Re: lisa 2 startup problems

hi james,

thank you for the answer, we are talking about a lisa 2/5 with 2/5 motherboard and card cage.

I would still like to use the original 2/5 io board but now it dies on me again. i just described the new symptoms some minutes ago.

joi, 1 noiembrie 2012, 21:35:39 UTC+2, Alex a scris:
>
> Hello all,
>
> I recently acquired a Lisa 2 (Macintosh XL) with the 2/5 motherboard, old
> IO board with the coprocessor socket and battery pack and 800k Floppy ROM,
> CPU board with ROM's dated 1985 and 2 x 512k RAM cards. The problem is, it
> won't start. The motherboard was badly corroded but I cleaned the corrosion
> with vinegar and alcohol and it looks decent now, I could not find any
> broken circuits.
>
> What I already tested:
> - Power supply is OK (+5V standby voltage present, replaced all
> electrolytic capacitors)
> - on the COP421 chip I can measure the power button signal when I press
> the power button but the state of pin 24 remains the same
> - i can "force" start the power supply by applying 5V on the ON pin of the
> COP421 (pin 24).
> - the power supply starts with no problems, correct voltages present on
> the I/O board
>
> - I can only get a grey picture with some horizontal lines but no sound
> and no video
> - unfortunately I have no other boards to switch out for testing.
>
> - does anybody have a clue where to start digging for reparing this lisa?
>

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