DIY Audio guys or gals... Would you change these Caps?

[sc_rufctr]

I was changing out the fuses in my old school stereo amp and I noticed the caps seem to be leaking.

Would you change these out? Some people argue that if they're working, you should leave them alone.
I haven't recapped an amp before but I am handy with a soldering iron. I've built various advanced kits in the past. (Power supplies and phone pre-amps etc.)

Also... Rather than replace them with cheap Chinese ones that may not be legit what would you recommend?
I don't mind spending a bit extra so I wont have to redo this at some point.

There are 4 total and condition wise they all look very similar. Note the slight doming of the top and the dark yellow shmoo at the bottom.

[javadog]

I would replace them. I have no idea where to get good quality capacitors, though.

[MRM]

The best capacitors in the world are manufactured by Vishay. https://www.vishay.com They’re originally a German company but I think their headquarters is now in Belgium for tax reasons. Technically they’re a US corporation so that they can trade in the NYSE. They manufacture their product in Europe and Israel. Interesting company that is really dedicated to its products. They sell through distributors so you should be able to call any electronics warehouse and get what you need. They’re an old client of mine.

[dad911]

I order from Digikey or Mouser.

Sure they are leaking? Looks like glue at the base.

[LWJ]

I have replaced shorted caps in guitar amps. Why? No sound. No visual cues as to failure.

You may have some glue on the bottom.

Can you hear any shortcomings? Is schmoo your only evidence?

I would be hesitant.

I tried to remove some specs from my theater projector last year. Have a new projector now.

Be cautious.

[kach22i]

I was under the impression that resistors go long before most caps do, and leaking capacitors are a product of the old paper and oil ones that sound great but have limited life.

Most other caps don't leak as I understand it, they just stop working properly, with the so-called noisy cap syndrome followed by complete failure.

That could be glue as dad911 questioned, I suggest getting the opinion from a wider audience at a forum I used to post at.

https://www.diyaudio.com/forums/index.php

That said I had new caps put in my old Dynaco solid state amp and it sounded better than before. My experience is bad caps degrade the quality (slightly) then the music stops altogether.

[sc_rufctr]

Thanks for the input.

Originally Posted by LWJ

I have replaced shorted caps in guitar amps. Why? No sound. No visual cues as to failure.

You may have some glue on the bottom.

Can you hear any shortcomings? Is schmoo your only evidence?

I would be hesitant.

I tried to remove some specs from my theater projector last year. Have a new projector now.

Be cautious.

It may be glue but I don't think so. The top of the caps are slightly bulged. Other than that the amp is working fine.
I connected a Bluetooth adapter and it blew both output fuses. Serves me right for insulting the amp with a digital device.

I think it would be best to take it to someone who can tell me for sure.
There's an old guy in a hifi shop that I've know for years. He'd know but he's on the other side of town.

[sc_rufctr]

The amp's about 17 years old FWTW.

[908/930]

That looks like glue to me, is it all the way around? Can you take a pic of the entire circuit board. If the amp sounds ok I would leave it, unless you really want to modify.

[Gogar]

+1 that's just glue holding it to the board.

Those look fine. When they bulge - you'll know, don't worry.

[javadog]

He said they were bulging on the top slightly, hard to tell from his photo...

[aschen]

yeah I think those are OK, they are dc rail filter caps I think. You would hear some buzzing if they were totally gone

In my experience the life of these things are considerably more than 17 years typically.

[Gogar]

Originally Posted by javadog

He said they were bulging on the top slightly, hard to tell from his photo...

Right; my suggestion is that 'that ain't bulging, THIS is bulging." etc.

[T77911S]

glue.
it does not hurt to replace them.
they can make things noisy.
i would turn up the volume with nothing plugged in and listen before and after just to see if it does anything.

if you really want to get into the sound start looking at replacing signal caps.

[Rusty Heap]

[QUOTE=sc_rufctr;1040878



It may be glue but I don't think so. The top of the caps are slightly bulged. Other than that the amp is working fine.
.[/QUOTE]



ummm. what was your question again? Why are fixing what is not broke?

these 10,000 uF - micro Farrads caps are simple.......its a large absorber, a ripple absorber.

IF it ain't broke, you're just tinkering over-anallyy over thinking this.




Reading between the lines.........you popped two fuses......output fuses I assume.


Don't blame the amp, blame the user with blue-tooth adapter-a-crapter in hand


Once again you can OVERdrive components.


Paper filled caps when exploding are very cool......like a Pinata` or Confetti phluffs.






'

[RWebb]

you cannot blame the amp, but you can sometimes blame the caps

https://en.wikipedia.org/wiki/Capacitor_plague

[Jeff Hail]

Originally Posted by sc_rufctr

I was changing out the fuses in my old school stereo amp and I noticed the caps seem to be leaking.

Would you change these out? Some people argue that if they're working, you should leave them alone.
I haven't recapped an amp before but I am handy with a soldering iron. I've built various advanced kits in the past. (Power supplies and phone pre-amps etc.)

Also... Rather than replace them with cheap Chinese ones that may not be legit what would you recommend?
I don't mind spending a bit extra so I wont have to redo this at some point.

There are 4 total and condition wise they all look very similar. Note the slight doming of the top and the dark yellow shmoo at the bottom.

I repair guitar amplifiers.

If the capacitors are older than 15 years they are 100% done. Normal usage for even 10 years they are done. Electrolytic caps have a service life for use. They also have a shelf life for non use which is very short. Guitar amps, tube amps, solid state HiFi, all considered wearable components. Easy to test, just see how much voltage they are storing when the unit is turned off. Even if they have a bleed resistor they will store some voltage.

Be cautious as stored voltage in a 50v cap can stop your heart. Do some homework on safely discharging them. You can make a discharge tool for about $2 yourself using a 5 or 10k ohm resistor and some leads. You can also discharge caps with a multimeter but risk blowing the internal fuse.

Do you ever get ghost notes, strange harmonics or has the equipment lost its brightness in sound. Bass sound deadened or muffled? Caps are done.

That may be glue at the bottom for vibration control. Using a toothpick is it hard or gooey? Gooey they are leaking. Do they smell like electronics? Get your nose down there. The plastic wrap paper at the top shoulder is showing signs of transparency (delamination from swelling). Your existing Topcon caps are about the cheapest Chinese Aluminum Electrolytics on the planet.

Take our time removing the old ones. If you can try to cut the leads on the cap side of the pcb. It will leave little stubs you can solder to versus desoldering on the backside and having the traces lift off the pcb which is a headache to repair.


F&T and SoZo are top brands for caps. They make a lot of mil-spec components. Vishay is excellent also. These three are considered the best in the industry. 4 high quality caps should run you no more than than $20 in parts.

I get my parts from Amplified Parts. They are fast to ship and carry a large inventory. Electronic components may be limited to shipping in country because of restrictions. Might want to find a local place on your side of the hemisphere.

https://www.amplifiedparts.com/