# Cap replacement question



## Dan Caldwell (Feb 26, 2017)

So I just got a 67 Fender Bassman and it sounds great but having a few issues with noise. Might be a tube/dirty issue (white noise that comes on suddenly and I figured out disappears with a bit of a smack on the amp) but also thinking caps might need replace.
Question is if you don’t replace caps, and they need to be, is it bad for the amp at all?

Im not versed in the technical stuff (I’d get an amp tech to do the work) but I’ll play with tube swaps and deoxit and see if that fixes it Just wondered it I shouldn’t play it until it’s fixed.
Any input is helpful.
Thanks,

Dan


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## jb welder (Sep 14, 2010)

I'd wager the tube sockets need cleaning.
Generally caps that go bad just make more hum and no damage is done. In rare instances they can short and burn a resistor, or in very rare cases burn out a power transformer. The fuse should prevent that from happening but there are always exceptions to rules.
A failed cap in the bias circuit could also result in damaged power tubes.


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## Budda (May 29, 2007)

If it's never had the caps done, get 'em done. Hopefully the previous owner knows when the last service was.


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## Latole (Aug 11, 2020)

Tubes's plate resistors may make some noise after so many years. Replace them all. 

Second hand amp, alway check fuse to be sure it is the right one. Too powerful fuse may burn Power transformer in cas of output tubes failure.


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## Latole (Aug 11, 2020)

Question is if you don’t replace caps, and they need to be, is it bad for the amp at all?

Generaly speaking or short answer is no. I work on old vintages amps since 20 years and many of my customer want to keep them original and play them as is. Filter caps failure I see, make hum in the speakers, even a bias cap issue.

If you know a qualified tech, new filter caps will help your amp to sound better. Same time replace bias filter caps.
If you don't know qualified tech, stay away.
Alway ask for F&T or Sprague filter caps.à
Keep you old parts


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## Latole (Aug 11, 2020)

I will not claim that a more serious fault is impossible but by having the right fuse the amp should be protected.
New filter caps result in a tighter, faster response and less ghost notes.


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