jwd@sas.UUCP (John W. DeBoskey) (02/23/90)
Hello,
I have a true blue ibm pc/xt which is now very dead. I've had it
for many years and it's seen alot of service(and abuse). Well, over
the past month or so, it's been taking parity errors almost continuously
and sometimes telling me that rom at addr xxx is bad, where xxx is
usually the addr of my hard disk rom.
Well, a couple of days ago, it quit for good. I turn it on and
it sits there. No POST. No nothing.
So, I took it apart, removed all socketed chips, cleaned the chips
and the sockets and replaced them. I've made especially sure that
everything was seated tightly.
I put a volt meter on the cpu. Powergood measures .149 volts.
Powergood at the power supply measures 5.28 volts. I don't have
a motherboard schematic for this machine, so I can't trace it
down. Could someone either send me a copy(I'll pay) or send me
the chip and pin numbers?
I measured the voltage on the address lines. Addr0 thru 8 all
measured 1.49 volts. To me this is messed up. Any comments? All the
rest measured 0.149 volts. From the looks of things, I don't think
my CPU is starting up. I've tried a 2nd CPU, but that made no difference
at all.
If anyone could help me with the schematic, I'd really appreciate
it. Any and all help hints are readily taken also.
Thanks for the time!
John W. De Boskey
jwd@sas.UUCP (w) rti.rti.org!sas!jwd (919) 677-8000 x6915
jwd@baggins.UUCP (h) mcnc.mcnc.org!baggins!jwd (919) 481-1057 (preferred)