Sinclair ZX80 / ZX81 / Z88 Forums

Well thanks to a faulty monitor my ZXPand+AY has bitten the dust after it put 96vac down the audio lead. Looks like the PIC, Gals and ROM at least are dead and possibly the AY chip. So basically every chip on it.

I gather these are no longer available? (I have no way of programming a GAL chip or the PIC)

OK so after burning a new rom and swapping the PIC chip out with the one from my ZX80 ZXPand I have identified the PIC chip as faulty.

Can this just be replaced or does it need to be programmed first?

Thanks

Actually it seems to have updated the chip fine after the swap.

Now to test the AY

Yes, PIC chips are easy to program, you need a PICkit programmer. The clones of the PICkit2 from China are apparently okay. Or you can buy the latest official version from Microchip.

I can’t remember if the ZXpand has holes/pads for a in circuit programming pin header. But it’s not hard to solder a IC socket and pin header to a piece of stripboard. Then wire it up.

A working PIC in a working ZXpand can have its “firmware” updated from the SD card.

Mark

I got in touch with sirmorris when my zxpand died and he was happy to repair it. If you have trouble with yours get in touch with him and see what he says. Worth a shot!