exxos's Atari, Amiga & retro forum

stephen_usher wrote: 24 Jan 2022 08:11 Poor Sally.

:lol:

:2hot:

Bit of me time today with the 600XL. I've managed to open up my 800XL and do some chip swaps. plus I have dug out all my 74LS stock items and swapped what I can for new working items. As yet no joy.

Here's what's been tested so far and is good:

• Pokey (I have 2 working spares)
• Sally (I got a working replacement today)
• GTIA (Just tested OK in my 800XL with Super Salt)
• Antic (Just tested OK in my 800XL with Super Salt)
• O/S ROM (Tested with a known good one from my 800XL)
• MMU (Tested with a known good one from my 800XL)

Unfortunately, the PIA is soldered in on both my 800XL & 65XE, so that's no good. It's a 6520 PIA, so available at least, though looking at the service manual I'm not convinced that it is in a position to break the machine in the way it does, neither the block diagram nor the schematic seem to show that it plays a major part other than I/O for things like the joysticks etc, and removing it makes no change either.

Would have also been nice to test the delay line IC, but that is again soldered in on the 800XL and I don't want to take the risk of breaking anything by removing it.

So I think I'll order up the logic ICs I don't already have as they'll be cheap as chips (!!!!!!), plus a delay line IC as they are also a potential cause of issues and are also quite inexpensive.

It won't hurt to have more 74LS stuff to hand, so that's all good, and in the meantime I can slowly replace the single wipe sockets for the main ICs with something better.

You're like pacman on E's lately @rubber_jonnie, I don't know what you're smoking, but I want some! :lol: :cheers:

exxos wrote: 29 Jan 2022 16:06 Your like pacman on E's lately @rubber_jonnie , I don't know what your smoking, but I want some! :lol: :cheers:

Lol, I have wanted a 600XL for ages and intend to get it up to super spec, just need to make it work first!!

I do seem to have got a lot done of late, it's been a bit of a blur, just hoping my lucky streak doesn't run out!!

Time for a look at Bretts machine again!

I seem to be at my best when I'm busy!

Mmmm, chips....

Fish!

Dandelion & Burdoch! As long as we're doing word association.

In that case, cream soda!

Well, some more of my 74LS spares for the 600XL arrived today, plus some other non LS ICs, and the problem still remains.

So, that means that the final suspects are the delay line IC, the 74LS375 (A latch), the basic ROM or PIA. FlassJazzCat (He of A8 fame, upgrades, code etc) does say it's often the delay line that's the cause of spontaneous 600XL death, so fingers crossed.

Every other IC has been checked with new, and I still get the same reddish brown screen.

I can't test the Basic ROM as it isn't socketed in my other machines, but even if that was dead I'd expect more activity. Literally everything else checks out.

I'm still planning to replace the sockets in the 600XL as well once I've finished up with Brett's STE, which only has a small mod left to do, so hopefully next week.

My money is on the delay line, but it's coming from Poland so may take a bit longer to arrive. Fingers crossed I'll have ruled out the 74LS375 by the time it arrives.

It is annoying as I have checked all the LS chips with my TL866, but the trouble is I'm not so sure I trust the tests 100% as one IC failed, but so did the new ones in the same way.

Fingers crossed it'll be running soon, and if not I'll have to get the big guns out.

Which IC type failed the tests? I've a bunch of 74 logic at home and 2 different ways to test them so I could see if it's a generic issue with the profiles that the TL866 includes - are you using the latest xgpro release?