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And I still don't see where EAROM 0x004C is used. It would still be nice to know if this value even matters. Now that I have the code disassembled maybe I'll poke at it a little more.
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Ok, I think I've got this piece figured out too.
EAROM location 0x4C, as mentioned before, gets read at boot time.
More digging with the code and the logic analyzer shows that once it gets read, it's stored in RAM as a word at locations 0x010F and 0x0110 (MSB then LSB).
RAM 0x010F/0x0110 is then accessed whenever the delta-V button is pushed and the horizontal cursors appear, no matter what traces are currently on the screen.
This leads me to the conclusion that EAROM 0x4C is the calibration constant that is derived in steps "a" and "zz" in the "CAL 02 VERTICAL" adjustment section.
So, stephunk, I would expect the only thing this bad value is affecting is the delta-V cursors. Unfortunately, it's only set at the very end of the vertical cal procedure, so I don't think it's possible to do a cal just on that. You'd have to go through at least the vertical cal, and the manual doesn't generally recommend doing partial calibrations anyway unless you're sure the previous calibration sections are ok.
The only other thing I think you could do is build a circuit to write values to the EAROM, and then try different values that 1) makes the the delta-V cursors work properly, and 2) satisfy the checksum algorithm
But that's a lot of work. It's easier to buy or find someone with the needed signal generator to do the cal. Maybe search around for people who have done ad-hoc solutions to calibrate these 24xx scopes.
I think I'm done. I seem to be the only one left in this conversation.
EDIT: Added pic of 2465 being probed. Fun!