20 May
2014
20 May
'14
7:06 p.m.
Looks like I'll have to head down south and grab some of my test gear. Been meaning to
do that anyway.
Sent from my iPhone
On May 20, 2014, at 17:36, ard at p850ug1.demon.co.uk (Tony Duell) wrote:
The PSU seems to operate fine. I get steady green on the power and can hear
the drive spin up.
It's best not to assume anything (I've wasted hours looking for faults in
one area of a machine ahving assumed another part was correct becuase it
seemed to be, only to find that thet's where the problem really was)
Start with a voltmeter and check each supply votlage at the motehrboard
connector. Also check the power OK line , which I think, should be a TTL
high level when the machine is operational.
If all those are OK, then I would check for activity (toggling) on the
important signals -- the addres and data lines, ROM chip sleect, RaM
address, RAS/ and CAS/ and so on. Jsut to get some idea if anything is
working, This will pick up problems like no CPU clock, or the system
stuck i nthe reset state.,
-tony