Mark III still has a problem

[Subby32]

So I have now changed all pre's to Tung Sol and power tubes to SED and replaced the 7 main filter caps with sprague and F&T parts which helped alot with the noise floor and tightness of the amp.
But there is still a very harsh ice pick quality to the tone that was never there before.
No matter what the settings are it is aweful, and im using an lp through new planet waves cables into an orange 4x12 that is as warm as possible.
What the hell can my problem possibly be????
This is driving me crazy, it sucks not to have a great amp sounding good

 

[disassembled]

What trouble shooting has been done on the amp besides replacing parts? You probably just need to send the amp to Mesa for a check up if things aren't allright.



Greg

 

[Boogiebabies]

Did you clean the jacks and pots?

Does it do it with the Graphic off?

I would also check your cathode caps for continuity. You may have a bad cathode cap causing a bit of errant noise. I'v seen some Boogies with all the cathode caps replaced.

 

[Subby32]

as far as cleaning jacks and pots should i just spray contact cleaner into the pots and jacks and turn them a bit until its all good?
Its a really harsh high treble buzz that is constantly there at high gain settings that def was not always there.

How can i go about checking cathode caps? Do i have to unsolder them from the circuit first? and also what should they read if they are in working condition?

Thanks for the replies guys
I hope it doesnt need to be shipped to CA that would break the bank

 

[Russ]

Do not spray into the jacks. You can spray a little on the pot but not into the jacks. Spray some on a plug and work it in and out a little. Then use a q-tip to get the gunk out. You should probably do it with the chassis out so you can see if you need to swab up any standing fluid.

 

[Restless Rocks]

On a MkIII the presence control is critical to dialing in your high end character. If you haven't already, try turning it to 1 and your treble control to 6 and rethink your settings little by little. Try another cable and or guitar too.

 

[Restless Rocks]

On a MkIII the presence control is critical to dialing in your high end character. If you haven't already, try turning it to 1 and your treble control to 6 and rethink your settings little by little. Try another cable and or guitar too. Certain preamp tubes and a fresh set of 6L6's (especially if you're using a celestion) can be very fizzy and toothy. That's why I like 5881's for their tapered highs and warmer sound.

 

[Subby32]

my presence is on zero.
even with my last set of pre amp tubes which still work good, same problem.

 

[Boogiebabies]

as far as cleaning jacks and pots should i just spray contact cleaner into the pots and jacks and turn them a bit until its all good?
Its a really harsh high treble buzz that is constantly there at high gain settings that def was not always there.

How can i go about checking cathode caps? Do i have to unsolder them from the circuit first? and also what should they read if they are in working condition?

Thanks for the replies guys
I hope it doesnt need to be shipped to CA that would break the bank

I would start with a meter set to continuity and see if I get a open beep on one of them. If you use Caig De-Oxit, it evaporates fast and leaves a very small layer of lubricant to keep the contacts from oxidizing. Even better is the De-Oxit 100%. The worst thing to worry about is putting a rang below the jacks when the spray finds a weep hole or drips off the outer contacts. If you dont spray it like a Gorilla you will be fine. Just a shot and a Q-Tip after a minute is not a bad idea.

I would not doubt what the other guys are saying. Try new speaker cables, guitar cables, power supply and totally get away from your routine. Also, you have to check if it does it with the EQ in and Reverb etc.

 

[Subby32]

finally got it fixed!
turns out it was dirty *** pots, those bastards...

but thankfully all is good now, and i can tell the cap job helped with the tightness/noise/harmonic content immensly!

also i can now turn the presence up to like 7 before i hear any fizz whereas before even on zero is was too harsh/bright
thanks for everyone's help and responses i appreciate it.

Next step:
boogiebabies i read about cleaning the springs in the reverb tank but on the mark iii how do i open that up? it seams permanently shut?
also any schematics or instructions on a DIY iiic+ mod? id hate to ship all the way to Cali. im only 19 and broke haha

-Chris

 

[Boogiebabies]

The tank is glued shut with rubber cement.
I would not bother unless you want to carefully pry it open and close it with rubber cement and 8 clamps.

No dice on the IIIC+ mod. PM Reeko83.