pigtail new electrolytic across old removed one in PSU?

Most PC psu are too crowded to do anything fancy from the component side and there often isn't sufficient headroom to allow for added 'pigtail' detail on a suitably-rated replacement.

Just forcefully pulling the body of the cap, to separate from its leads (still soldered in the board) will reveal what is available to work with. The leads will break internally in the capacitor and the copper/Al bonding lug will be pulled through the rubber seal. Only the lead wire portion of the remeins will be solderable.

It's worthwhile going to the trouble of getting at the solder side. This will also allow testing of other aging caps that may not show obvious signs of catastrophic failure and ensure a proper solder joint on suitable or superior replacements.

Just keep track of the screws and mechanical details, as competent and careful reassembly is critical to later, safe operation. Hipot barriers should be retested on the completed reassembly, prior to re-use.

RL

If you can't unsolder 2 wires at a time, using a solder sucker, or desoldering braid, maybe flush cutting diagonal water cutters might work. They're narrow enough to fit under the electrolytic and allow you to cut both leads (one at a time). Then, you can unsolder each wire individually.

If you're going tool shopping, also buy some PCB liquid soldering flux (not plumbing flux), a solder sucker, 91% alcohol, flux brush, etc.

Thank you both, I have decided to remove the board, carefully do the discharges, and then proceed with a proper replacement. A question though: what recommended electrolytic type and brand, preferably something good enough that I won't have a repeat in a year. I have junk box electrolytics, but no way I'm going to use those. Thanks again.

Don't judge a book by its cover and don't estimate the lifetime of an aluminum electrolytic by its brand name. The operating life of the typical aluminum electrolytic capacitor found in a typical PC power supply is determined by the ripple current and operating temperature.

"Calculating the Operational Life of an Aluminum Electrolytic Capacitor"

Various manufacturers have online calculators for estimating the life:

One problem is that the calculators assume an appropriate product life, proper component selection, too low a voltage rating, and undersized capacitance (which increases ripple current and therefore self heating. If the design and component selection is by "cost reduction", with the goal being to minimize production cost at the expense of literally everything (including capacitor life), it will not matter what brand or value capacitor you use, the expected life will probably be low. If you want to play it safe, buy a capacitor that will fit in the PSU, use capacitance and voltage ratings that are the same as the original, and maybe buy a 105C rated capacitor instead of 85C. I can't provide specific numbers and specs for a likely capacitor because you did not provide a PSU maker and spec details on the capacitor you're replacing. If you had provided numbers, you would likely get better answers.

Incidentally, don't discount using your junk box electrolytics. You can test the capacitors using an ESR (equivalent series resistance) tester. The ESR value (in ohms) will give you a clue as to the "quality" of the capacitor.

Use one of these charts, preferably the one that comes with whatever tester you own, to determine if the capacitor can be used. Also, measure the capacitance and compare with the markings on the capacitor.

If you really want to dive deeply into the abyss, you can measure the ESR at different temperature extremes. Here's what I did:

Good luck.

Oops. If forgot to include a link to the capacitor charts:

Same size, voltage and temperature rating (or better).

Digikey delivers small packages for ~8$

RL

I would use Panasonic 105C capacitors from Digikey or Mouser.

Yes, I know, I just got off the phone with them. Very disappointed. For a hobbyist like me, they were ideal as I could mail in my order and save on shipping cost when I only needed a small handful of items. I'd print out their mail-in PDF and fill out the info then send check or m.o. When I couldn't find the form on their website this time around, I contacted them only to find out they did away with the mail-in option.

So the PC supply you're repairing is in 'the PC' you need to place an order on-line? Most public libraries will book time on their machines - and ISPs offer some kind of 'web-mail'.

List dimensions, values and destination in an e-mail and I'll send you a packet.

RL