Mark V Channel 2 Problem

[tmg]

Hello! My first post here. I have owned my Mark V since 2010. I am just a regular guitarist who generally plays in his home studio and seldomly plays live. But when I do, I love the Mark V. I have never had any problems with it in 13 years, exept for tube replacements. The rectifier tube seems to be the most frequent of replacements. I will explain the problem the best I can. I am hoping it may be something simple before I have to ship my Mark V off or drive several hours to the nearest trusted repair center.

First, I use the FCB1010 to switch channels on the Mark V with TC Electronics G Major. The mesa footswitch is connect also but I only use it to mute the amp when switching guitars and on start up and shutdown. I have used this system for 13 years flawlessly until a few days ago. When I am switched to channel 2 with Crunch and Mark 1 Thick selected, it sounds like some kind of switching, clicking or chattering is going on. It is like the amp is trying to switch channels if that makes since. While this is going on, the sound will cut in and out. This happens randomly. Sometimes it does not and some times it does. Now, this does not happen on channel 2 when Edge or Mark 1 is selected. It only happens when Crunch is selected with Mark 1 Thick. Furthermore, when the clicking starts in this Crunch setting and then I switch to Mark Normal it seems to settle a little. Everything works great except for channel 2 when set to Crunch with Mark 1 Thick, and just slightly with Crunch and Mark normal. This does not happen on channels 1 and 3.

I have tried different tubes, both pre and power to no avail. I used my JSX to see if it was the G Major or even the FCB1010. I have checked my cables and all seems good. I am just checking if some one has had a similar situation and hoping for some easy fix. I hope I have explained this enough for some one to understand. thanks for any info.

 

[Nandrewjackson]

You're using a g major to a fcb1010 with the 1/4" channel switching Jack's on the mkv at the same time as the mesa footswitch with 8 pin DIN?
That sounds like a recipe for confusing the mkv switching logic.

 

[Eevil]

Hello! My first post here. I have owned my Mark V since 2010. I am just a regular guitarist who generally plays in his home studio and seldomly plays live. But when I do, I love the Mark V. I have never had any problems with it in 13 years, exept for tube replacements. The rectifier tube seems to be the most frequent of replacements. I will explain the problem the best I can. I am hoping it may be something simple before I have to ship my Mark V off or drive several hours to the nearest trusted repair center.

First, I use the FCB1010 to switch channels on the Mark V with TC Electronics G Major. The mesa footswitch is connect also but I only use it to mute the amp when switching guitars and on start up and shutdown. I have used this system for 13 years flawlessly until a few days ago. When I am switched to channel 2 with Crunch and Mark 1 Thick selected, it sounds like some kind of switching, clicking or chattering is going on. It is like the amp is trying to switch channels if that makes since. While this is going on, the sound will cut in and out. This happens randomly. Sometimes it does not and some times it does. Now, this does not happen on channel 2 when Edge or Mark 1 is selected. It only happens when Crunch is selected with Mark 1 Thick. Furthermore, when the clicking starts in this Crunch setting and then I switch to Mark Normal it seems to settle a little. Everything works great except for channel 2 when set to Crunch with Mark 1 Thick, and just slightly with Crunch and Mark normal. This does not happen on channels 1 and 3.

I have tried different tubes, both pre and power to no avail. I used my JSX to see if it was the G Major or even the FCB1010. I have checked my cables and all seems good. I am just checking if some one has had a similar situation and hoping for some easy fix. I hope I have explained this enough for some one to understand. thanks for any info.

Hello.

Does it have the same issue without the Mesa footswitch?

 

[tmg]

You're using a g major to a fcb1010 with the 1/4" channel switching Jack's on the mkv at the same time as the mesa footswitch with 8 pin DIN?
That sounds like a recipe for confusing the mkv switching logic.

Yes. I’m not at my amp right now but from back facing back the right knob is turned to foot switch and the left to ALL. I think. It has always worked for me. I don’t know. I’ll check later tonight and disconnect footswitch. Thanks

 

[tmg]

Hello.

Does it have the same issue without the Mesa footswitch?

I will try this tonight when I get home thanks. .

 

[tmg]

Okay I disconnected the Mesa foot switch while using fcd1010 with g major switching channels. and all worked good for a while and then it started clicking again. However it’s not as bad and as I kept playing it stopped. It has helped but ever so often it’ll start clicking and then stop. As long as I keep it to mark normal all is great. It’s just weird. I’ll keep playing on it this week and monitor it. I have a gig coming soon and just can’t be without the mark v. It’s just so clean sounding. I don’t use channel 2 that much but only occasional.

 

[rarebitusa]

Well it's possible the clicking could be related to the 12 VDC supply and it's bridge diode circuit. I had relay chatter & clicking on my V:90 intermittently for a long time. It was solved by replacing the diodes. Or probably more likely the relay related to Ch 2 Crunch selection.

