Atari Falcon motheboard issue / damage

[nokturnal]

Hi, I digged out old Falcon motherboard, which I broke somehow years ago (and really don't know how), and I wonder if I could fix it. It was earlier fixed by R.Czuba, and got bus accelerator mod (to expose some signals to ct60).
In general I've connected old falcon psu (voltages are ok), W11 jumper is set, checked two different 4mb ST ram modules. Unfortunately diagnostic cartridge doesn't boot. Screen looks like this (on rgb monitor, it constantly rolls, like there was no horizontal sync):

f030_screen_002.jpeg

f030_screen_001.jpeg

Anyone has seen something similar before? How can I diagnose issue here?

[Badwolf]

Leaving aside the display issue for now, as there are likely bigger fish to fry.

If the diagnostic cart doesn't produce anything on the serial port, then I'd be looking at ROM or shorts/breaks on the data bus.

Assuming basics (voltages, clock signals, reset not stuck low) have been ruled out, my next port of call would be a cheap logic analyser attached to the expansion port to see what's going on after reset.

The diagnostic cart is checked for and run very early in the boot process, so if you're getting nothing there the problem is fairly fundamental.

BW

[nokturnal]

Thank you, there's no output via serial (which is working on other falcon). I will check other things and probably I will have to revisit repairs and modifications done this mb.

[mikro]

If the idea was to connect wires to the CT60 pads, I can't imagine having this motherboard without some sort of cuts, i.e. most likely it can't work in stock.

[mrbombermillzy]

I had a similar situation with my F030.

When I purchased it, there was a blowup 3in1 board in there and an accellerator had already been (literally) ripped out. It sort of booted, but would crash with any sort of trying to run software, other than what was in the auto folder, obviously.

Whatever the booster was in there, it was one that stole the DSP's interrupt line (and it wasn't restored after removal, amongst other things).

The only way I got any sense was to remove the blowup board, reverse the mods for that and then recap the board and PSU and try to restore the board back to the revision work it should have had from stock. It's probably the easier route, rather than having all that modded stuff in there in an unknown state of repair.

@Steve did the board restore and PSU recap for me. That was a great job done. :D

[nokturnal]

@mikro: Yes, I had to revert everything, according to ct60 fitting with solders instructions from official page.