TRS-80 Fireworks

Peter Cetinski pete at
Wed Aug 28 06:35:06 CDT 2019

> On Aug 28, 2019, at 4:15 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?
> 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.

This is well known issue on all Models of TRS-80, except the Model I.  In fact, it is almost guaranteed that your power supply main Rifa filter capacitor will blow within a few minutes of when you first power up one of these TRS-80s after sitting for years if you have the original caps.  So much so that I was able to record one fail in spectacular fashion. <>

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