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Re: Another Egyptian Enterprise 64
Posted: 24 Sep 2026 11:32
by PhilC
@rubber_jonnie cool that you've got it all running now, thanks to a duff reading on A2.
Re: Another Egyptian Enterprise 64
Posted: 24 Sep 2026 11:36
by rubber_jonnie
PhilC wrote: 24 Sep 2026 11:32
@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!!!
Re: Another Egyptian Enterprise 64
Posted: 24 Sep 2026 11:38
by PhilC
rubber_jonnie wrote: 24 Sep 2026 11:36
PhilC wrote: 24 Sep 2026 11:32
@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.
Re: Another Egyptian Enterprise 64
Posted: 24 Sep 2026 11:57
by rubber_jonnie
PhilC wrote: 24 Sep 2026 11:38
rubber_jonnie wrote: 24 Sep 2026 11:36
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.
Re: Another Egyptian Enterprise 64
Posted: 24 Sep 2026 23:30
by rubber_jonnie
OK, gratuitous shot of the final install of the RAM board.
- PXL_20260924_215540289.jpg (328.18 KiB) Viewed 53 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.
Re: Another Egyptian Enterprise 64
Posted: 25 Sep 2026 10:03
by 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 44 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.
Re: Another Egyptian Enterprise 64
Posted: 25 Sep 2026 10:12
by 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 42 times
Re: Another Egyptian Enterprise 64
Posted: 25 Sep 2026 10:21
by rubber_jonnie
stephen_usher wrote: 25 Sep 2026 10:12
Yeah, looks like the static RAM isn't very static. Definitely not Scotch as it fades away.
images.jpg
Hahaha, I remember that advert :)
Re: Another Egyptian Enterprise 64
Posted: 25 Sep 2026 10:37
by PhilC
That's annoying but then I guess I did get it from AliExpress. Typical that the one I sent you didn't work
Re: Another Egyptian Enterprise 64
Posted: 25 Sep 2026 11:14
by rubber_jonnie
PhilC wrote: 25 Sep 2026 10:37
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...