Diagnosing Mac LCIII over serial bus

[Burgertrench]

I have an LCIII which as running perfectly for months but crashed while trying to load ClassiCube 68k and has not booted since. A full recap had been done, C22 polarity fixed and it was overclocked to 33mhz. The error message when it crashed was a bomb with type 10 error code. It now plays the chimes of death straight after startup, with no video output. I've reduced it to the raw board with nothing other than power and speaker attached. Power supply is showing perfect voltages.
I'm now trying to diagnose over the serial port following Steve from Mac84's instructions. The error code it's returning after startup is 2C5156D60003. I can't work out what this means, but think the 3 at the end means it's related to RAM.
I am able to run the ROM check and it's returning a string of zeros, which means the ROM is good. Any time I try to run the address line test it immediately gives the chimes of death again. The error code then changes to 2C5156D60203. I would like to test specific ranges of the built in RAM; I'm not understanding how to set the start and end values in HEX. I'd like to figure out if it's one chip in particular, or if it's something upstream of the memory chips. Is anyone experienced with this and can guide me on it?

 

[letiss]

I've just been trying to diagnose my LCII boot issues over serial ( i get a good chime and grey screen but no progress after that). I've been using Adrian's speadsheet from Adrian's Digital Basement: https://docs.google.com/spreadsheets/...

I've had mixed results with critical tests.

 

[Burgertrench]

I've just been trying to diagnose my LCII boot issues over serial ( i get a good chime and grey screen but no progress after that). I've been using Adrian's speadsheet from Adrian's Digital Basement: https://docs.google.com/spreadsheets/...

I've had mixed results with critical tests.

I've been doing the same. I was receiving errors after doing memory tests, which I wasn't sure were due to bad memory or if the commands I'd issued were wrong. I've now had some luck, by way of downloading the developer notes for this computer. The document gives addresses for the on board RAM and RAM expansion at various sizes. Using this information, I was able to test a RAM stick and confirm it was working, which confirms I am issuing the commands correctly, and by extension confirming the on board RAM is bad.

I really hope someone is able to analyse the Techstep ROMs and replicate the functionality in software, so we can run checks using another computer and don't need to deal with HEX code.