Intermittent start-up - 2mm makes a difference

  • Thread starter Thread starter sandy
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sandy

Computer would randomly boot up and randomly turn off. I cleared the
cmos and turned on the machine with a screwdriver to make sure the
problem was not in the switch. Reconnected the switch and tested
several more times, worked like a charm. So I put the hard drive and
cd unit back in and when it is pressed all the way down, computer
doesn't start. If I put it within 2mm of all the way down, computer
starts.

I figure the hard drive unit is pressing on something, but I have
moved every cable and every wire in the vicinity. I cannot see
anything that would make a difference.

My question is: Is there something else I should be thinking of at
this point? Am I overlooking something obvious?

Thanks for any suggestions.
 
Computer would randomly boot up and randomly turn off. I cleared the
cmos and turned on the machine with a screwdriver to make sure the
problem was not in the switch.
Click to expand...

So at this point the machine was intact, or you had the hard
drive and CD out of it? When shorting with the screwdriver,
the system always turned on fine and never randomly turned
off?

Reconnected the switch and tested
several more times, worked like a charm. So I put the hard drive and
cd unit back in and when it is pressed all the way down, computer
doesn't start. If I put it within 2mm of all the way down, computer
starts.
Click to expand...

It seems as though you just have an intermittent switch.
Since most switches on modern cases are depressed by an
additional mechanical front consisting of a plastic button
and either a spring or springy piece of plastic, you might
remove the case front bezel and examine these parts to make
sure there isn't something cracked or broken off. With the
case frame behind the front bezel exposed, you can also try
directly pressing the switch to see if the switch itself is
the problem.

I figure the hard drive unit is pressing on something, but I have
moved every cable and every wire in the vicinity. I cannot see
anything that would make a difference.

My question is: Is there something else I should be thinking of at
this point? Am I overlooking something obvious?
Click to expand...

Playing odds, it is most likely the switch. There might be
a slim chance that the PSU is malfunctioning, but to get
this result it is far less likely. If the system behaves
normally when shorting with the screwdriver, that isolates
the problem to the switch or the switch wires.

You didn't tell us much about the system (for example
whether the case is OEM with a special wiring harness for
the front panel or if it's a pretty standard pinout,
connector, and switch. If the latter, you might be able to
take the switch (with wires and connector) to a local
mom-n-pop computer shop and get a replacement.
 
sandy said:
Computer would randomly boot up and randomly turn off. I cleared the
cmos and turned on the machine with a screwdriver to make sure the
problem was not in the switch. Reconnected the switch and tested
several more times, worked like a charm. So I put the hard drive and
cd unit back in and when it is pressed all the way down, computer
doesn't start. If I put it within 2mm of all the way down, computer
starts.

I figure the hard drive unit is pressing on something, but I have
moved every cable and every wire in the vicinity. I cannot see
anything that would make a difference.

My question is: Is there something else I should be thinking of at
this point? Am I overlooking something obvious?

Thanks for any suggestions.
Click to expand...


Likely a bad joint on a PCB (mobo or hdd), or perhaps a dodgy cable.


NT
 
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