exxos's Atari, Amiga & retro forum

Well, that was a pleasant surprise. The PLA and MMU just appeared via the postie, which I wasn't expecting since I only got the eBay email saying they were dispatched this morning!!

So the desolder gun is warming up and we'll get this old one swapped out :)

Could be a good day as the PAL <=> NTSC adapter for the OSI should be here later on, and possibly the SD card cassette for the MZ-700 too :)

@rubber_jonnie should be a fun and productive day for you

PhilC wrote: 17 Feb 2024 11:48 @rubber_jonnie should be a fun and productive day for you

Nice quick change thanks to the desoldering gun:


Or as some YouTubers like to call it, 'The Moo Gun'.

Very glad I got a replacement gun for my base unit, it works really well and cleared the holes so well I just needed a tiny bit of heat on one pin to get the old PLA out.

Turns out the PLA isn't at fault though, or the MMU. I've swapped both and whilst I can still get into C64 mode using the boot time keypress, C128 mode is just not happy, with a blank screen most of the time, and neither run the diag carts anymore. Or any carts for that matter.

I swapped the PLA and MMU back to the old ones and it's just the same, and I can't shake the feeling that handling the board made it worse, so could it be a mechanical issue like a dry joint?

I'll come back to it later and probably Electrolube all the sockets that I haven't yet done and give the underside a really close look.

Right now though, I need to walk the dog :)

@rubber_jonnie swap out the single wipe socket of the mmu. I bet it’s that as I’ve seen that behaviour before.

PhilC wrote: 17 Feb 2024 12:39 @rubber_jonnie swap out the single wipe socket of the mmu. I bet it’s that as I’ve seen that behaviour before.

Hmm, I thought it was a double wipe, but I'll check later, thanks.

My whole board was a single wipe, hopefully you’re luckier.

I hope it's a simple fix. I guess that there's a whole load of buzzing out traces in your future.

stephen_usher wrote: 17 Feb 2024 13:29 I hope it's a simple fix. I guess that there's a whole load of buzzing out traces in your future.

Me too, it looked to be a simple fix when I sold it.

Particularly troublesome chips I found on those C128 boards were the 74LS 06, 08. 257.& 244s

I can give you a few tips if needed but without the MMU doing its thing you won’t get much else

PhilC wrote: 17 Feb 2024 13:40

stephen_usher wrote: 17 Feb 2024 13:29 I hope it's a simple fix. I guess that there's a whole load of buzzing out traces in your future.

Me too, it looked to be a simple fix when I sold it.

Particularly troublesome chips I found on those C128 boards were the 74LS 06, 08. 257.& 244s

I can give you a few tips if needed but without the MMU doing its thing you won’t get much else

Honestly, I don't mind as I knew it wasn't 100%, and I enjoy the fault finding side of things.

I'll start by looking at all the sockets and see how they're doing, take it from there.

244s are always iffy. :-)