TRS-80 Fireworks

Dave Wade dave.g4ugm at
Thu Aug 29 04:25:41 CDT 2019

 As I am sure others will say, I believe that the problem with the "X" filter caps is that the case becomes cracked and you get moisture ingress....

> -----Original Message-----
> From: cctalk <cctalk-bounces at> On Behalf Of Kevin Parker via
> cctalk
> Sent: 28 August 2019 23:51
> To: 'Marvin Johnston' <marvin at>; 'General Discussion: On-Topic and
> Off-Topic Posts' <cctalk at>
> Subject: RE: TRS-80 Fireworks
> Quite normal - the capacitors dry out after about 30 or  40 years - there's lots
> of info around on replacing them with a polymer capacitor. I have over 20 TRS-
> 80's with a large contingent of Model 3, 4, 4Ps, 12 and 16s - all had the same
> issue so if I acquire one now I do a pre-emptive strike before powering up.
> Kevin Parker
> 0418 815 527
> -----Original Message-----
> From: cctalk <cctalk-bounces at> On Behalf Of Marvin Johnston
> via cctalk
> Sent: Wednesday, 28 August 2019 6:16 PM
> To: ClassicCmp <cctalk at>
> Subject: TRS-80 Fireworks
> 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?
> So far, I've gotten the fireworks in two out of two TRS-80s (model 3 and
> 4) when they were powered up. In both cases, the problem was with the main
> line filter capacitor mounted on one of the power supplies. The computers
> continued to work which was my first clue the problem was not serious :).
> 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.

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