Ext PSU requirements for old C70243 Rev H 520STM

[microman]

I have an old 520STM (external PSU variety) with a C70243 REV.H motherboard. What are the PSU requirements for it?

As far as I can ascertain it needs +5V ~ 1.5A for main logic, and +12V at a few mA for PAL video encoder and switching between Mono & Colour.

The rest of the +12V is for the RS232 serial drivers together with the -12V.

If I only feed it +5V and +12v will it work other than the serial port or is there anything else that needs -12V?

Thanks

Peter

[Steve]

Literally the exact same question yesterday :)

https://www.exxosforum.co.uk/forum/viewt ... f=9&t=5110