Re: Sleeping Lisa

From: <jlewczyk_at_email.domain.hidden>
Date: Mon, 6 Nov 2000 21:32:37 GMT

The power supply has a soft-on feature. It supplies a standby voltage to the IO board, which powers a COPS microcontroller chip. This chip recognizes the shorting of the power switch and asserts a "power up" signal to the power supply, which then brings up all the voltages the Lisa requires to run.

For a Lisa 1 or Lisa 2 (not a Mac/XL, whose IO board is different so I can't speak for it)...

You can test the power supply somewhat as follows... To simulate the shorting of the power switch, short IO board pin-119 to ground (IO Pin-113). If this works, the COPS is OK and the connection between the power switch and the IO board is bad.

The signal to the power supply to turn it on is asserted with +5V at pin X (a grey wire that goes to from the supply to the front interlock switch). The +5V standby voltage from the power supply is on the supply's pin 20, which is the white w/yellow wire.

On the IO board, the power supply "turn on" signal is produced by U7F pin 12 (a 74x07) and is also accessable on C33 + (47mf), near the right edge of the io board as viewed from the back near the middle. It comes off the IO board at pin 120, which you can't get at because its on the solder side of the IO board.

Hope this helps. Let me know if you need more info.

If you've had leakage of the batteries (like mine did), then some traces on the motherboard may have been damaged. On mine, it caused open connections between the sockets and the motherboard traces at the points where the socket pins were inserted into the motherboard. I repaired each by soldering wires under the motherboard between locations I found open.

----------original message -----------------------------------------------
My Lisa died a few years back and I recently attempted to revive her. I thought I had a bad power supply but just acquired a new one but I still get no power. I thought I read somewhere if your Lisa is not getting power then it is either the power supply or I/O board. Can anyone confirm this. I did remove the leaking batteries on my I/O board and some minor corrosion was present but I checked all the circuit pathways with a meter and all are ok. I also checked the micro switch in front and it seems ok. I don't know how to test the power button, could this be my problem. Any advice on what to check/try next would be appreciated.



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