The ROMS in the 2220 are 1603976-04 and 160-3975-04, different to the 2230 and a quick comparison between the boards doesn't appear to have much difference apart from the obvious lack of cursor control and missing switches.
I don't think the X is a cal feature, at least I've never seen it and don't see what use it would be. Very strange.
---In TekScopes@..., <edbreya@...> wrote :
I don't recall exactly how the 2220 was differentiated from the 2230 for product positioning, but I do know the guts are mostly the same. I think the 2220 was reduced in performance by limiting the BW to 60 MHz (with parts on the main board) vs 100 for the 2230, and maybe lower sample rate and record length. I think the brain identified the model by jumpers (0 ohm resistor jumpers) on the digital board, although they may instead have different ROMs. If anyone with these models can compare, it would be evident. I also thought the 2220 had on-screen readout, but fewer features within the operating menus.
If the ROMs are the same between models, this could be a case where a 2220 can be mostly converted to a 2230, except for any major items missing.
I saw the picture of the big X - it certainly is big, and appears to be generated by the digital display system, like a calibration signal to align the storage mode to the CRT face. Maybe there's a jumper or DIP switch set to the wrong position, or loose, forcing a cal mode. Another possibility is that it's a fault indicator showing X-out - that there's a major problem such as the brain being confused about what model it should be, so it just sits there. Perhaps there's an intermittent fault in the ID process, or maybe someone hacked it part way and got it all confused. Obviously, the brain must be working in order to present the X on screen.
I'd recommend studying the manuals and circuits and boards and ROMs and jumpers and DIP switches to see if anything looks different from normal. Especially check in the adjustments section, to see what's done for aligning the store/nonstore registration. I'd guess it's a jumper or DIP switch setting, rather than a diagnostic menu item, to make the X, and pots on the vector board to tweak it to the CRT.
Ed
