I would suggest that anyone needing advice on what equipment and supplies they need shouldn’t be doing this as a side hustle!

If you really want to get proficient at it then watch some good YouTubers that focus on fixing/refurbishing retro hardware and you’ll get a good idea of the techniques and kit needed. Think Adrian’s Digital Basement, Necroware, BuB, etc.

But as a start for kit:

Soldering Iron (decent quality)
Leaded solder
Flux
Desoldering braid/wick
Desoldering gun (you might get away with a manual pump, but I hate the things)
Helping hands/something to hold smaller boards/parts

If you end up going deeper down the rabbit hole repairing more than just failed through-hole caps you might need additional stuff like:

Conformal coating
Different gauges of wire for trace repairs
Hot air station
Kapton tape
Oscilloscope

paradigital wrote on 2024-04-10, 21:39:

Helping hands/something to hold smaller boards/parts

A board holder is one of the best pieces of equipment I've bought. Holds a full-sized MB and makes de-soldering so much simpler.

Lylat1an wrote on 2024-04-10, 19:34:

I'm considering replacing capacitors on old hardware as a side-gig, but I haven't done it before.

Aside from my inexpensive multi-meter and adjustable soldering iron, will I need any other equipment?

For cap. replacement or other similar level of repairs I'd recommend the following:

Component replacement & Testing:

Adjustable temperature Soldering iron - basic chisel tip is fine for most work
Fume extractor
De-soldering gun - if you plan on doing a lot of recapping, highly recommended getting a proper de-soldering gun
Leaded solder + flux
Multimeter
ESR meter
Pliers
Fine-tipped tweezers
Flush cutters
Kapton (heat resistant) tape
Board holders / Vises - I really love the PanaVise board holder; great for recapping motherboards (see previous post)
POST Diagnostics card

Misc equipment (cleaning, corrosion removal):

Basic magnifier for inspection
Burnishing tools and/or Dremel with various sanding and polishing tips - good for corrosion removal
Disassembly tools (screw driver kit, prying tools)
Cotton Swaps, Paper towels
Solvents (IPA, Deoxit)
Anti-static brushes

Storage, etc:

Storage bins
Tool storage - shelves, pegboard, bins, drawers, etc.
Personal protective equipment - gloves, mask, especially if using chemical solvents and glues
Good lighting and power outlets
Workbench with a descent surface to work on

Also, are there any tutorials on the subject that you guys would recommend?

Mr. Solder Fix is my favorite YouTube channels for solder repair videos: https://www.youtube.com/@mrsolderfix3996

As you mention you haven't done this before, you're going to want to get in a lot of practice before trying to make this a side-gig.

And if you haven't done so, research different capacitor types, markings, what types of caps can be substituted and when it may be advantageous to do so (e.g. polymer instead of electrolytic), etc.

Random stuff everyone forgets...
Nurse on standby with sterile IV lines and 12 quarts of crossmatched sanity.
Monthly subscription to Capacitor Connoisseur loot box.
Eye protection.
Eye enhancement.
Eye drops.
Igor ... (to appear at your elbow with a "Yeth Marthter" and spare braid, flux, forceps, scalpel, chainsaw etc in a timely fashion)
Acetylene torch for when the groundplanes are really being a bastard.
Magnetic pickup, to poke components around on the floor before remembering aluminum and copper aren't magnetic and you're going to have to bend down anyway.
burn cream.
liquid skin.

Thanks to all who have responded so far:

I'm well aware that I'll need experience before I can profit from this; but we all have to start somewhere, and I figured asking here would be a good start.

I was absolutely butchering stuff before I got a desoldering gun. Get a desoldering gun.

Also shell out for a quality desoldering iron. I absolutely love hakko and my hakko is the best soldering iron I’ve ever used, you can’t go wrong with a hakko, but make sure whatever you get costs 100+ and is from a legitimate serious company that’s been around for a long time.

Fluke multimeter, esr meter, oscilloscope, ipa, flux, standard tools, microscope (these are not scientific microscopes but have two eye pieces and a kind of metal stand that holds them above the table), isolated transformer. If you can’t afford these then you’re not ready to have people pay you for your work.

If you are going to make this kind of stuff as a business, you better be proficient about it because otherwise you may just end up screwing up people’s equipment. I’ve personally repaired and recapped all kinds of stuff for many years and I think I’m generally relatively skillful at it at least in hobbyist standards, but I still don’t do this kind of work for other people. I’ve been asked for a few times, but always said that I do this sort of work only on stuff I own personally. There are some risks always involved even with the easiest imaginable job.

And if you are talking about changing caps, you better learn to do it for all types of vintage electronics which include two layer boards with through hole caps (easiest), multi layer boards with through hole caps and SMD caps. For example multi layered boards are much more difficult to work with and if you screw up one via, board may be irrepairable.

As you apparently have no experience at all, I wouldn’t even think about doing this kind of work for others yet for a long time. Also, just making recapping probably won’t be that good side job and to make any money after your investments in equipment, you probably want to make all kinds of repairs. Recapping is one of the easiest tasks at least for simple two layer boards with through hole caps, but actually diagnosing faults and making all sorts of repairs would turn out much more profitable. Of course you also need more equipment and skills to use them like heat plates, oscilloscopes, reballing and so on. And if you really want to make money out of repairing stuff, you probably want to do modern stuff such as gaming consoles and so on. Retro market is quite niche after all.

If I were you and I’d wanted to do something like this (which I don’t), I’d get all the equipment needed (and all of them quality stuff!) and start purchasing stuff that needs recapping and do the work on them. If workmanship looks good and it works as intended, then I’d put that item for sale on ebay or local equivalent. In this way there would be no risk of breaking other people’s stuff and you also would get some starting point to making money out of this kind of work.