Another Egyptian Enterprise 64

[PhilC]

@rubber_jonnie cool that you've got it all running now, thanks to a duff reading on A2.

[rubber_jonnie]

@rubber_jonnie cool that you've got it all running now, thanks to a duff reading on A2.

I'm a bit annoyed I didn't pick it up sooner, but I do have a habit of going back across old ground and I think it's a good job I do.

Thank god for the oscilloscope!!!

[PhilC]

@rubber_jonnie cool that you've got it all running now, thanks to a duff reading on A2.

I'm a bit annoyed I didn't pick it up sooner, but I do have a habit of going back across old ground and I think it's a good job I do.

Thank god for the oscilloscope!!!

I had similar with a pull-up on a Mega ST board once, took me half a dozen times to spot it, so know what it feels like.

[rubber_jonnie]

I'm a bit annoyed I didn't pick it up sooner, but I do have a habit of going back across old ground and I think it's a good job I do.

Thank god for the oscilloscope!!!

I had similar with a pull-up on a Mega ST board once, took me half a dozen times to spot it, so know what it feels like.

Yeah, I had a similar issue with a Mega as well, one of the resistor packs was cracked. Interestingly since I reflowed the A2 connection on Dave, it no longer needs the pull up.

If I just boot up the RAM passes, however if I do the advance test it fails. I think it's likely OK though, but I may order another RAM IC for peace of mind.

[rubber_jonnie]

OK, gratuitous shot of the final install of the RAM board.

PXL_20260924_215540289.jpg (328.18 KiB) Viewed 34 times

I ultimately made a plug for the smaller expansion header and soldered the leads directly to the mainboard with a hint of hot glue for strain relief.

All working fine, so I need to get the machine reassembled now and properly test.

[rubber_jonnie]

OK, so I think the RAM IC is bad.

I left it running a simple for next loop printing to screen earlier and it crashed. It was a pretty interesting crash, and I should have taken a pic.

I did it again and it crashed with a black screen, not nearly as interesting...

So I ran the full memory check (It passes the simple one) and get this:

PXL_20260925_090003132.MP.jpg (375.66 KiB) Viewed 25 times

So I've ordered a replacement IC as my own smaller capacity spares don't work in this boards. We'll see how it goes when that arrives.

[stephen_usher]

Yeah, looks like the static RAM isn't very static. Definitely not Scotch as it fades away.

images.jpg (29.23 KiB) Viewed 23 times

[rubber_jonnie]

Yeah, looks like the static RAM isn't very static. Definitely not Scotch as it fades away.


images.jpg

Hahaha, I remember that advert

[PhilC]

That's annoying but then I guess I did get it from AliExpress. Typical that the one I sent you didn't work

[rubber_jonnie]

That's annoying but then I guess I did get it from AliExpress. Typical that the one I sent you didn't work

It's really not a problem, I'm grateful for the PCB, I didn't expect parts with it, so all good.

Ali Express can be good or bad, take your pick...