Mark III, IV caps NEVER need to be replaced???

[droptrd]

Mine wasnt humming either. Just tons of hiss and other noise. After the recap, the amp is dead quite.

 

[okgb]

When i talked to Mike B , he said that the 3 psu caps on the main board
are not usually changed [ that leaves just the 4 on a separate board ]
My amp didn't hiss , just sounds like ****

 

[kdorsey]

I was a manufactures' rep for several capacitor companies back in the day, including one of the original sources for Mesa's electrolytics, Illinois Capacitor. I can tell you that after hundreds of highly critical design projects (military, audio, automotive, etc.), the one thing that always sits in the back of an engineer's mind is life (of the cap). The gel-like liquid inside these components can and will start to dry out over time. The speed at which this happens is relative to the environment in which they operate, but mostly relative to the formula of the electrolyte. Inexpensive SE Asian sources for 'lytics were infamous for stealing a competitor's recipes and duplicating it...until they figured out that they were missing the "secret" ingredient. This happened in the computer industry several years ago and many millions of computers prematurely failed as a result. Domestic makers, like IC, became a more trusted source. Their product just lasts longer. How long? Only Mesa can say for sure, but if you have quality components in your amp, they should last at least 10 years. Extended temp product could last longer, if you can find it. But I'd be hard pressed to prove that my 20+ yr old MkIII needs new caps.

Unless one starts to bulge or bursts, I'm not changing them. There's no need.

 

[Don]

Is the cap replacement unique to a few tube amp manufacturers or is it across the board over time?

It's accross the board. It's a cap issue, not an amp issue and it's the case with every brand of amp.

 

[K-Roll]

guys, could anyone recommend a good replacement with correct values for my MK4? I need 2 bias caps and 2 EQ caps. I've been looking around but cant seem to find a high quality replacement axial caps with values:

47uF 100V
220uF 63V (-in my mesa it says sprague, but it seems sprague no longer does these)


thanks for your help