exxos's Atari, Amiga & retro forum

olivier.jan wrote: 10 Jan 2022 14:21 Pretty common issues are the infamous MT RAM chips and the delay line. Mine had a dead RAm chip which caused it to go in storage in 84 until I found it in a bag and repaired it 2 years ago.

Yeah, I did look at the RAM suspiciously when I opened it up :)

Mine has TMS RAM installed.

@rubber_jonnie worth trying the piggyback ram trick check.

You have to upgrade it to 64k anyway in order to use U1MB and others, so it might be quicker to replace the RAM anyway.

PhilC wrote: 10 Jan 2022 15:16 @rubber_jonnie worth trying the piggyback ram trick check.

If I have some spare, I can. Need to rifle through my parts box, see what I have in there.

olivier.jan wrote: 10 Jan 2022 15:19 You have to upgrade it to 64k anyway in order to use U1MB and others, so it might be quicker to replace the RAM anyway.

True, but I'd rather get it working in original config first to make sure I have a solid platform for when I do upgrade. Also, as it's my first one, I don't want to complicate matters when troubleshooting.

Your point is a very valid one though.

So, the 600XL has every last chip socketed and all single wipe sockets!!

I hate those buggers, I'll have to give them all a dam close inspection, and not to mention the sockets of two 74LS chips that the legs have gone black on. They need to come out for a clean and a spot of contact cleaner, then if it still doesn't boot, I think we'll need to get the scope out.

Very annoying as I have the Mac Classic, Aquarius and 600XL on the bench, so I need to make some space!!

After doing some research, it seems that ROM, RAM & MMU are all the things that go bad, those and the single wipe sockets!!

So I am going to replace the sockets for the GTIA, Antic, SALLY, PIA, Pokey, OS and Basic. I have the sockets, all dual wipe, so i think it's worthwhile doing. I may also do the remaining smaller sockets, but want to get the main ones out of the way first.

I have a spare MMU from both the 800XL and 65XE due to their U1MB upgrades, so that's handy for testing, plus I have spare OS ROMs and a couple of Pokeys too from the same. That'll help at least isolate some of the ICs, but I may not be able to borrow much from the 800XL as a lot is socketed, and a few of the parts have wires soldered to them for the U1MB upgrades.

We'll see how we go.

@olivier.jan I have decided I may do the RAM upgrade to 64 K and have RAM on the way. As you say, I'll need to do it pre U1MB anyway.

Ok, so the 64KB ram is here now, so once I have some time I can get working on this machine again, as I have all the sockets I need to replace the awful single wipe ones it currently has.

I think I need to pull the lid off the 800XL too, see what parts are socketed that I can borrow for testing.

rubber_jonnie wrote: 13 Jan 2022 14:21I think I need to pull the lid off the 800XL too, see what parts are socketed that I can borrow for testing.

In early 800XL (not XLF) all Atari specific chips (excl. ROMs) are in sockets...

tzok wrote: 13 Jan 2022 19:58

rubber_jonnie wrote: 13 Jan 2022 14:21I think I need to pull the lid off the 800XL too, see what parts are socketed that I can borrow for testing.

In early 800XL (not XLF) all Atari specific chips (excl. ROMs) are in sockets...

The 600XL has everything in a socket for sure, my 800XL I think has a mix, as I did have to desolder the MMU in order to fit the U1MB. Trouble is I can't remember much more, so the lid will have to come off to help my crappy memory :lolbig: