[swenhold4]

Good evening all,
I'm stuck again on the next phase of my initialization journey. I thought things were really going well and I got myself to the point where I was ready to load tools in. Problems started when it came to actually storing the data I would enter.
The control couldn't remember what tool it was measuring, couldn't hold offsets to locate the measurements, but would remember it's reference point.
I dug a little and found a memory test page in the Check menus, and sure enough I received ram parity errors.
Basically, you initialize the test and there's a report that spits out an IC#, a memory address, the bit written, and the bit read. It was all fairly repeatable, and the 2 consistencies were the IC#'s, 1M & 1N.
After much back and forth I decided to assume the IC# was hopefully actually referring to the IC chip on the LX64C board, which were just three stage line buffer chips but what do I know. I was hoping to test the chips, but they ended up falling apart on the way out of the board. Probably weren't helping to say the least, so new ones were installed.
Now I'm still getting the same series of errors, but now all the read bits are much more consistent. They're all coming back C0, what that means I have no idea.

Short of reverse engineering the entire circuitry around those chips, and maybe even replacing a couple more in the area, I am kind of at the end of my rope. Mitsubishi wants a "Flat rate repair" fee of over $2k, so that wasn't going to happen. I'm not even sure they could fix it because their troubleshooting info was nil.

Last I checked, the voltage regulator chip for the board was putting out 5.1V just like it should, so the variable resistor solution that I did happen to find on MEAU's website doesn't seem to be applicable here. I'm thinking there's something bleeding signal off of the circuit somewhere, but I'm at a loss until I can get some more information.

If there's anybody out there who still knows how to work on these sorts of memory boards I'd really appreciate an assist, at least in some idea on what to test for. There's no checksum or anything like in a regular PC so I'm really hoping that I'm understanding the RAM check page correctly. If someone can point me in the right direction here I'd greatly appreciate it.
Thanks

[swenhold4]

Good afternoon everybody, I wanted to give an update on how this turned out.
In short, I believe the 1M & 1N designations in the RAM parity check refer to the placement on the board relative to the cluster of RAM chips.
After laying out all of the pathways and circuitry schematic I could determine relevant to those chips, I could not find anything that could conceivably be causing errors to the order of a bad diode/capacitor/transistor/etc.
I ended up going with a gut feeling and replaced the two RAM chips that would coincide with the first row of chips, aligning with board columns M & N. Sure enough, now there's no more ram parity errors. It's very early on yet as I have not been able to get back, but it also appears that my screen layouts are much better and after rerunning the parameter punched tape I have no more errors, short of A44 which is just resetting the hour meter on either the coolant or gear oil filter, not sure yet.
Anyways, just wanted to share that bit of knowledge with the world.
Thanks

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