Fixing the Grundy NewBrains

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adrm
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Fixing the Grundy NewBrains

Post by adrm » Mon Oct 22, 2018 1:20 pm

Having fixed my second Atari XEGS, plus finishing (mostly) upgrading it with a VBXE board (mostly to get RGB output), I found myself with a few more days to take a crack at the two dead NewBrains.

The first one (the AD model with the vacuum fluorescent display built in) was easily fixed by changing 3 crusty 10uF capacitors.

A bit of advice needed:

1)
The machine consists of 3 separate PCBs, connected via flat cables made up of wires inside stiff paper. This can fuzzily be seen in this picture (borrowed from a now defunct site.)
old_cable.jpg
old_cable.jpg (20.37 KiB) Viewed 824 times
I'd like to replace these, preferably with something that inserts into sockets for easy disassembly.
On eBay I find lots of these
flat_ebay.jpg
flat_ebay.jpg (6.64 KiB) Viewed 824 times
but I can't seem to find any connectors, let alone any that are suitable for this purpose (The PCB holes seem to have the standard 2,5mm spacing where the ribbons are soldered).

Someone's used this for the same purpose, but I can't seem to find these, either:
new_cable.jpg
new_cable.jpg (25.27 KiB) Viewed 824 times
new_cable2.jpg
new_cable2.jpg (32.94 KiB) Viewed 824 times
2)
I believe the Grundy NewBrain requires an expansion module plugged into the bus to give access to floppy / hard drives, and I don't have such a unit. That leaves audio cassette storage (via a weird plug).
I have heard of people using audio files stored on smartphones as substitute cassette players, but dies anyone know of any other solutions developed specifically for old computers?

Thoughts and ideas are welcome :)
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Tore


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adrm
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Re: Fixing the Grundy NewBrains

Post by adrm » Mon Oct 22, 2018 2:00 pm

Diminished wrote:
Mon Oct 22, 2018 1:42 pm
How about these?

https://www.amazon.co.uk/Aukru-20cm-Fem ... emale+wire
I have some similar ones, although not in the correct widths and lengths. I have ordered more cables and Dupont connectors on eBay some days ago, though.

The NewBrain is very cramped when you fold it together.I think they used the very thin (and flexible) cables because of this.
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Tore

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Re: Fixing the Grundy NewBrains

Post by scruss » Mon Oct 22, 2018 3:50 pm

adrm wrote:
Mon Oct 22, 2018 1:20 pm

I'd like to replace these, preferably with something that inserts into sockets for easy disassembly.
On eBay I find lots of these
flat_ebay.jpg
but I can't seem to find any connectors, let alone any that are suitable for this purpose (The PCB holes seem to have the standard 2,5mm spacing where the ribbons are soldered).
Those look a lot like a Flex Cable for Raspberry Pi Camera. The connectors on that are surface-mount and look like 15-conductor at 1 mm pitch.

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adrm
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Re: Fixing the Grundy NewBrains

Post by adrm » Mon Oct 22, 2018 3:59 pm

Yes, they are probably intended for Raspberries.

But surely there are thin flat cables still available. I recall seeing them in equipment in the past.

The cables in my last two pictures must be new, I guess
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Tore

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sirmorris
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Re: Fixing the Grundy NewBrains

Post by sirmorris » Tue Oct 23, 2018 7:34 am

Samtec do a range of pre-made cables. Check out their range and if you find anything suitable let me know and I may be able to get one for you.

Would something like this do?

https://www.samtec.com/products/idms

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adrm
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Re: Fixing the Grundy NewBrains

Post by adrm » Tue Oct 23, 2018 8:33 am

sirmorris wrote:
Tue Oct 23, 2018 7:34 am
Samtec do a range of pre-made cables. Check out their range and if you find anything suitable let me know and I may be able to get one for you.

Would something like this do?

https://www.samtec.com/products/idms
I think this example might work for one of the connections (main board - keyboard), but not for the other (main board - memory board).

I'll post pictures and measurements of the original solution this evening. I think this will make the challenges clearer. :)
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Tore

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adrm
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Re: Fixing the Grundy NewBrains

Post by adrm » Tue Oct 23, 2018 3:46 pm

Here are a number of photos of the Grundy NewBrain AD.
Note that the connection between the Main Board and the RAM Board has a total of 4 ribbon cables, each with 10 leads.
MB to Keyboard is 1 cable with 12 leads.
555A4080.jpg
555A4083.jpg
555A4084.jpg
555A4085.jpg
555A4087.jpg
555A4093.jpg
555A4098.jpg
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Tore

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