Old Thinkpad needs help

[pgx]

I was called to look at an old Thinkpad 755CX. The POST would go as
far as displaying the memory size (40,460kb) then restarted, repeating
endlessly. While trying to get into the BIOS (without reading the
book), it booted!. Everything looked normal. Turned off and rebooted
- the same thing. No particular key combination worked, but at some
point it booted.

After reading the manual, found that F1 on startup should get into
diagnostics, but this didn't work - just the same endless reboot from
memory test.

There were no beep codes or screen dispays to indicate a problem.

Any thoughts?

This is obviously an old friend, rather than a valuable piece of
hardware, but if there is something easy, the owner would be happy.

Phil

 

[Grinder]

I was called to look at an old Thinkpad 755CX. The POST would go as
far as displaying the memory size (40,460kb) then restarted, repeating
endlessly. While trying to get into the BIOS (without reading the
book), it booted!. Everything looked normal. Turned off and rebooted
- the same thing. No particular key combination worked, but at some
point it booted.

After reading the manual, found that F1 on startup should get into
diagnostics, but this didn't work - just the same endless reboot from
memory test.

There were no beep codes or screen dispays to indicate a problem.

Any thoughts?

Bad capacitors? I'm not trying to sound like a seasoned diagnostician,
mind you, it's just that I've had the seem behavior in a desktop. A
physical inspection of the mainboard turned up a number of domed, and a
few vented, capacitors.