TRS-80 Fireworks

Marvin Johnston marvin at
Wed Aug 28 08:34:15 CDT 2019

Thanks everyone for the feedback... I had no idea. I'll be putting in an 
order today with Digi-key (P/N 399-7483-ND) for probably around 25+ caps 
or so since I have at least that many TRS-80 2s, 3s, 4s.

I guess my only question is are there other similar caps that also need 
to be replaced? I'm well aware of the electrolytics and have that 
project on the back burner right now (about 10 Model 100s to repair.) It 
is nice that they are pretty trivial to replace!


On 8/28/2019 5:34 AM, Ethan Dicks wrote:
> 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.
> -ethan

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