choosing the right capacitors for retro systems and CRTs?

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jd213
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Location: Pennsylvania

choosing the right capacitors for retro systems and CRTs?

Post by jd213 »

Shopping on Digikey for capacitors is a bit confusing for a n00b/non-engineer like me. Have been choosing reliable brands like Nichicon and Panasonic, but should I always use capacitors rated for 105C degrees, unless the removed capacitor was rated for 85 degrees? Does it matter if the component is unlikely to get very hot? And why do some capacitors have ohm ratings? Should I only get ones without ohm ratings? Does it matter?

TLDR background info for those interested:

Have been recapping some old SFC consoles I got in junk bins in Japan recently as soldering practice. I find soldering and recapping to be rather satisfying (at least more than building and painting model kits, which I can never seem to get good at, despite doing on and off for most of my life). Not interested in starting a repair business or anything, but would like to get good enough to recap and/or repair my own retro consoles and CRT monitors.

One thing I haven't seen mentioned in the YouTube videos I've seen: DON'T try removing solder on surface mounted capacitor pads with a desoldering gun or solder braid/wick, unless you're experienced enough. Have already lifted several solder pads, but now I just gently twist off capacitors, then use a soldering iron to gently push off any remaining capacitor legs, and re-flow and add new solder, without worrying about removing all of the old solder.

Unfortunately didn't realize this before replacing the capacitors on a dead Game Gear. I lifted a couple pads with my desoldering iron, I thought I was able to re-trace and re-route the new capacitors, but it now powers on, screen turns on, then the whole system immediately turns off. Maybe something besides the capacitors was wrong with it, dunno. Oh well, it was fairly cheap, hopefully someone will be able to get some use of it in the future if I can't.
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buttersoft
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Re: choosing the right capacitors for retro systems and CRTs

Post by buttersoft »

An electrolytic capacitor comes with a published lifespan at operating temp. So, 2000hrs at 85degC, for example. As a rule of thumb, each ten degrees you lower that operating temp doubles the operating lifespan. Or so i've heard it said. So, if you can't find nice long-life caps, try going higher temp ones instead for the same application.

As for Ohm ratings - look up ESR. It does matter to a point, mostly for high-end audio applications.
jd213
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Joined: Mon Feb 01, 2016 9:03 am
Location: Pennsylvania

Re: choosing the right capacitors for retro systems and CRTs

Post by jd213 »

Thanks for the info. So it's fine to replace an 85C cap with an 105C cap, then?

Noticed that the big 1000mh cap in Super Famicoms is rated 85C, despite being under the heat sink. The replacement I got is also 85C, but they're quite a bit bigger (Nichicon Muse, probably overkill) so I needed to bend the legs and put it in sideways in order for it to fit under the heat sink.

Had a good time replacing the caps in an old yellowed SFC last night, it had some leaky caps but replacing all of them (including non-leaky ones) didn't fix the audio issue it was having: crackly sound at first, then the audio soon stopped outputting completely. At least I didn't make it worse. Maybe the SPDIF mod will still work, but if not then I'll save it for parts.
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Guspaz
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Re: choosing the right capacitors for retro systems and CRTs

Post by Guspaz »

This might be of interest, a tier list of capacitor brands: https://www.tomshardware.com/reviews/po ... 193-5.html
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TooBeaucoup
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Re: choosing the right capacitors for retro systems and CRTs

Post by TooBeaucoup »

If you want to eliminate all of the guess work, http://www.console5.com sells already finished high-quality capacitor kits for every console under the sun which have been tested in their respective consoles and checked for fitment so you know you're getting proper physical sizes as well.

However, if you'd rather just piece your own sets together, yeah, I'd just look for caps that equal or exceed specs of the caps to be replaced. Make sure temp tolerance is the same or higher. Always make sure voltage is the same or higher. Never replace a capacitor with a lower voltage than the original, but you can safely use a higher voltage capacitor. And you should always match capacitance ie, replace a 4700uF with a 4700uF. Those are the basics, but keep in mind there are other minor spec differences that won't necessarily hurt your equipment, but could make it not work the best.

For example, I swapped out a capacitor in a Sega Saturn power supply that had died and I used a spare new capacitor that I had lying around, which had proper matching specs for the capacitor I was replacing and while the power supply worked fine, after about 20 minutes of playing and the power supply warming up, I would get vertical wavy lines on my Saturn picture because something more minor on the capacitor obviously didn't match up with the old one. I got an proper Saturn capacitor kit from console5.com, took out my capacitor and the wavy lines went away and it now functions like normal. Just something to keep in mind. Just because you match up all of the capacitor specs when you shop for your own, your equipment still may not behave properly. That's why I like console5. All of their kits have been thoroughly tested in their respective consoles.

Here is a nice link that's pretty beginner-friendly and easy to understand.

https://www.electronics-tutorials.ws/ca ... cap_3.html
jd213
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Joined: Mon Feb 01, 2016 9:03 am
Location: Pennsylvania

Re: choosing the right capacitors for retro systems and CRTs

Post by jd213 »

Thanks, I have a Turbo Duo cap kit from Console5 that I soon hope to install in PCE Duo (still working last I checked, but I assume it's only a matter of time before its caps start leaking). I'm probably good enough to handle it, and the PCE Duo only cost like 8000 yen ($75), but I'm still a bit paranoid about messing up something that's a bit harder to replace than a 500 yen SFC from Hard Off.

Will definitely be ordering a bunch of Console5 kits the next time I visit the states.
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