Mark V with Static noises

[mace]

Hi, My Mark V has developed a strange problem. There is a static sound present, sort of sounds like popping (sort of like a bad power tube rustling sound, or a little like when your cell phone interferes with older sound equipment). I have rolled all tubes, disabled fx loop, disconnected guitar and the sound is still there. All power levels, all modes it is still present. I moved the amp to a different floor of the house, hooked up a different cab, but the static is still there.

So, what is really weird.. It is most prominent on Tweed and Channel 3. In Tweed mode, with the gain at zero, the static is still there (gain setting has no effect). However, in Channel 3, with the gain at zero there is no static and with the gain at 12 o'clock the static is there. The static is not very noticable on Bold or Channel 2 any mode (present, but not as strong as in Tweed or Channel 3).

I've contacted Mesa but I'm curious if anyone here has any idea what this could be?

Thanks,

Mace

 

[pwoz]

I had an issue last year and I posted here:

http://forum.grailtone.com/viewtopic.php?f=33&t=71451

Maybe it's similar. I ended up changing V1.

Here are a couple youtube vids I put the sounds:

https://www.youtube.com/watch?v=fS1sz1CTrxM

https://www.youtube.com/watch?v=HSP_PDe8h2M

 

[mace]

I sent an audio file and demo to Mesa and they want the amp sent in to repair. Seems to not be a normal condition. Certainly is not a bad tube (I changed all of them). Good thing it's under warranty.

Mace

 

[bandit2013]

I would not doubt it is a preamp tube. Some of the channel voices will change the plate voltages on the preamp tubes thus changing their operating characteristics. Tweed mode seems to drive the preamp tubes harder but with reduced gain.

Also I have noticed that if you have a poor Rectifier tube it can contribute to static noise, I have run into that issue several times even at 90W power setting since the Rectifier parallels the two high current diodes. Sputtering noises are generally preamp tubes if it sounds like an old transistor radio dialed in to a frequency with no audible sound except for typical chatter. Almost if the corona surrounding the cathode is having a release of energy or the cathode is boiling.

Best to get them to look at it.

 

[mace]

Yep, I changed *all* the tubes (preamp, power, rectifier) and the problem persists. It is not a tube issue in this case. I think a bad component. Now the challenge is getting it packed up so FedEx doesn't destroy it.

Thanks,

Mace

 

[nsnyder]

I had a very similar issue, which was resolved by a local tech. He was a little vague in his info but I did get out of him that it was a resistor somewhere.

 

[bandit2013]

Hope you get it fixed.