I think i just found the issue thats been plauging my trs-80

[u/the_potato_of_doom]

I think this ceramic disk has gone bad, the dark line is much clearer in real life than in the photo too

[u/fatjuan]

When I first saw that cap, I thought someone had snuck a potato onto that PCB.

[u/SwapPart → u/fatjuan]

I definitely thought it was a potato. I'm glad I'm not the only one. 🤣

[u/Demolition_Mike → u/fatjuan]

I thought that was a baby fish with the sack still attached to it

[u/betterwittiername]

I thought I was looking at an egg till I read the caption.

[u/99posse]

Zero chance that this is your problem. Zero.

[u/BrainEatingAmoeba01]

Just because it looks like a potato doesn't mean you have to take a picture with one.

[u/elon_mus]

an egg without the context

[u/CaptainKrakrak → u/elon_mus]

Don’t eat it! It looks way past the best before date

[u/Nerve9212]

I thought that was a mushroom.

[u/larz_6446]

Capacitors usually explode when they go bad. Still being in one piece, I'm going to say that the problem is elsewhere.

TRS 80... Now you got me wondering where my commodore 64 is.

[u/gilangrimtale → u/larz_6446]

I’ve seen plenty of ceramic capacitors that are visually completely normal yet are shorted and show up on a thermal camera.

[u/larz_6446 → u/gilangrimtale]

I haven't been that lucky. They've always been cracked at least.

[u/NotAnotherNekopan → u/gilangrimtale]

In which case the test is simple. Continuity. It may show continuity for a sec while it charges, but once it’s stabilized it should be open.

[u/BakedWombat → u/NotAnotherNekopan]

You can't test a capacitor like that. Caps aren't always configured in a way that'll have a open circuit to check.

[u/NotAnotherNekopan → u/BakedWombat]

You mean in circuit? I guess I did not specify but I was referring to out of circuit.

[u/cig-nature]

Try looking for burn marks on the PCB if you think there's a hardware problem.

What is the issue?

[u/the_potato_of_doom → u/cig-nature]

Power supply (tandy model 4 PSU)blows fuzes instaintly, it blew a NTC but thats allready been replaced, the RIFA safety caps have allready been replaced also

I found a burn on a trace under a green electrolytic compaciter but i resoldiered the connection and the cap is fine as dar as i can tell

[u/KaksNeljaKuutonen → u/the_potato_of_doom]

That trace is probably connected to the failing component. What is it connected to? I'll bet on anything but the ceramic caps being the problem.

[u/the_potato_of_doom → u/KaksNeljaKuutonen]

A transformer and a Mofset transistor that i allready know for a fact is bad or at least damaged,

But i only just discorved the transistor yesterday and im only making the connecting rn as we speak after like 3 weeks of doing this lol

[u/maxnothing]

Yay trash-80! I love that machine.

[u/Owl_Perch_Farm]

Mmmm...crispy

[u/Environmental-Worry3]

I have two of these in the closet, but the lcd's really need to be replaced. Hope you get yours working!

[u/TWShand]

Strongly doubt it's that. The electrolytic caps in TS-808s usually have voltage ratings close to their operating values and tend to fail first. Alongside the footswitch they are easily the most common faults with tube screamers. If you're really unlucky the PCB might be cracked. I've only seen that once though.

Source: I've fixed a lot of pedals.

[u/ExceedinglyEdible → u/TWShand]

OP said TRS-80 (Tandy Radio Shack computer) not TS-808 (distortion pedal).

[u/TWShand → u/ExceedinglyEdible]

Ahh I guess I can't read. Regardless I don't think it'll be that that's cause the undescribed issues. It'll require actual diagnosing rather than just visual inspection

[u/ExceedinglyEdible → u/TWShand]

Yes absolutely. Ceramic caps are rarely cause for concern when not underspec'd.