Recent content by Kai Robinson

Just so you know the SND is not a Programmable device, it's fixed state hardware using logic gates and discrete components. You'll want something like a TL866 programmer for SPLD, ROMs and use them for testing 74 series logic.

Yep, that's them!

Nope - those are the 65C22S's - not the 65C22N's which have an open drain output, designed to replace old NMOS parts like the SE/30 uses. I'm trying to find a W65C22N6TPLG-14 but it looks like mouser are the only stockists of WDC parts and the 'N' variant is only available in DIP not PLCC at...

Well, i mean both harvested from an original board AND from sources like UTSource - i'd still not rule out either VIA even if the chips were clean, they could still be faulty/totally dead. Worth testing with fresh, new ones from mouser/digikey. They're not expensive.

Ah, this might be the issue. @techknight and @This Does Not Compute had an issue with a reloaded board using harvested VIA's - they're just standard, off the shelf, 65C22N chips, get them from either mouser or digikey.

Are the via chips new, or harvested?

If CPU wasn't working you wouldn't be getting a chime, likewise with the GLU - honestly i think it's either RAM MUX/resistor packs, something to do with the PAL logic.

I'd imagine the ROM is fine, given the death chime. When my Iifx went wonky, turned out to be poor oscillator connection and clock signal.

Hi Steve - hope you don't mind me undeleting this - it's a valid question that others might find useful to leave up and around. Also the IIx and IIcx GLUE is the same, iirc, as the SE/30 is a IIcx in a compact chassis with 1-bit video.

As long as you can see the waveform shape and aren't measuring high clock rates, for basic stuff, that should be OK.

Never disregard anything when diagnosing - after all, the original run of boards had transistors fitted at the factory, not diodes.

Have you checked all the 74 series logic thats interfacing with the RAM?

Confirmed - L2 is a BAS40-06 Diode.

Go for it!

Hi - I merely posted the link, i've not used the tools - check the link itself in the initial post, which will send you to GitHub and explain more than this thread.