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Thanks for that. 10R does seem a bit low but that's cheap Chinese ohms!

One thing that bothers me a bit is the very low resistance between 5v and GND, around 10 ohms.

Yes it does and that's what I see. It should be taken low by the Reset handler but that never happens in my case.

I think its the other way round. /RESET is active low so execution should start when it goes high. That was my next step to probe the address lines, but Im pondering what could stop the cpu from starting e.g. a clamped interrupt line. All the jumpers are fitted, I even changed the W1 jumper as...

OK, I've done a detailed examination of the board (both sides) and while I found a few areas where the solder mask was discoloured, when I scraped it away the trace was good. I've also buzzed out all of the major components and found one of my repairs was bad (but only a connection to the SCSI...

Well that's a relief. Thanks for the tip, I'll try the scalpel test although I do try to buzz test on the pins without much pressure. Yes, I've had that too on an Acorn A3020 (battery leakage) Another great tip. Its easy to get distracted though and miss something. I'm trying to put together...

Unfortunately mine isn't socketed so its going to be a pig to get out. 128 pin PGA sockets seem like hen's teeth (or extremely expensive) too.

16MHz 68030 chips seem scarce, anyone know if a higher rated one (e.g. 25MHz) can be used?

Well the Overlay line has continuity but I can't see any activation on it. It goes high on switch on and stays there. Scoping the address and data buses shows no activity at all. I've probed the CPU (not buses) and every pin is high except E1 CLK (shows a ragged sine wave), C1 FC1, E2 AVEC, J12...

Of course you are right, its handling 32bit words so A0 and A1 aren't needed (always 0) I was trying to track that down. It is UK6 pin 6 connecting to UK13 (GLU) pin 49. I'll check for continuity and then put the scope on it.

Hmm, Address and Data buses between CPU and ROM all buzz out OK. The first thing that happens on reset is for the CPU to get the Reset Vector from address $0. I'm struggling to find where this comes from. It can't be in ROM as they don't have address lines A0 and A1. Does it come from the GLUE...

Here are a few of images to give an idea of what I faced. This is what the machine looked like when I got it And this was the battery damage I found. Luckily it looks like the machine was stored on its side, minimising the damage. This is after my repair attempts, the power is starting up OK...

I'm interested in any developments here as I'm in the same boat' I've rebuilt the badly damaged startup circuit on my IIcx and recapped. I can now get it to power on but it doesn't seem to even try booting. See https://68kmla.org/bb/index.php?threads/restoring-my-iicx.48705 for details of my...