Sinclair ZX80 / ZX81 / Z88 Forums

Be careful with what you use to get rid of the pen marks, I occidentally dropped a blob of acetone on my space key and it dissolved the legend in a flash!

never mind dissolve the legend....it'll dissolve the keycap eventually

That reminds me of working in the printing industry in the 80s... Acetone was used to clean the ink from the offset printers and after a long day one of the guys asked if I wouldn't mind quickly cleaning the artwork dept where I worked and I accidentally used a rag with acetone whilst cleaning an expensive laser printer wondering why it was totally sticky before suddenly realising that it was melting

I started carefully cleaning the keys tonight simply with water and bathroom cleaning products, happily it does just seem to be a regular felt pen used to write on the keys so they are all cleaning off easily.

I was looking at the photos of the expansion port extension that Fuller supplied with the 90 degree version. I'd really love to have one and convert my case to have that internal layout. The case has the holes marked for both orientations and so the version of the case supplied was cut out appropriately. I wonder if this was left for the end user to do as my case is quite crudely drilled and cut out? I guess I could think about recreating the expansion port extension if I could get accurate measurments. The photo in the other thread has an expansion of some sort insterted inside the case so I can't see the extension fully but I assume that there's a regular expansion port in a vertical position there which then passes through to the free port showing through the back of the case? Does anyone have photos of the extension without anything plugged into it?

thanks

That "extension" board sounds similar to the one you get in some dk'tronics cases.
If it is, all it is, is the PCB tracks wired to extend from an edge-connector socket to a "male" edge-connector on the edge of the PCB, plus, part way along, a PCB with another "male" edge-connector PCB. I forget now, but I think the main "extension" board has pins that the small PCB is soldered to.
The idea being that the Sinclair (or third party) 16k RAM pack can be inserted here, so that it is in the case
I think the dk'tronics version is however smaller (the main "extension" board).

Mark

Hi Mark, that certainly sounds like the same design. It shouldn't be too difficult to reproduce at home aside from the two edge connectors. Perhaps the easiest way would be to have a one off PCB prototype professionally made.

I've cut out the part of the photo with the Fuller extension showing, I suppose the board that's plugged inside in the photo is most likely a 16K expansion.

Here is a picture of a dk'tronics keyboard, case and expansion adapter:

(photo from this web site: https://k1.spdns.de/Vintage/Sinclair/80 ... 0Keyboard/)

Mark

Thanks Mark, that's helpful to see for reference. I'm not sure how to tackle the vertical internal edge connector, if that could be made as a separate part to attach to the main extension board manually I could then get a simple PCB manufactured. I'll start working on the layout in illustrator tonight to reproduce the Fuller extension. Does anyone possibly have the measurements?

The case and keyboard cleaned up well I just need the expansion port extension now. I'm not sure whether to remove the sticker or glue it back down where it's lifted.


Here's a couple of photos of the back/side of the case where you can see that the ports are there to be cut out for either orientation of the board. If I can successfully make the extension I'll hot glue some black plastic inside the case over the other holes so that It could be reverted back.

I use thin double sided tape carefully cut to size for fixing partly loose labels.

Mark