Trouble please help

[Geiri]

Ok

the clean channel on my mk4 is acting strange. When I play softly it's barely audible at bedroom levels but when I strum hard the sound comes in and then dies very quickly ???

R2 and the lead channels are fine. What's wrong with my amp ???

Thanks

Geiri

 

[zebpedersen]

Try switching the preamp tubes around - if you move them and find that you change the fault to a different channel then it's a tube.

 

[stokes]

I doubt it is a tube problem,or you would have problems in all the channels.V1 and 2 are the preamps for the clean channel,the lead channel also use these tubes, just use another tube for the extra drive.So if it is a tube problem it would have to be V1 or 2 and since the other channels use these tubes the problem would be there as well.

 

[primal]

I have had this identical problem on my RK.

Let me guess, it is sort of like a noise gate effect where you have the threshold set to high. You hit the string hard it sounds fine, then all of a sudden, as the sound dies, it cuts out like your going below the threshold of a noise gate.

Replacing preamp tubes actually made it much better to me. So much so that I thought the problem was gone. But I have noticed every once in a while it happens again. Especially after channel switching.

If you find this out, please let me know what it was.

 

[Geiri]

Ok this may sound weird but I've located the problem.

The problem was a digital tv box that plugs into a wall socket and sends/receives digital signal via electricity.

I moved the amp into another room after taking it to a tech and bam problem gone. I discussed this with my tech, and the phone company techs and apparantly this digital wallwart for my tv is super sensitive to anything which is using the same wiring path it is plugged into. It most certainly will not play nicely with an power hungry guitar amp and thus the amp was picking up interference.

So they got a divorce and are now living in separate rooms in my home. :mrgreen: :mrgreen:

 

[stokes]

Very strange.Why only the clean channel?

 

[Geiri]

I really don't know why it only affected the clean channel, but I think what was really happening is that this digital device was somehow starving the amp for power.

I plugged the amp in at my techs house and started off on the clean channel and he asked "what's wrong with it"

Strange indeed, But it's all working now and to make sure I wasn't loosing my mind I took it to the forbidden zone again and played it there and it sounded the same. Clean channel choked or starving and the effects loop was like it had an 80's metal switch permanently on. No matter what I plugged in the loop ehx delay, dl4, or my boss gt8 it all had this strange metallic foil or sheen over the sound on the lead channel. But with the loop off the lead channel sounded and acted like normally.

I really hope it's just this digital wall wart that is the problem, it would break my heart if my amp was dying.

 

[fretout]

No matter what I plugged in the loop ehx delay, dl4, or my boss gt8 it all had this strange metallic foil or sheen over the sound on the lead channel. But with the loop off the lead channel sounded and acted like normally.

Did you check the volume and send levels on your pedals? Maybe the controls on the pedals got bumped around. If all the pedals were working correctly, I would assume that you have a problem with the FX loop somewhere. If you have already verfied that the preamp tubes are fine, you may want to take a look at the internals inside the chassis to see if there is anything wrong with the solder joints, ect.

 

[Geiri]

Since I moved the amp to a different room, I tried all my pedals again and they worked fine. No more metallic sheen or foil on top of the amps tone.

 

[fretout]

Since I moved the amp to a different room, I tried all my pedals again and they worked fine. No more metallic sheen or foil on top of the amps tone.

I'm glad it's working correctly now! You may want to invest in some sort of power conditioner/voltage regulator just to make sure the amp will work properly no matter what room it's in.

Cheers!

 

[Geiri]

I live in Iceland and I've never in my life experienced anything like this before. The electricity here is very stable, but after this incident, a power conditioner is on my list.

 

[Geiri]

No matter what I plugged in the loop ehx delay, dl4, or my boss gt8 it all had this strange metallic foil or sheen over the sound on the lead channel. But with the loop off the lead channel sounded and acted like normally.

Did you check the volume and send levels on your pedals? Maybe the controls on the pedals got bumped around. If all the pedals were working correctly, I would assume that you have a problem with the FX loop somewhere. If you have already verfied that the preamp tubes are fine, you may want to take a look at the internals inside the chassis to see if there is anything wrong with the solder joints, ect.

Holy crap it's doing it again.

