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A5000 issue 1 PCB

Posted: Sat May 26, 2018 9:35 pm
by DutchAcorn
I recently collected a batch of acorn computers thinking I'd have fun and a good deal, but the state of the computers is actually quite horrible. As I am usually persistent in my repair attempts, this means I'll have a bit more fun than anticipated... :roll:

There is some interesting stuff though. One is an issue 1 A5000 PCB. I thought all A5000s were issue 1 (as marked on the sticker), but on the back side of the PCB they are actually marked as issue 2.

The issue 1 has a different layout, and more socketed chips:
Image
Image

It also has descriptions of the interfaces instead of icons:
Image


It does not work (at all, it seems). Apart from the usual mess around the CMOS area there is corrosion all over the board.

PS: sorry about the off-site image links, I have trouble uploading images to Stardot.

Re: A5000 issue 1 PCB

Posted: Sun May 27, 2018 7:17 am
by flaxcottage
Interesting.

I had a board identical to that.
IMAG0686.jpg
It too was not working, though it had been advertised as working. Before sale the previous owner had 'kindly' cleaned it, wiping away a considerable portion of the CMOS area, tracks, chips, the lot. :(

I have retained a lot of the labelled chips if you need any.

Re: A5000 issue 1 PCB

Posted: Sun May 27, 2018 11:05 am
by lcww1
The extra socketed chips on earlier A5000s are described in this document on overclocking the A5000 - http://qubeserver.com/Qube/projects/A50 ... cking.html - as a set of PALs providing synchronisation logic between the RAM and the IO - in later A5000s this logic was moved into the IOEB chip.

You can see the differences between earlier and later A5000s on Chris’ Acorns here - http://chrisacorns.computinghistory.org ... A5000.html

Re: A5000 issue 1 PCB

Posted: Sun May 27, 2018 6:04 pm
by DutchAcorn
Thanks for the comments, guys! Interesting reads.

@John: thanks for offering help with the chips. Fault finding will take a while but I think the socketed chips are ok (although some have rusty legs).