Mark IV Lead Channel problem

[TheArriaga88]

Hello! its been a while since ive posted, ive since traded in my dual rec head for a mark iv b widebody combo.
Ive had a lot of frustrations with it, mainly i think because ive yet to give it a full retube to breathe some life into it again, previous owner claimed tubes were a year old, but you never really know :?:

Ive been having a problem in the lead channel.
When i take the amp off standby mode with no guitar cable connected the lead master at about 8 and the output at 3 i get some horrible loud squealing, any ideas?

Cheers

 

[tony777]

Probably the input jack that doesn't connect to ground when you pull the cable. The noise is amplified through all the gain stages and then you get the squeel. Listen if it is noisy when in rhythm channels.

 

[dodger916]

Could be a bad triode in a preamp tube. Does the squeal change if you lower the gain and master?

 

[TheArriaga88]

Yeah regardless of the gain drive or Chan. Vol the squealing persists.
I talked to Trent Blake for mesa boogie today, he says it might be a bad volume pot
anyhow im thinking of shipping it off to Petaluma, for a full check up and thorough thorough look through.
has anybody had any experience doing that?

 

[bgh]

Yeah regardless of the gain drive or Chan. Vol the squealing persists.
I talked to Trent Blake for mesa boogie today, he says it might be a bad volume pot
anyhow im thinking of shipping it off to Petaluma, for a full check up and thorough thorough look through.
has anybody had any experience doing that?

After I had my Nomad for a few years it developed a small issue. We have no one within several hours of driving that can service Mesa amps. So, I pulled the chassis and sent it to Mesa. George (don't know his last name) worked on it and did an excellent job. While he was in there, he fixed a few other things too. So, even when you send one in for a specific reason, they do give it a good "once over". Excellent company to deal with.