Re: Lisa 2 Repair

Some CPU boards do not have the capacitor added-on to the chip at C5. You probably don't need it unless there is evidence it was there and was torn off. It is related to the parity error circuitry, so it would not have the effect of completely preventing the computer from starting up.

There are original Apple changes to Lisa boards that could look like damage has broken a trace. You will need to be very specific to enable us to tell if it is intentional, it probably is.

The orange wire sounds like it may be a repair. If so, it is probably due to corrosion from battery leakage and you will need to check all the circuitry in that area. Is it one of the wires in this photo:

   http://www.pagetable.com/docs/lisa_boards/io_front.jpg

I have not heard of anyone re-capping the entire computer, but sometimes the Power Supply. Have you checked the voltages?

>I've looked at pictures for lisa boards online, and I found one
>difference on my CPU board. The chip right under the video ROM (the
>one with two ceramic caps surrounding it) apparently is supposed to
>have another ceramic cap attached to leads on either side of it, as
>shown in this picture:
>http://www.pagetable.com/docs/lisa_boards/cpu_front.jpg. My lisa
>does not have this capacitor installed. Could this be a problem?

>Also, on my system's IO board (it doesn't have batteries), right
>before the orange wire connects to the board around where the
>batteries used to be, there is a chip in the board that might
>completely have severed the trace leading up to that wire. Is this a
>major problem or can it be overlooked?

>Finally, should I consider re-capping the entire computer?

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