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atari030 · Post by **atari030** » 05 May 2022 00:52

Well after a pretty poor nights sleep and a look at the schematics....

I had a quick buzz over the board this morning and found my multimeter has crapped itself. I guess that's two, karma usually comes in threes.

Looking at the schematics and the fact I have an image of sorts I'm hoping I've just cooked the driver transistors. I'll order another shifter anyway, in my case it pays to have spares.

Post by **exxos** » 05 May 2022 02:00

If you have a scope then just check the RGB outputs on the shifter itself, I think there is 4 bits on the STE shifter for RGB output. With a colour image on the screen you should see most of them switching.

atari030 · Post by **atari030** » 05 May 2022 02:22

Cheers Chris. No scope, although I can probably half inch the one we have at work. Can't even find my logic prob atm either, I don't know how many times I have put that somewhere safe....

What I don't get is the lead fell over the ferrite bead from the bottom of the cap. Looking at the schematics that should have been common 5v anyway so I'm not sure how it would have killed anything? I'll swap out the trannies and see how I go for now. Its an easy $3 test.

This is the problem with staying up late to do Atari related things. Luckily I only have a couple more projects after this one.

Post by **exxos** » 05 May 2022 06:01

Does the inductor measure shorted still ?

atari030 · Post by **atari030** » 05 May 2022 06:20

I didn't get more than five minutes before work to have a gander. I've bought a new Multimeter so will check when I get home.

atari030 · Post by **atari030** » 05 May 2022 06:40

Forgive my ignorance, its been a while since I've needed to look at inductors. L501 is a ferrite bead, shouldn't that measure as short?

atari030 · Post by **atari030** » 05 May 2022 12:02

Ok, now I understand what you mean. For some reason the spark was the 5v trace between the inductor and cap. The trace had burned out. Whew.

Post by **exxos** » 05 May 2022 12:09

atari030 wrote: 05 May 2022 12:02 Ok, now I understand what you mean. For some reason the spark was the 5v trace between the inductor and cap. The trace had burned out. Whew.

Ah sorry forgot to reply earlier. The inductors should measure as a short. I was thinking because of the spark it may have burnt it out. Seems you are already gone on to the next step of it burning out a track anyway :)

atari030 · Post by **atari030** » 05 May 2022 12:46

I think I will leave the ghost as a reminder. Its odd it blew the trace as the path was the same as the short.

With all the board manipulation it has gone back to odd bombs. Probably a good thing as it clearly isn't over yet.

atari030 · Post by **atari030** » 09 May 2022 12:18

Going over the schematics its looking more and more like a DMA issue. is Best the only likely source of the square package?

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