exxos's Atari, Amiga & retro forum

PhilC wrote: 07 Jun 2026 09:30

Icky wrote: 07 Jun 2026 09:15 You got one @PhilC and an intact joystick.

Mine also came from Egypt. There are a lot of mods for the Enterprise does this one have any already? It's a lovely machine.

I must confess that it's a 3d printed joystick knob and expansion port cover. I'll resin print some better ones.

I've been assured it works but not tried it yet. I do intend to make a spectrum emulator cart and the 1.5mb ram upgrade for it.

Ah yes they are rare as hens teeth. Mine is missing and haven't gotten round to 3D printing one yet. My Enterprise currently is stock and haven't had the time to look into that mods I want to do.

Exercising my brain today by trying to fix a cheap Apple //e motherboard.

I managed to pick up an //e motherboard and PSU for a good price the other week. So the PSU has had the Rifa's and the low voltage caps replaced.

So now just fired up the motherboard and we get this:
Checked the ram and it's all good, so I've got the scope out and will see what happens. (I'm supposed to be doing the DIY instead).

All voltages and clocks good? How does reset look?

Do you have a keyboard? You might want to try holding CTRL+open Apple+closed Apple and pressing reset and it'll run a built in diagnostic. Well, if it can.

Be aware that there are two custom ICs, the MMU and the IOU. The MMU on mine died, well became marginal and affected by temperature but be aware there are PAL and NTSC versions so if the MMU is bad be careful what you buy. I don't think the IOU is region specific.

One thing though, the sockets are plain awful single wipe types, so at the very least I'd suggest you hit them all with contact cleaner and check the chip legs for corrosion or tarnishing.

thanks @rubber_jonnie the sockets are all a bit crusty, so that's where I'm starting from.

PhilC wrote: 27 Jul 2026 14:38 thanks @rubber_jonnie the sockets are all a bit crusty, so that's where I'm starting from.

I'm lucky enough to have a working board spare :) But the sockets on that are nasty too.

I did replace some on my main IIe when I was having issues with the MMU, but it took a new MMU to fix it.

I 'think' I have the old MMU even though it is marginal, it would at least allow you to boot and prove one way or the other, but I'd need to go find it if you want it.

rubber_jonnie wrote: 27 Jul 2026 14:56

PhilC wrote: 27 Jul 2026 14:38 thanks @rubber_jonnie the sockets are all a bit crusty, so that's where I'm starting from.

I'm lucky enough to have a working board spare :) But the sockets on that are nasty too.

I did replace some on my main IIe when I was having issues with the MMU, but it took a new MMU to fix it.

I 'think' I have the old MMU even though it is marginal, it would at least allow you to boot and prove one way or the other, but I'd need to go find it if you want it.

I'll see what I can find with the Scope. I've got a fully working enhanced //e but not really fancying taking bits off it to test this board. No keyboard either as of yet.

PhilC wrote: 27 Jul 2026 15:06

rubber_jonnie wrote: 27 Jul 2026 14:56

I'm lucky enough to have a working board spare :) But the sockets on that are nasty too.

I did replace some on my main IIe when I was having issues with the MMU, but it took a new MMU to fix it.

I 'think' I have the old MMU even though it is marginal, it would at least allow you to boot and prove one way or the other, but I'd need to go find it if you want it.

I'll see what I can find with the Scope. I've got a fully working enhanced //e but not really fancying taking bits off it to test this board. No keyboard either as of yet.

I wouldn't want to dismantle my working IIe either, it's bot pretty much a full complement of cards so not something I want to pull apart often, if at all.

Saying that I don't have a spare PSU for my spare board, nor a spare keyboard, so I'd need an alternative to start playing with it.

Also, the composite signal is pretty terrible, I'm not a fan hence why I have a V2 Analog VGA board.

Just founding issue with the motherboard, the EF rom was dropping the voltages on the databus. The CPU was also randomly pausing.

So, since these were thew only rooms that I had and that I had a spare 65C02, I've done the enhanced update to the board. Still the same output on the screen but now the database looks fine and the CPU no longer pauses.

One step forward then.

Okay so I'm parking the //e motherboard for now. I've got some good activity on the bus, so I'd next like to try and IOU or MMU replacement.

Absolutely no rush to fix this as it's basically a spare for my original //e and am happy with the results so far as I also now have a spare recapped and working PSU.

See....... I can tidy my bench, I just choose not too.
I changed the rubber sheet on my bench, so I had to do some tidying. The minimum of tidying that is.

I predict in ten mins it'll be back to it's normal messy conditions.