TRS-80 Fireworks

dwight dkelvey at
Wed Aug 28 08:16:02 CDT 2019

It was at the Maker Faire, 1 year ago, we had these caps blow on 2 Apple II's. One ran for less than an hour before going and the other ran for a day and the next day it also blew ( it was my Apple II ). It now lives without the capacitor.

From: cctalk <cctalk-bounces at> on behalf of Ethan Dicks via cctalk <cctalk at>
Sent: Wednesday, August 28, 2019 5:34 AM
To: Marvin Johnston <marvin at>; General Discussion: On-Topic and Off-Topic Posts <cctalk at>
Subject: Re: TRS-80 Fireworks

On Wed, Aug 28, 2019 at 4:16 AM Marvin Johnston via cctalk
<cctalk at> wrote:
> I'm just curious how many people have powered up their TRS-80 computers,
> and ended up with a bang and a room filled with smoke?

I've had identical experiences with Rifa caps as others here.  One
thing about them, you don't need to be powered on.  The caps are
usually on the hot side of the power switch.  I've had a MicroPDP-11
and a Commodore D9060 sizzle when plugged in but powered off.

> Is this a normal problem with these older computers? I'm used to seeing
> the electrolytics give problems, but this is the first time I've seen
> one of the X type line filter caps blow.

Rifa caps are notorious for reasons already described.

Found in a lot of 1980s gear, TRS-80, Commodore, DEC... Replace on sight.


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