Caps need replacing? (photo)

[JDJ]

I've heard that the caps need replacing when they become "pregnant". Based on the source-date codes, they are 42 years old. However, the amp sounds excellent. Here's a photo:

http://i84.photobucket.com/albums/k36/j616129/BF%20Pro%20Reverb/December2007049.jpg

Despite the age, do they need replacing even though the amp sounds fine?

Am I courting danger (fried tranny) by waiting?

What make and model of caps would you recommend replacing them with?

Will new caps change the tone of the amp? How so?

Thanks! :)

[mageerc]

Yes, they need to be replaced... they are starting to rupture and will soon start leaking. You may think the amps sounds good, but after the replacement you will notice an improvement in the bass response. When those thing rupture, they make a mess and in some cases, they actually explode!

[HipKitty]

Yup! They gotta go!

[doveman]

Ditto ...

But these caps can kill you ... even after unplugged for a while. Do some research on how to dissipate the voltage before you grab one. You probably know this ... but just wanted to mention.

[slider313]

And I'm sure the one in the bias supply is original also. That one should be changed as well. You may as well change all the electrolytics and test your coupling and tone caps for leaks also.

[JDJ]

What make and model of caps would you recommend replacing them with?

[slider313]

I would use Sprague Atoms.

[mwm523]

I would use Sprague Atoms.

+1 :)

Like these, just use values that match what you have now.
http://i145.photobucket.com/albums/r219/mwm523/caps_sm.jpg

[WaltC]

The PC answer is Sprague Atom, they're good and will work well.

The not-so-PC answer is any good electrolytic rated to handle the voltages present. Get ones that are close in value to the first two 70mF/350V, and the (looks like) 20mF/550V other three. Keep the micro-Farad rating close to the stock ones and try and get the voltage ratings *at least* as high as the stock ones. Make sure all the caps are rated to perform up to 85 degrees C, and upgrading to the 105 degree caps isn't too expensive and they tend to be more stable and dependable in my experience.

Remember you will be dealing with 500+ DC volts on these caps and they can "recharge themselves" even when the amp isn't plugged in, and if any of the above terminology seems "greek" to you, then you probably ought to consider taking the amp to a good tech to get the job done. No amp is worth stopping your heart over <G>.

[JDJ]

Mike Clark has agreed to service the amp. I will be in watchful attendance. Thanks for the input.

[twinrider1]

Edumicate me. What should I be looking at in the pic? Is it the area along the length where it looks like it's soaking through the paper? Or the nippley bulges on the end caps of the orange caps?

Thanks!

[mwm523]

Edumicate me. What should I be looking at in the pic? Is it the area along the length where it looks like it's soaking through the paper? Or the nippley bulges on the end caps of the orange caps?

Thanks!

The bulges.

I think those marks on top are from the foam strip on the underside of the metal cover that goes over them.

[slider313]

The bubbles at the end of the caps. I've seen them burst and the white electrolyte powder spews all over the cap can. I've also seen them pop and burn leaving black burn marks.

[JJGross]

Any cap with those Witchypoo Warts growing out of the ends is not something you want to trust for very long. Internally, it's already ruptured and won't take long to go external as well. I'm not sure about the wet looking stains, but I've never seen that in new caps so my guess is that it's just another nail in the coffin unless it's something like glue or shellac that was put (or dripped) on the outside for some reason. To me it looks like it's coming through from the guts - not good would be my very non-expert opinion.

Cheers

[The Pup]

Although not a popular answer...I've seen bulging caps that still performed fine and were left alone (going on 30 years) without any issues.

But I agree with most, I use amps for playing...not collecting. When in doubt, recap and get on with playing!

[mark norwine]

Although not a popular answer...I've seen bulging caps that still performed fine and were left alone (going on 30 years) without any issues.

As have I...........I've seen this, too:

http://i86.photobucket.com/albums/k105/mark_norwine/bad_cap.jpg


My vote would be to change them......

It's all part of the "care & feeding responsibility" that one takes on when one buys a tube amp....

[John Phillips]

Change them.

The PC answer is Sprague Atom, they're good and will work well.

The not-so-PC answer is any good electrolytic rated to handle the voltages present. Get ones that are close in value to the first two 70mF/350V, and the (looks like) 20mF/550V other three. Keep the micro-Farad rating close to the stock ones and try and get the voltage ratings *at least* as high as the stock ones. Make sure all the caps are rated to perform up to 85 degrees C, and upgrading to the 105 degree caps isn't too expensive and they tend to be more stable and dependable in my experience.

Remember you will be dealing with 500+ DC volts on these caps and they can "recharge themselves" even when the amp isn't plugged in, and if any of the above terminology seems "greek" to you, then you probably ought to consider taking the amp to a good tech to get the job done. No amp is worth stopping your heart over <G>.+100% on everything there.

FWIW, if one goes the way of the one in Mark's pic, you'll get a shock (non-electrical) which could induce heart failure anyway - like a very loud firecracker going off inside your amp with no warning.

It's not even funny when you're expecting it - it's happened to me several times when powering up old amps that hadn't been used in a while, and I didn't want to change the caps first until I'd found out what/if other work needed doing, or whether the caps could possibly be saved (it matters to some owners, irrespective of whether it's sensible).

[JJman]

Even if they looked perfect, it's time to change them.