'not well' Osborne 1 mk 2

From: Tony Duell <ard_at_p850ug1.demon.co.uk>
Date: Sat Jan 17 16:53:37 2004

>
> Just a quickie folks,
>
> Does anyone have the power cable pinouts for the Osborne 1 motherboard? Got
> one here from Kevan that doesn't boot at all - consistent garbage on the
> nice'n'bright screen. Before I start further messing with the beast I want
> to make sure it's getting enough juice. Suppose I can always check the CPU
> and RAM chips for +5V couldn't I - it's been powered up in this condition in

Yes, that's what I'd do. Check the 5V line at a known chip (CPU, or a TTL
device). In a machine of this type, there'll only be one 5V line (unlike
in my 11/45 where there are several, from separate PSU bricks...).

I don't know what the RAMs used are, but if they're 3-rail types, like
4116s, you should check the other supplies there too.

If the PSU lines look good, then check that the CPU is getting a clock
signal. Look also for activity (changing singals) on the address and data
lines from the CPU.

-tony
Received on Sat Jan 17 2004 - 16:53:37 GMT