Hi,
If you're getting any flashes of the l.e.d., then the software Rom's are alright - the first flash signifies 'Software Checksum O.K.'. The second indicates 'Nmos (scratchpad) Ram O.K.', so it looks like the third section of the Mpu test (Cmos Ram) is failing, i.e. the '5101' Cmos Ram, U8, is faulty. It's a static-sensitive component, and easily damaged. Unfortuanately, it's also now obsolete, and difficult to source. If you remove it from the socket, park it in a piece of black 'static protection' foam. The socket could also be the problem, especially so if the board has been affected by battery leakage.
Unlike Bally and Williams, Stern made the sound pcb an addition to the main Mpu board, without its own processor or software. I'd get the Mpu sorted first, if possible, before trying the sound board, but make sure that the connecting leads are connected right, i.e. pin 1 of Mpu connector to pin 1 of sound board connector, and so on.
With the U6 Rom chip, the important part is the '25A Rom P?' number. Again unlike the other makers, Stern didn't always use a 'utility' Rom as U6, which would be common to all their machines of that age. So you may need the U6 chip specifically from a Magic.
