Re: 2 PCs not starting up properly nor shutting down
- From: w_tom <w_tom1@xxxxxxx>
- Date: Sat, 17 Nov 2007 19:53:17 -0800 (PST)
Those voltages listed as "without touching case's power switch" and
"pressing the case's power switch" are measuring same thing. Wires
have voltages even before power switch is pressed: "when computer is
powered off". A turned off computer is still powered. But what are
those voltages when power is supposed to be off - before power switch
is pressed - when green wire is above 2 volts? A secondary question
since we are in pursuit of a primary suspect.
When green wire is below 0.8 volts, then both lists are same: "when
computer is powered on". Sidenote: that green wire voltage should
be well below 0.8 volts - typically 0.2 volts. A secondary
(stability) problem maybe addressed later. Onward in pursuit of the
primary suspect.
Important voltages are fine and perfect. Power supply system
(including the gray wire) is telling computer to operate. But computer
does not.
Normally a tech might plug in a diagnostic board to read a BIOS
error code. An error message might also appear on the monitor. But
your monitor is not displaying anything. Most people have no
diagnostic board. No problem. What is minimally required to power up?
Remove AC power cord. Remove everything from computer except
motherboard, speaker, CPU, power switch, and power supply. That means
no keyboard, no memory, no video controller, no mouse, no drives, etc.
Everything else disconnected from motherboard. Now reconnect AC power
cable.
Before power switch is pressed, that green wire will measure
something above 2 volts. When power switch is pressed, the green wire
will drop to near zero and gray wire will rise above 2.4 volts. Then
motherboard's BIOS (program) should execute. It will find no memory
and beep an error code on the speaker (or beeper soldered to
motherboard).
We knew power switch and power supply system are functional (even
with a marginal green wire voltage) from previous and current
measurements. If speaker does not beep, then suspect only motherboard
or CPU. CPUs are almost never damaged since so many motherboard
functions protect it. CPU damage typically means motherboard caused
its failure. Primary suspect identified.
If speaker does beep, then motherboard and CPU are functional.
Suspects are those other peripherals - a most likely suspect being the
video controller.
Remove AC power cord. Install only the video controller. Reconnect
power cord. Perform same test. Does speaker still beep? If not,
primary suspect identified. If yes, repeat for other peripherals (but
no memory) until something causes that speaker to not beep.
On Nov 17, 3:47 pm, Erik <E...@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
OK, so here are some more numbers. Power supply (including 4 pin 12 V.
connector) hooked up to MB, graphics card and 1 drive installed.
Power supply switch in ON position. Power supply fan comes on, CPU fan comes
on, graphics card fan comes on, HD starts spinning.
Without touching the case's power switch:
Purple: 5.17 V
Green: 0.78 V
Gray: 5.15 V
Orange: 3.43 V
Red: 5.15 V
Yellow: 12.10 V
Pressing the case's power switch:
Purple: 5.17 V
Green: 0.78 V
Gray: 5.15 V
Orange: 3.43 V
Red: 5.15 V
Yellow: 12.10 V
As you can see, the voltages are the same.
I checked the operation of the case's power switch with the Ohm meter, and
the switch is OK. The same for the reset switch.
In the message that you referred to in your first reply, you say that the
voltage on the green wire should be "well below 0.8 V when the power switch
is pressed". I take it my 0.78 V is not low enough then?
I don't have much more time to test anything today; as I go to work in less
than an hour. However, your thoughts would be very much appreciated (and I
will read them today at work); so please don't hesitate to send me any other
tips about things that I can test; and I'll get to that tomorrow.
- Follow-Ups:
- References:
- 2 PCs not starting up properly nor shutting down
- From: Erik
- RE: 2 PCs not starting up properly nor shutting down
- From: Andrew E.
- Re: 2 PCs not starting up properly nor shutting down
- From: w_tom
- Re: 2 PCs not starting up properly nor shutting down
- From: Erik
- Re: 2 PCs not starting up properly nor shutting down
- From: w_tom
- Re: 2 PCs not starting up properly nor shutting down
- From: Erik
- 2 PCs not starting up properly nor shutting down
- Prev by Date: Re: Problem reinstalling Windows - think it's a hardware issue
- Next by Date: Re: Problem reinstalling Windows - think it's a hardware issue
- Previous by thread: Re: 2 PCs not starting up properly nor shutting down
- Next by thread: Re: 2 PCs not starting up properly nor shutting down
- Index(es):
Relevant Pages
|
