Hi All,
Maybe this is old news to sone, but given the fact that it took me 2 days to find a solution, I thought a concise repost is in order.
If you have a sony CRT monitor that is too bright, too dark, as retrace lines or other imaging faults, do not despair, it probably is still working perfectly, but it simply "forgot" the appropriate internal settings in its EEPROM due to an aging CMOS / flash memory. These settings include G2 voltage, factory defaults, geometry settings etc., much more that what you can adjust with the user controls.
But how to correct these "forgotten" settings? On some monitors, you can restore them through a hidden "service menu" or "factory settings" menu. Not so on the Sony monitors. On these, the EEPROM settings are serviced and modified via an I2C bus connector that you can use to interface the monitor's internal logic directly to a laptop running Sony's DAS monitor calibration software.
But where to get it? And where to get the interface cable? Most posts said this was impossible to find, and instead recommended crudely soldering some parts into the monitor instead of software-adjusting the correct registers.
Short conclusion: All the info, including the Sony DAS software WinDAS, can be found here:
Thousand thanks to whoever gregua is. Thanks Sony's unreliable flash memory and thanks to Gregua, I probably have obtained a perfectly servicable GDM-FW900 23" Flat Wide Screen Trinitron CRT for free!