If you select remove the FCB1010 cables and just select Ch 2 from the rear chan controls do you get any chatter?

 

[ATR1]

Remove your cell phone out of the room. I chased a click in my amp and it ended up being interphence with my cell phone causing a clicking. Crazy!

 

[tmg]

Well it's possible the clicking could be related to the 12 VDC supply and it's bridge diode circuit. I had relay chatter & clicking on my V:90 intermittently for a long time. It was solved by replacing the diodes. Or probably more likely the relay related to Ch 2 Crunch selection.

If you select remove the FCB1010 cables and just select Ch 2 from the rear chan controls do you get any chatter?

Yes, I’ve tried everything with same result. But it only chatters on channel 2 when selected crunch with mark thick. What you said might be wrong will probably result in having to send it off?

Well it's possible the clicking could be related to the 12 VDC supply and it's bridge diode circuit. I had relay chatter & clicking on my V:90 intermittently for a long time. It was solved by replacing the diodes. Or probably more likely the relay related to Ch 2 Crunch selection.

If you select remove the FCB1010 cables and just select Ch 2 from the rear chan controls do you get any chatter?

Yes still chatter
What you said might be wrong will result in sending it off?

 

[tmg]

Remove your cell phone out of the room. I chased a click in my amp and it ended up being interphence with my cell phone causing a clicking. Crazy!

Yes, I learned that a long time ago.

 

[Nandrewjackson]

If your sane exact setup used to work fine and now it doesn't, likely an internal component failure.

 

[rarebitusa]

Yes, I’ve tried everything with same result. But it only chatters on channel 2 when selected crunch with mark thick. What you said might be wrong will probably result in having to send it off?

Yes still chatter
What you said might be wrong will result in sending it off?

Well if it's the diodes, which is a known problem in the V:90, then yea a tech should deal with it. I did replace the diodes, 12V reg and caps on mine and that was not a fun job at all.

In the meantime you could just continue to workaround it. Mine chattered for years before addressing the diodes and it never failed. But that is taking on risk for sure.

 

[bandit2013]

Why is everyone trying to think thick voicing switch does anything for Crunch or Edge. It does absolutely nothing to the tone of the amp. Thick voicing is only associated with the Mark 1 mode. If there are no issues with the switch in the normal position, just leave it there. If the normal/thick switch is supposed to do something for edge or crunch, what is the effect? I have only found it alters the voice of the Mark I mode. If the switch set to normal fixes the issue, it is not like you can switch between modes using the footswitch control or external relays with a midi interface. I did read the manual when I got my amp. Sure, explored what the switch does. There could be something up with the amp though, I doubt the switch position is resulting in issues with the relays or channel matrix. However, are you using Variac power or Full power? I have personally had more issues with Variac power and making use of the footswitch due to potential voltage drop issue related to the 12V supply.

Copied from the on-line manual:

 

[tmg]

Why is everyone trying to think thick voicing switch does anything for Crunch or Edge. It does absolutely nothing to the tone of the amp. Thick voicing is only associated with the Mark 1 mode. If there are no issues with the switch in the normal position, just leave it there. If the normal/thick switch is supposed to do something for edge or crunch, what is the effect? I have only found it alters the voice of the Mark I mode. If the switch set to normal fixes the issue, it is not like you can switch between modes using the footswitch control or external relays with a midi interface. I did read the manual when I got my amp. Sure, explored what the switch does. There could be something up with the amp though, I doubt the switch position is resulting in issues with the relays or channel matrix. However, are you using Variac power or Full power? I have personally had more issues with Variac power and making use of the footswitch due to potential voltage drop issue related to the 12V supply.

Copied from the on-line manual:

View attachment 2077

I do recall reading that about mark thick. My v:90 is old that some of the writing has worn away but I’m sure it’s always full power but I may switch it down without thinking sometimes. It’s just that I noticed this is the only time channel 2 chatters (crunch with mark thick). I always have mark thick selected.

For now on I’m just using mark 1 on channel 2. It solves the problem for now and I discovered it sounds better than crunch any way, imo. I guess I used the crunch because it is a little louder in volume than mark 1 and better fit certain older rock songs. Like I said before my main channels are 3 mark 4 for and 1 fat. I only use 2 for a few select parts/songs.
But I don’t know, after playing with mark 1 it does have some great smooth lead and rhythm tones. I discovered my love for it through this ordeal.

Anyway this winter I might send it in just to have it checked out because it is over 13 years old.

 

[bandit2013]

That sounds like a plan. The schematics are not complete so the full matrix of what gets switched for each mode is not clear. I have found all of the relays but nothing specific for the thick voicing. I assume it is probably one of the bypass capacitors on V3A. Bold for CH1 is a shunt switch to bypass a grid stopper resistor on V3B.

