Re: Apple Lisa 2/5 I/O Board COPS Error

Sounds like the troubleshooting I just had to do. I'd suggest checking pin 14 of the COP. That pin is ~3v when the system is off, 0.5v when the system is on, and 5v when the power state is changing (powering on or off). This pin is supplied power by 1K resistor R46 form the 5v standby rail, and is pulled low by pin 39 on the keyboard 6552 pin 39. If the 6552 had failed it could be holding that pin low, making the COP think the system is already powered up.

On Thu, Nov 30, 2017 at 7:35 PM, <austjeremy_at_email.domain.hidden> wrote:

> My Apple Lisa 2/5 I/O board gives me a COPS chip error. I tested the chip
> in another I/O board it works just fine. I switched out the socket. I
> checked for continuity on each pin in the new socket. I have checked every
> single tracing that connects to every pin of the COPS socket, all test fine.
>
> The computer starts just fine with another I/O board.
>
> Symptoms, the computer powers on the second power is turned on. I don't
> have to push the power button. It just double beeps and gives I/O board
> error 52.
>
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-- 
Jason Perkins
313 355 0085

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