'Cap Job' Help

[Rawlins]

Hey Guys and Gals,

I've been thinking about replacing all the caps in my Fender Blues Deville 2x12 but I cant find any information about it. All I can find is 'replace the caps'. They never say which ones, or with what.

If I look on the schematic at C1, it says 22uf 25V, so do I need to find a cap of that spec, or is there something else to it?

Also, do I change the filter caps as well? I assumed I change ALL electrolytics, and JUST electrolytics, not film or foil?

Last thing, whats the best type/make to use? :confused:

Thanks, Ben

[mageerc]

Unless your amp is over 10 years old, there more than likely is no need to replace the electrolytic capacitors. If you do choose to do it anyway, replace all the electrolytics... the filter caps, cathode bypass caps and bias cap with similar values and voltages of the originals.

[John Phillips]

Unless the amp is over 20 years old - which no Blues or Hotrod series amp is - or there is some evidence of premature failure, you don't need to change the caps.

20 years is a conservative low estimate too, most amps up to 30 or even 40 years old still have their originals, and caps weren't as durable back then either. No, it's not a good idea to leave them in indefinitely, but I wouldn't even consider changing caps routinely in any amp made before the early to mid 80s unless there was a good reason to do so.

My rough rule of thumb is:

Under 20 years old - don't change caps unless they've failed.
20-30 years old - change caps if you're doing other major work that warrants spending a small amount extra to make the amp 'new again' (eg extensive mods).
30-40 years old - change caps if you're doing any other work at all.
40+ years old - change caps even if nothing else needs doing.