 

[rarebitusa]

I do recall reading that about mark thick. My v:90 is old that some of the writing has worn away but I’m sure it’s always full power but I may switch it down without thinking sometimes. It’s just that I noticed this is the only time channel 2 chatters (crunch with mark thick). I always have mark thick selected.

For now on I’m just using mark 1 on channel 2. It solves the problem for now and I discovered it sounds better than crunch any way, imo. I guess I used the crunch because it is a little louder in volume than mark 1 and better fit certain older rock songs. Like I said before my main channels are 3 mark 4 for and 1 fat. I only use 2 for a few select parts/songs.
But I don’t know, after playing with mark 1 it does have some great smooth lead and rhythm tones. I discovered my love for it through this ordeal.

Anyway this winter I might send it in just to have it checked out because it is over 13 years old.

Yea Mark 1 mode is actually a good one, eq'ng it a bit can remove the blanket... initially I wasn't into it but I didn't really understand how to tweak it, now I dig it more. Have found 45W / diode mode gives it more attack.

 

[bandit2013]

I actually started getting into tweed and edge a bit more. before, both were rather ice pick modes I had difficulty understanding why Mesa would do this on a Flagship amp. Sure, CH3 has been an ice pick too but that is an unrelated issue. Mesa STR441 power tubes did cure most of this as well as change in preamp tubes to something other than the Mesa branded 12AX7. Not only is V1 important, V3 is also key to most of the ice experienced in all channels. I understand the blanket though.

When I did run the Mark V90 as it was my only amp at the time, it was mostly with crunch as that was tolerable and sometimes I would favor the Mark I mode. Why you are having the issues when using the thick switch and with crunch is still a mystery. Since the tubes are hanging downward, I generally do not consider the presence of aluminum dust around the tube socket. If you have spent a lot of time removing the tube shields, there is a tendency for the friction between the tube shield and chassis to create aluminum dust that will fall to the PCB when the tubes are facing upward. This is more of an issue with amps like the Royal Atlantic or any of the Rectifier type than a Mark. I have had lost channels due to that or in most cases lost most of the tone. Once in a while, or after tube rolling those amps, I need to go through a cleaning process to remove any aluminum dust that may accumulate round the ceramic tube sockets. I doubt this is the issue you are having. I am just making note of it.

 

[user 83127]

I do recall reading that about mark thick. My v:90 is old that some of the writing has worn away but I’m sure it’s always full power but I may switch it down without thinking sometimes. It’s just that I noticed this is the only time channel 2 chatters (crunch with mark thick). I always have mark thick selected.

For now on I’m just using mark 1 on channel 2. It solves the problem for now and I discovered it sounds better than crunch any way, imo. I guess I used the crunch because it is a little louder in volume than mark 1 and better fit certain older rock songs. Like I said before my main channels are 3 mark 4 for and 1 fat. I only use 2 for a few select parts/songs.
But I don’t know, after playing with mark 1 it does have some great smooth lead and rhythm tones. I discovered my love for it through this ordeal.

Anyway this winter I might send it in just to have it checked out because it is over 13 years old.

If you haven't had someone tell you what your issue is...it sounds an awful lot like the footswitch, 12v rail problem....the issue is (mine went this way), the ground in the footswitch is ****...it is a screw dug into the baseplate of the controller chassis (yes...DUG INTO>>>>just force fit between the board...a LONG SCREW if you believe it...pushed into the chassis....)...fix this issue (maybe with a wire and for safeties sake reflow the whole board) and then go into the amp and fix the 4 diodes that are blowing because of the footswitch...they are on the 12v rail and there is a technical bulletin from Mesa on how to fix it(basic soldering skills is all are needed).

 

[tmg]

If you haven't had someone tell you what your issue is...it sounds an awful lot like the footswitch, 12v rail problem....the issue is (mine went this way), the ground in the footswitch is ****...it is a screw dug into the baseplate of the controller chassis (yes...DUG INTO>>>>just force fit between the board...a LONG SCREW if you believe it...pushed into the chassis....)...fix this issue (maybe with a wire and for safeties sake reflow the whole board) and then go into the amp and fix the 4 diodes that are blowing because of the footswitch...they are on the 12v rail and there is a technical bulletin from Mesa on how to fix it(basic soldering skills is all are needed).

Im that that good at soldering, really not at all. But I don’t even have the Mesa footswitch connected now. Im only using the fcb1010 and g major to switch channels and it still does it (only in crunch mode). In the past, the only reason I used the Mesa footswitch was to mute the amp while switching guitars.

 

[bandit2013]

Send an email to Mesa Customer service and describe what you are experiencing with the crunch mode. It could be a number of things with the amp. I highly doubt it is preamp tube related. Mesa should be able to respond with something. I would also include the serial number and year it was manufactured in your email. That is probably the best way to get this issue resolved or identified. I hope you get the problem fixed. It is no fun when an amp is not working.