Sat down ready to play and have fun and wham I'm stuck with a crappy clean sound and an ugly sounding lead channel again. Arrrrrrrrgh :evil: :evil:

I guess I'll have to change techs or tear this thing apart my self to find out what's wrong. It's funny tho, the amp was a dream for a few day's after the pointless trip to my tech guy.

I'm pretty sure now that it has something regarding the effects loop. Cause everything sounds ok with it turned off.

So much for the digital wallwart theory :lol:

I guess I have to find my a new tech or send it to mesa.

 

[fretout]

No matter what I plugged in the loop ehx delay, dl4, or my boss gt8 it all had this strange metallic foil or sheen over the sound on the lead channel. But with the loop off the lead channel sounded and acted like normally.

Did you check the volume and send levels on your pedals? Maybe the controls on the pedals got bumped around. If all the pedals were working correctly, I would assume that you have a problem with the FX loop somewhere. If you have already verfied that the preamp tubes are fine, you may want to take a look at the internals inside the chassis to see if there is anything wrong with the solder joints, ect.

Holy crap it's doing it again.

Sat down ready to play and have fun and wham I'm stuck with a crappy clean sound and an ugly sounding lead channel again. Arrrrrrrrgh :evil: :evil:

I guess I'll have to change techs or tear this thing apart my self to find out what's wrong. It's funny tho, the amp was a dream for a few day's after the pointless trip to my tech guy.

I'm pretty sure now that it has something regarding the effects loop. Cause everything sounds ok with it turned off.

So much for the digital wallwart theory :lol:

I guess I have to find my a new tech or send it to mesa.

Are you sure it's not a problem with one of your pedals? Try setting up your FX Loop like you normally would and start taking pedals out of the loop one at a time. Determine if one of your pedals is affecting the signal going to the amp. If the amp still doesn't sound right, then try taking the chassis out and inspect the solder joints on the FX Loop jacks. If everything looks right, you may have a more serious problem, in which case hire a better tech! :lol:

Best of luck! Hopefully everything works out ok.

 

[stokes]

When troubleshooting any amp,it is imperitive to have no pedals in the mix.Just use the amp.If the problem is still there it is your amp,if the problem goes away it is likely a pedal.If you experience the problem with nothing in the loop,try connecting the the send and return jacks with an ordinary guitar cable.If the guitar jack fixes the problem you have to either clean the contacts on the jacks or change them altogether.It is a very common problem with Mesa amps with effects loops.

 

[Geiri]

Thanx dudes for all your replies

well this is what's going on. I'm currently only using one pedal, the boss gt 8. The problem described above seems to live only in the tweed mode. When I took it to the tech he connected the send and return with one cable and everything was fine in tweed mode there.

So here is my question, how do I clean the contacts on the jacks, and when you say contacts are you referring to the solder points inside the amp or is it the jacks them selves that need cleaning ?

Thanx

Geiri

 

[stokes]

You will have to open the chassis to clean.The jacks tend to become oxidized when thay arent used often,and when they are used often the shorting contact becomes "sprung" and doesnt make good contact,which requires new jacks installed.Sometimes it is good enough to just put some contact cleaner on a jack and insert it in and out of the problem receptacle a few times.Your problem is more likely the shorting contact,which doesnt come in contact with the jack itself,so you would have to open the chassis.Quite often it is necessary to change the jacks.I cant believe your tech did the loop test with the guitar cable and didnt fix the problem.I dont know what he charged you to look at the amp,but if it were me,I would have changed the jacks for just the price of the parts,as long as you were paying for the diagnosis already.Its an easy fix and the parts are only a couple of bucks.

 

[fretout]

Thanx dudes for all your replies

well this is what's going on. I'm currently only using one pedal, the boss gt 8. The problem described above seems to live only in the tweed mode. When I took it to the tech he connected the send and return with one cable and everything was fine in tweed mode there.

So here is my question, how do I clean the contacts on the jacks, and when you say contacts are you referring to the solder points inside the amp or is it the jacks them selves that need cleaning ?

Thanx

Geiri

The quickest and easiest way is to grab a Q-Tip and just swab the inside if the jack. If that doesn't work, I have heard of people using Naphtha (commonly found in lighter fluid) to clean the jack. Naphtha is popular because it will clean impurities from metal surfaces and will evaporate and not cause rust.

 

[Geiri]

Cool

Thanx alot dudes for your help.

Geiri