I'd go through the two motherboards, pull every socketed chip and clean the pins with an artist's eraser, wipe with alcohol and reinstall before I started troubleshooting. Some of the old Texas Instruments chips are notorious for oxidation problems on the pins.

--- In oberheim@yahoogroups.com , "Paulo Palmieri" <paulopalmieri@...> wrote:
>
> I don ´t have the eprom but have an OB-Xa with the same problem.
> In my case the buttons are working but the leds are flickering too and after 20 minutes they light off...
> I suppose that this could be an Eprom problem
>
> Paulo
>
>
>
> ----- Original Message -----
> From: doug1052365
> To: oberheim@yahoogroups.com
> Sent: Tuesday, November 27, 2012 5:43 PM
> Subject: [oberheim] OB-Xa Diagnostic EPROM needed
>
>
>
> I'm trying to repair this OB-Xa w/JL Cooper MIDI.
> Has no sound, all LEDs are flickering, buttons don't change anything.
> The power supply is OK. It seems the CPU is not booting up.
> Does anyone have an image of the Diagnostic EPROM
>
> Thanks
>
> Doug
>