Replacing Liquid Electrolytic Capacitors With Solid Capacitors

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Jagasian
Posts: 421
Joined: Wed Feb 09, 2005 9:31 am

Replacing Liquid Electrolytic Capacitors With Solid Capacitors

Post by Jagasian » Wed Jun 24, 2020 8:41 pm

The liquid electrolytic capacitors in electronic devices such as the SNES start to dry out after 15 years roughly. Some last longer than others before needing to be re-capped. Dry caps may also accelerate the aging of other components in the SNES, degrade audio and video quality, as well as cause other issues.

Since the release of the SNES, there have been advancements in capacitor technology, and so there are solid polymer and solid ceramic capacitors with high enough capacity to replace electrolytic capacitors in some situations.

There are two main benefits of these solid capacitors: they do not dry out and they have very excellent electrical noise filtering. So replacing the liquid caps with solid capacitors means you will never have to replace the capacitors ever again.

So I gave it a shot and it works great! Every liquid cap is replaced with a solid cap and it looks great when measures on my oscilloscope and my CRT TVs.

Below is a capacitor parts list and other pics showing the finished job. I used high quality capacitor brands (Panasonic and Kemet are in the same league as Nichicon and a small list of other top tier brands). The solid capacitors are rated for use up to 125 Celsius versus 105 Celsius used by the high grade liquid electrolytic caps that most people use when replacing caps.

Is this overkill? Yes, but if it means never having to replace caps again, it is worth it when you have dozens of consoles, many arcade PCBs, dozens of CRTs, and other old electronics. Replace with solid caps and never worry about it again.

One last note. Capacitor C67 that Nintendo used is rated for 25 volts, but the SNES power supply itself only uses a 16 volt rated capacitor and using my oscilloscope I confirmed that it is safe to use a 16 volt rated capacitor for C67 as the voltage at C67 never goes above 10 volts.
Parts list
Parts list
Ceramic capacitor replacement for C62
Ceramic capacitor replacement for C62
Solid polymer capacitors made by Panasonic
Solid polymer capacitors made by Panasonic
Voltage ripple on C62 before replacing caps
Voltage ripple on C62 before replacing caps
Ripple on C62 after replacing caps, notice less dip in the voltage
Ripple on C62 after replacing caps, notice less dip in the voltage

Jagasian
Posts: 421
Joined: Wed Feb 09, 2005 9:31 am

Re: Replacing Liquid Electrolytic Capacitors With Solid Capacitors

Post by Jagasian » Thu Jun 25, 2020 8:28 pm

Voltage regulator output before upgrades
Voltage regulator output before upgrades
Voltage regulator output after upgrades
Voltage regulator output after upgrades

calima
Posts: 1130
Joined: Tue Oct 06, 2015 10:16 am

Re: Replacing Liquid Electrolytic Capacitors With Solid Capacitors

Post by calima » Thu Jun 25, 2020 11:39 pm

Why recap the old voltage regulator instead of replace it entirely? I hear the modern replacements are quite a bit better.

lidnariq
Posts: 9418
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Location: Seattle

Re: Replacing Liquid Electrolytic Capacitors With Solid Capacitors

Post by lidnariq » Fri Jun 26, 2020 12:14 am

Modern switching regulators may not be a fantastic plan¹, and linear regulators haven't gotten much better in the past 30 years, and even an ideal regulator can't help with power demand that's too physically far away from the regulator output (because the feedback loop is at the regulator output).

¹ Krzysiobal has had some recent bad experiences with switching power supplies failing and taking out the irreplaceable parts of the Famicom at the same time.

For efficiency, a two-stage design (switcher for efficiency, followed by LDO for safety) might make sense. Maybe. Also, the SNES still uses the unregulated 10V all over the audio path.

Jagasian
Posts: 421
Joined: Wed Feb 09, 2005 9:31 am

Re: Replacing Liquid Electrolytic Capacitors With Solid Capacitors

Post by Jagasian » Fri Jun 26, 2020 1:42 pm

calima wrote:
Thu Jun 25, 2020 11:39 pm
Why recap the old voltage regulator instead of replace it entirely? I hear the modern replacements are quite a bit better.
Sorry if I wasn’t clear, but I replaced the voltage regulator with a modern higher rated regulator, in addition to upgrading the caps and adding the cap on the output of the new regulator.

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