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Re: It's long overdue - Cosmac Elf II build

Posted: 30 Apr 2026 17:00
by rubber_jonnie
HigashiJun wrote: 30 Apr 2026 14:24 Oh no...

:(
I'm a bit gutted...

I will spend some time with it to see if there are shorts I may have missed. Might have to remove IC's to see if there is anything bridged underneath.

Re: It's long overdue - Cosmac Elf II build

Posted: 30 Apr 2026 18:15
by stephen_usher
Could be a "phantom short" caused by flux which has become conductive.

Re: It's long overdue - Cosmac Elf II build

Posted: 30 Apr 2026 19:31
by rubber_jonnie
stephen_usher wrote: 30 Apr 2026 18:15 Could be a "phantom short" caused by flux which has become conductive.
Possibly, I need to have a good look but I did give it a damn good clen.

Re: It's long overdue - Cosmac Elf II build

Posted: 05 May 2026 10:34
by rubber_jonnie
So, I have an option for the CDP1861 replacement :)

I found an earlier incarnation that uses a bigger PCB and through hole components, so I've ordered those via a project on PCBWay so at least the creator will get something back.

In the meantime I do wonder if there is a short somewhere in the PCB from the solder paste I used, so I think I'll use a spare PCB and transfer over the components and either hand solder or hot air solder them on but not using solder paste.

No harm doing so, and what I might do is remove one IC at a time to see if a particular one is causing the machine to hang.

Also, my expansion slots are in the UK so that should be coming soon :)

Re: It's long overdue - Cosmac Elf II build

Posted: 05 May 2026 13:49
by HigashiJun
Cannot wait seeing the final result.

8-)

Re: It's long overdue - Cosmac Elf II build

Posted: 05 May 2026 14:27
by rubber_jonnie
HigashiJun wrote: 05 May 2026 13:49 Cannot wait seeing the final result.

8-)
Me either!

Re: It's long overdue - Cosmac Elf II build

Posted: 06 May 2026 22:11
by rubber_jonnie
Well the connectors arrived today and they look spot on:

IMG20260506220030.jpg

They aren't soldered in yet as I've been in London all day, but they fit perfectly so pleased with the result. I think I'll wait until I have one of the expansion boards before I solder them all in as with 86 pins each, that's a lot of soldering if the expansion cards don't fit!!!

The PCB's for the alternate CDP1861 are nearly done, 93% according to the order so fingers crossed I'll have those relatively quickly as I did cheap out on the postage :)

EDIT: PCBs just shipped.

Re: It's long overdue - Cosmac Elf II build

Posted: 15 May 2026 14:31
by rubber_jonnie
Well the alternate CDP1861 boards arrived today:

IMG20260515141109.jpg

As I'm away next week it'll probably mean I won't be able to build until I get back, and I'll be away 10 days...

I guess we'll all just have to be patient :)

Re: It's long overdue - Cosmac Elf II build

Posted: 15 May 2026 16:12
by rubber_jonnie
Ooops, paerhaps patience isn't my thing...

IMG20260515161013.jpg

Unfortunately whilst I may have the GALs I'm not sure about the rest, so that will have to wait until i get back from hols.

Re: It's long overdue - Cosmac Elf II build

Posted: 15 May 2026 23:52
by HigashiJun
Enjoy your holiday !