exxos's Atari, Amiga & retro forum

G'day all, I was wondering if anyone knows what the difference (if any) between C301705-001, C300584 and C301224 SCU chips is? I'm working on a MegaSTE, I have a few spares but just want to confirm what can and can't be subbed. Mine has C301705-001 but I have a C301224 in the spares box. It looks to be the same thing?

The machine I am working on has a socketed blitter, I'm trying to get my head around the Shifter/Blitter permutations. My other MegaSTE has no blitter but seems to be an earlier model (it came with TOS 2.05 originally). There doesn't seem to be any rhyme or reason to the combos.

Initially this one had a solid white screen, I've reflowed a few crappy joints and I did find one O/C line at the ROMs which I corrected. Now its black screen but seems to switch white after a while, occasionally.... I plan to get a diag cart once post can be trusted, Melbourne is in lockdown again and I cant easily get to electronics stores, mail is pretty much at a stand still so online is pretty much pointless atm. So I figure its time to get stuck into the projects in the Atari pile but I have to make do with what I have.

Have a look here: http://www.best-electronics-ca.com/custom-i.htm

It's a list of Atari custom ICs and may point you in the right direction. I think all the chips you mentioned are GLUE.

BTW a diag cart and a null modem cable make an excellent investment!

That's where I got my info. I figured that was the case. Cheers. Once that post starts flowing, I'll grab one. I'm confident I can get this one up and running but with the number of chips on these things it makes a Falcon look like a picnic.

atari030 wrote: 20 Jul 2020 14:48 That's where I got my info. I figured that was the case. Cheers. Once that post starts flowing, I'll grab one. I'm confident I can get this one up and running but with the number of chips on these things it makes a Falcon look like a picnic.

I think it's just a case of different part numbers equating to different suppliers, the only differences being where chips were combined into one and made surface mount.

This is a must on the sockets

https://www.exxosforum.co.uk/forum/viewt ... =17&t=1484

And look for corrosion around the vme bus and rom bad grounds

Tom

That's perfect Frank, thanks. I usually resort to a pin behind the socket, they are a PITA when they go wrong. No fun to replace and there is definite corrosion on the board.
I plan on getting a de-solder pump/gun, I need to remove RAM from a MegaST as well, it needs doing. Any recommendations on what to get and what not to get? I am looking at one of these, I can buy locally.

https://www.amazon.com.au/Desoldering-R ... B07KRSVCMB

I have one of these: https://www.amazon.co.uk/DESOLDERING-ST ... 157&sr=8-3

It's the best tool I ever bought, though I quickly looked via the link you shared and they don't seem to have them. Closest I could see va your link was this: https://www.amazon.com.au/DOSS-Solderin ... ent&sr=1-3 The unit I have is effectively half one of these :)

The Duratool is sold as other brands so you might find it that way. I can't recommend it enough.

Cheers RJ, I'll have a look for one. I used an STE to check my pile of ROM's and decided to install jumpers. The ole solder sucker suffered trying to clear some of the holes. Its time to move up.

atari030 wrote: 21 Jul 2020 09:04 Cheers RJ, I'll have a look for one. I used an STE to check my pile of ROM's and decided to install jumpers. The ole solder sucker suffered trying to clear some of the holes. Its time to move up.

Yep, I originally went for a desolder iron with integrated sucker, but it was just as bad to use as a normal sucker, and simply didn't get hot enough for anything with a large copper plane attached to it.

A proper temperature controlled, trigger operated gun is the way to go, you won't regret it.