have been slightly revoiced, if you need a backup maybe you should look at the previous rendition the DSL100H these are probably more in line tonally and functionally with the old DSLs, or do like you said find the last version of the old ones. Good luck with this, I hope you get it all sorted out and your DSL fixed.

 

[anitoli]

What does the amount of tubes have to do with anything? I have run 6100's for ever with 11 tubes in them....................