Mesa MkIII issue

[thendrix]

I have a 1987 Mesa MkIII and lately I have had an issue with looseing the "balls" when I turn the standby off after taking a break. I don't loose volume. It's more of loosing bottom end to the point I turn the treble off and the bass wide open and it still has to much treble. Sometimes I can turn the standby back on for a few minutes and when I turn it off the amp goes back to normal. Please explain replies as I am new to this type of diagnosis and repair. Thanks.

Tyler

[Chuck H]

I don't think your amp needs repair. I think it needs maintenance. I don't know how old your power tubes are but they don't last forever. Also, the power supply filters are wear parts too. They last ten to twenty years generally before they start to lose performance. If your handy you can do it yourself and save some $$$. Mesa's usually have "Mesa" branded Sprague "Atom" capacitors in the power supply. You don't really need to shell out the $$ for Atom's though. I've used Atoms for a long time but lately they don't perform any better than more affordable brands. When/if you do a "cap job" it's best to replace all the electrolytic caps in the amp. So that would include the bias supply filters and any SS device power supply filters in your amp. A cap job, new power tubes, clean and re-tension tube sockets, jacks, switches and pots and a proper bias will probably have it performing again for you.

[thendrix]

Thanks Chuck. I was thinking power tubes but I guess there is a little more to it then I thought.