The Boogie Board

Discussion Forum for Mesa Boogie Products
It is currently Tue Jul 25, 2017 3:50 am

All times are UTC - 6 hours [ DST ]




Post new topic Reply to topic  [ 4 posts ] 
Author Message
PostPosted: Wed Jun 28, 2017 3:56 pm 
Offline
Bottle Rocket

Joined: Wed Jun 28, 2017 3:40 pm
Posts: 1
Hello -

My Roadster head has static on channel two, much like a bad tube or dirty socket. I have already replaced preamp, power, and rectifier tubes, and cleaned sockets.

I've narrowed the presence of symptoms down to being heard only when low, mid, and high controls are turned up on channel 2. When those are turned all the way down, the problem disappears, even if I have gain, master, and presence all the way up. The static sound is unique to channel 2, which initially prompted me to change the preamp tube. The problem is worse on Brit and Fat modes. I see that Channels 1 and 2 use V2A for gain stages, but I haven't noticed the problem in channel one across any of its modes.

Any input would be appreciated. I've looked through the forum before posting and haven't found a topic that was specific to this issue. Thank you in advance.


Top
 Profile  
 
PostPosted: Fri Jun 30, 2017 5:59 am 
Offline
Dual Recto

Joined: Fri Feb 22, 2013 7:31 am
Posts: 2145
Location: North Carolina
Here is a suggestion..... I have had this issue with my RA100 but the symptom got worse and lost bass and midrange. It is more common with amps that have the tubes facing upward.... Aluminum chassis and the aluminum tube shields do not make for an ideal combination if you change tubes often.

You may have to remove the chassis to inspect, also you need to remove all of the tube shields and preamp tubes. Use a flashlight and look into the holes where the tubes go and inspect around the tube sockets. You may see aluminum dust on the PCB. This in itself may lead to other issues, tone loss, etc. and if there is enough conductive material present may even cause a short.

Remedy: Q-tip dipped in weak acetone (nail polish remover, do not use the strong stuff you get in a can or the type with the oil in it) use the moist Q-tip to pick up the fragments, try not to swirl around too much. The acetone will evaporate without leaving a residue. Once you have cleaned up the larger pieces, use compressed air to blow off the rest. This may fix your issue.

Before you install the tube shields, remove the o-ring and clean them. They are supposed to be black in color, not gray. I generally use an liquid automotive wax (liquid ice) which is good for synthetic rubber too. ( I used it to clean my guitar bodies and to dust off the amp tolex). You will notice the tube shields will go on very easy after the rubber O-rings are clean (note that the liquid nano wax is more like an oil than a wax).

While you have the amp chassis out, you may as well check all of the ribbon cables. Move them off the terminals and reseat them (take one end off and put it back on). Use caution as the power supply capacitors may have dangerous levels of charge remaining on them. Best way to discharge the caps and other storage areas on the PCB. unplug the amp from any outlet, remove the AC line cord. Place the standby switch to off as if you were going to play though the amp as this will connect the power supply to the rest of the circuits. ( if you cannot remove the AC line cord, just keep it unplugged from any wall outlet). Give it a day or so and the power supply will have discharged if there is any stored energy. Most of the Mesa amps have bleed resistors across the capacitors but if they are not intact, the standby trick works.

Hope this helps. Note: if you are going to use compressed air to blow off the aluminum chips or dust, best to remove the chassis as this will allow the air to escape with the dust.

_________________
Current amps:
TC-50, JP-2C, MK V, Roadster, RA100
Old friends I sometimes miss:
Mk III (blue stripe), Mark IVb-WB


Top
 Profile  
 
PostPosted: Fri Jun 30, 2017 11:09 am 
Offline
Mark II

Joined: Wed Aug 04, 2010 10:32 am
Posts: 83
Location: New Jersey, USA
Compressed air is your friend. Take it outside to avoid getting debris all over the place.

_________________
Guitars: Hamers, Heritages, G&L Legacies, EBMM Steve Morse, Carvin Bolt, Fender Tele
Amps: DC-5 1x12 w/Master Volume + EFX Mods, Maverick 2x12


Top
 Profile  
 
PostPosted: Fri Jun 30, 2017 4:53 pm 
Offline
Dual Recto

Joined: Fri Feb 22, 2013 7:31 am
Posts: 2145
Location: North Carolina
I forgot this..... if the static is continuous or seems to pop up at random at any time it could be something tube or amp related.....However, if it seems to occur when the air conditioner is running it may be power line related caused by external sources that share the same AC line or power feed from the outside transformer.


I get a few crackles or pops with most of my amps and usually on the clean channel when I notice it most, but it seems to only occur when the air conditioner is running. If and when I will be recording I either will set the thermostat at a setting that will never get satisfied so I do not get the electrical noise when the unit cycles on and off.

_________________
Current amps:
TC-50, JP-2C, MK V, Roadster, RA100
Old friends I sometimes miss:
Mk III (blue stripe), Mark IVb-WB


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 4 posts ] 

All times are UTC - 6 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 4 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group