Mesa Walkabout static in signal

jordie65 · #1 04-24-2011, 03:27 AM

Hi there,

I recently purchased a new mesa scout 12 combo with the 4ohm cab (a few months ago, from an authorised dealer in another state ) and have had no issues with it, i only use it at rehearsals so it has yet to even see the inside of the van.

Today when i turned on i noticed the signal was coming and going in strength and when i let a not ring out static would gradually come into the signal and it would begin to alternate between totally cut out and barely on and distorted.

i have the model with the silver face and black detailing around the pots. I have the effects loop bypassed and have given the input jack a clean. running my bass into the return jack also yielded the same issues. turning knobs does not create any extra noise and i have isolated the head as the issue. i swapped the head out of the signal chain for my orange head and there were no issues (neat tone with that head/cab combo but more on that another day)

The static in the signal thing is more apparent when i play quieter and when i play with a very soft touch the problem seems more pronounced with the signal frequently cutting in and out, possibly just at the volume its easier to perceive the static?

I took the head out of the cab and noticed when i moved the head about there was what felt like a heavy object loose inside the head. After taking off the outer panel i discovered what i think is the output transformer, its a cylindrical plastic covered thing with what looks like large amounts of copper wire under the plastic, was not properly secured to the chasis and was able to move around a small amount.

Both the pre amp and the driver tubes appear to be properly seated though i'm not too sure how to test them out as i have no spare tubes.

I have already read ALL of the megathreads before i bought this amp and am asking here as it is possible i've overlooked a minor issue and id like to avoid what will very likely be a large headache in getting this fixed under warranty.

ANY help at all would be massively appreciated!

I'm hoping this will be something minor like a bung driver tube or something..

Jordan

RickenBoogie · #2 04-24-2011, 07:54 AM

2 things you can do, first, put a short patch cable in the fx loop, and 2nd, change the tubes out. If neither of those fixes the issue, it's time for an amp tech. Good luck.

jordie65 · #3 04-24-2011, 07:58 AM

Thanks for replying RickenBoogie, I'll try the patch cable tomorrow morning. i ordered some new tubes today from tube depot. I was going to try changing out the stock tubes anyway so there will be no loss for me either way. i will update tomorrow how the patch cable attempt goes.

levis76 · #4 04-24-2011, 08:04 AM

+1 for tubes.

You could try swapping the postions of the tubes. You might have a bad one, and the noise may be minimized by swapping them if the noisy tube is in the V1 position. V1 should be the quietest, best quality tube you have or can get.

If you have the fx loop bypass switch in bypass, then it's not your fx loop. Mesa put that switch in to do exactly what you're going to do with a patch cable, which is bypass it. You can still try it, though I doubt there will be any change.

The "loose" object is the toroidal transformer and I believe it's supposed to be mounted loosely. The one in my Mesa Titan was the same way. Nothing to worry about, just the way they made it, though I'm not sure why they did that.

jordie65 · #5 04-24-2011, 08:08 AM

Quote:

Originally Posted by levis76

The "loose" object is the toroidal transformer and I believe it's supposed to be mounted loosely. The one in my Mesa Titan was the same way. Nothing to worry about, just the way they made it, though I'm not sure why they did that.

Thanks for that Levis, reassuring to be able to rule that out as an issue.

It does seem silly that it's not securely affixed to the chassis!

levis76 · #6 04-24-2011, 08:15 AM

Yeah, it didn't seem right to me, but the hardware was snug. It was engineered to be a bit loose, maybe for vibration damping. I don't know the specific reason, but I'm sure a Mesa expert or an internet engineer will be along shortly to explain it to us mere mortals.

jordie65 · #7 04-24-2011, 09:56 PM

Looking forward to the explanation but your theory makes sense Levis.

As an update put it all back together into its combo this morning and the problem seems worse, the signal is constantly very weak and inconsistent, with intermittent distortion and static. Yesterday the issues came and went.

All this leads me to think (hope) the issue is merely a pre amp or driver tube problem based on what is written on the subject in my user manual. Still if anyone has any ideas for me to try i'm all ears.