What exactly causes this?

[S.A.T.O.]

A while back I mentioned in a thread that my JCM 900 would sound great and then the volume would drop off dramatically almost to a whisper, and then come back to full volume. The tubes were ok. I just had the amp re-tubed and re-biased. Someone suggested I spray electronics cleaner into the main input jack, then the effects loop and work a guitar cable in and out of the jacks a few times. It worked! I haven't had an issue since.

Last night at a gig I was using my JCM 2000 and the same thing happened. Crushing tone from the start and then the sound dropped off, came back full, dropped off...I turned the standby off for a minute. I was worried I had a bad tube as I haven't had that amp worked on in a while. Tubes were ok. This happened in the middle of a 22 song set, went on for about 4 songs and then stopped and I made it the rest of the way without a problem. Amp sounded as crushing as ever. I got home this a.m., sprayed the electronics cleaner in the input and effects jacks and I played at a real low volume for over an hour with no problem, no volume drop.

I'm surprised it would happen to this amp, I baby this thing. I only play it at gigs so at most it's used 4 times a month. I have a cover on it all the time and when I do play it the volume is never past four on either channel. What exactly is happening in those jacks that causes this?

I'm bringing it to my amp guy for a checkup just in case. This 2000 is my tone, I can't mess around with this thing.

 

[S.A.T.O.]

I apologize I just realized I should have this in the Workbench section

 

[Micky]

Sounds like a flakey jack. Replace the bad one...
Finding it will be the hard part.

 

[Australian]

I once had that problem because of a scratchy bass potentiometer.

 

[TwinACStacks]

SATO, On a DSL be Damn careful it isn't a problem with the Output jacks, check the ground mods on the First post in the "Joey Mods" thread in the workbench section, for an explanation and fix.

TWIN

 

[DSL 50]

I am having this very exact issue with my Mesa MK III

Seems to mostly only happen if something is in the loop
(tried many different effects and cords to rule out)

Will have to try the contact cleaner thing.

 

[S.A.T.O.]

SATO, On a DSL be Damn careful it isn't a problem with the Output jacks, check the ground mods on the First post in the "Joey Mods" thread in the workbench section, for an explanation and fix.

TWIN

Thought of that too but I've never used anything but the 16 ohm jack in the back, I think that ground issue was for the 8/4 ohm's

 

[steevo]

sato, if u use ur effects loop i was having this problem till i hit my effects loop jacks and db button with contact cleaner, the problems been gone ....for now
I am jumping my effects loop and my db switch is in the OUT position

 

[steevo]

i also re-seated and contact cleaned my tubes as well. I have to remember try one fix at a time , then i know which one worked...lol

 

[ricksconnected]

following.

 

[Gianni]

 

[Dogs of Doom]

he's also new...

to the forum steevo...

 

[ricksconnected]

oh I didn't see that. hey steevo,

 

[BowerR64]

sorry for the miss information

 

[Gianni]

 

[BowerR64]

my bad

 

[Gianni]

my bad

I was just teasing you, mate! This could have just as easily happened to me too.

You shouldn’t have deleted your post though, as, despite being 4 years late, it was still both relevant and useful.

 

[paul-e-mann]

Clean all your inputs, pots and tube sockets with Deoxit all at the same time and let it dry real good. Also clean all your pedal inputs in your chain as well. Your tone will dramatically change for the better and increase its reliability.

 

[BowerR64]

I was just teasing you, mate! This could have just as easily happened to me too.

You shouldn’t have deleted your post though, as, despite being 4 years late, it was still both relevant and useful.

I didnt bump it, but i also dont look at the dates to see when they were started i need to i guess.