I started on my new ZX-81 replacement board (kit) ZX81+38

Discussions about Sinclair ZX80 and ZX81 Hardware
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mahjongg
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Re: I started on my new ZX-81 replacement board (kit) ZX81+38

Post by mahjongg » Thu Jan 30, 2020 2:46 pm

The layout is coming along nicely, here is a preview, the white lines (ratsnest) are the connections I have yet to make:
Image

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mahjongg
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Re: I started on my new ZX-81 replacement board (kit) ZX81+38

Post by mahjongg » Wed Feb 19, 2020 12:29 pm

I have made 100% all connections. The expansion port is not fully wired, but enough for I / O devices such as the printer, and programmable sound generators and the like. I'm going to add ground planes on both sides.

Image

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1024MAK
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Re: I started on my new ZX-81 replacement board (kit) ZX81+38

Post by 1024MAK » Wed Feb 19, 2020 3:09 pm

Looking a lot better 8-)

Mark

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mahjongg
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Re: I started on my new ZX-81 replacement board (kit) ZX81+38

Post by mahjongg » Wed Feb 26, 2020 11:56 am

Almost finished, only nBUSACK and nWAIT have not yet been routed to the expansion port. The layout is now quite "busy". :lol:
Next week I will attempt to do the two missing connections.

Image

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mahjongg
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Re: I started on my new ZX-81 replacement board (kit) ZX81+38

Post by mahjongg » Wed Mar 04, 2020 11:36 am

Finished the last two remaining signals, and applied copper fills. Next is to tweak solder mask and silk screen:
Image

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mahjongg
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Re: I started on my new ZX-81 replacement board (kit) ZX81+38

Post by mahjongg » Wed Mar 11, 2020 11:54 am

And this is how the PCB will look like:
Image

Next up, ordering the PCB's (ZX81+38 and keyboard PCB) and testing it.

8008guy
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Re: I started on my new ZX-81 replacement board (kit) ZX81+38

Post by 8008guy » Thu Mar 12, 2020 4:12 am

What does the keyboard pcb look like?

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mahjongg
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Re: I started on my new ZX-81 replacement board (kit) ZX81+38

Post by mahjongg » Thu Mar 12, 2020 1:51 pm

It will look like this:
Image

just with some superfluous stuff removed (reset button and LED's). I also designed a keyboard overlay.

Here you can see a prototype, together with my older ZX-81 clone, built from SMT components.

Image

8008guy
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Re: I started on my new ZX-81 replacement board (kit) ZX81+38

Post by 8008guy » Fri Mar 13, 2020 4:19 am

Cool!

nollkolltroll
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Re: I started on my new ZX-81 replacement board (kit) ZX81+38

Post by nollkolltroll » Sat Mar 14, 2020 9:59 am

Looking very good :D
/Adam

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