How do old pvms retain settings when powered off?

[jeffez]

Hi,
I have an older sony 2044QM pvm which seems to need it's brightness/contrast and other settings adjusted every time turn it on. Is there a battery save that might need replacing or something else so that it doesn't need setting up every i power it on? There is even a 'memory reset' button so it must be storing the settings somewhere.
The brightness is completly down to the point I thought it wasn't working and in composite mode the image is black and white until I turn the chroma up. Volume isnt retained etc.

[tongshadow]

It's stored inside the EEPROM chip, usually. Or maybe inside the CPU chip.