OT Startup problem

This is probably an emachine T2984 hardware oroblem, not XP, but there
are so many helpful people here I thought I'd try here first.

The computer starts up by itself, no button press, when the UPS is turned
on. Screenful of error messages, ending with keyboard error. Date and
time are totally wrong.

I rashly assume it is the motherboard/CMOS battery. After some research
with Google it seems to be a CR2032. Nothing about it in the computer
documentation. I bought some and plan to replace it later.

Does this sound right?

Anything I should know about changing the battery? I will try to ground
myself on the computer case and of course turn the computer off.
Anythuing else? I've not dome this for a decade or so.

TIA




--
I love a good meal! That's why I don't cook.

KenK wrote:
This is probably an emachine T2984 hardware oroblem, not XP, but there
are so many helpful people here I thought I'd try here first.

The computer starts up by itself, no button press, when the UPS is turned
on. Screenful of error messages, ending with keyboard error. Date and
time are totally wrong.

I rashly assume it is the motherboard/CMOS battery. After some research
with Google it seems to be a CR2032. Nothing about it in the computer
documentation. I bought some and plan to replace it later.

Does this sound right?

Anything I should know about changing the battery? I will try to ground
myself on the computer case and of course turn the computer off.
Anythuing else? I've not dome this for a decade or so.

TIA

I would recommend a more careful check than this.

First off, there are some machines that have a power recovery
setting. It can be "machine on" after the power recovers. It
can be "machine off" (the default I use for all machines here).
It can also be "last state", which means if the machine was on
at the time the power last went off, the machine will turn on
automatically when power is restored.

Now, if the CMOS battery was bad, the settings were corrupted,
but they still passed the checksum test, it's possible the
thing could switch on like that.

*******

However, a more concerning case, is what happened to my P2B-S.
An IDE cable got bumped out of place when I was working
on something else inside the machine. Only half the IDE
pins were touching. This caused stress and electrical loading
on the Southbridge, causing the power on circuit to be
triggered as soon as the AC was applied. Shutting the machine
down, and inserting the cable properly, fixed it. I thought
at first, it was going to be damaged.

If you had a defective hard drive, in theory it could
present the same symptoms. Maybe this would happen if the
+5V was disconnected from the drive or something (bad
wire on Molex power cable).

So while the most likely explanation (replace CR2032)
is the correct one, you might also have to consider
whether something is electrically loading the
Southbridge like happened in my case, and that
is what is turning on the computer.

You'll know for sure, after replacing the CR2032
and applying AC power again. If the behavior is
still there, try to enter the BIOS and correct
the settings in the power management section.

*******

Be careful with the CR2032. Some sockets for those, are
real easy to work with. Others are terrible. I had one
poster who *ripped the CR2032 socket off the motherboard*.
Don't do that :-) On the good ones here, you pinch the clip
on one side of the socket, and the battery should be able to be
rocked out of place. Inserting the new one is really easy
by comparison.

The power should be *off* when you do that. The battery
will hop out of the socket, and bounce all over the place.
It can easily short out power points on the motherboard.
Make sure the PC is unplugged, before you begin. An
antistatic strap and alligator clip are recommended,
but if you're careful to bring yourself to the
same potential as the chassis, you probably won't
blow it up just handling the battery. The danger is
marginally greater, if you handle the 3-pin header
with the "Clear CMOS" jumper on it. You should not
need to mess with the jumper at all, while changing
out the battery. It should drain flat, by the time
you can maneuver the new battery into place.

One way to bring the chassis to the same potential as
you, is to wear short pants, and rest the PC chassis,
door side up, facing you. Your skin contact against
the chassis, reduces ESD risks. Make sure all your
tools and supplies are next to you, before you begin.

The (+) faces up, and there's really only one
way to fit the battery anyway. Verify the (+)
is on top, before you remove it. A good battery
measured 3.1V or slightly more. A bad battery is
2.3V or less. The battery will drain from 2.3V to
zero volts, in about three or four weeks, so after
the machine presents symptoms, the battery
will be completely flat a month from then.

Those batteries come in various sizes, and if it
isn't a CR2032, it could be thinner for example.
The part number always seems to be stamped on it,
so you should not have a problem verifying you
bought the correct one.

The modern CR2032 smell funny. The old ones didn't.
Chalk this up to low quality manufacturing lines
making these for $0.10 each. The old ones were
sealed well enough that the chemical smell
didn't escape.

I've never had one of those corrode or leak.
They're really the most benign battery I know of!

Paul

Paul wrote in news
KenK wrote:
This is probably an emachine T2984 hardware oroblem, not XP, but
there are so many helpful people here I thought I'd try here first.

The computer starts up by itself, no button press, when the UPS is
turned on. Screenful of error messages, ending with keyboard error.
Date and time are totally wrong.

I rashly assume it is the motherboard/CMOS battery. After some
research with Google it seems to be a CR2032. Nothing about it in the
computer documentation. I bought some and plan to replace it later.

Does this sound right?

Anything I should know about changing the battery? I will try to
ground myself on the computer case and of course turn the computer
off. Anythuing else? I've not dome this for a decade or so.

TIA

I would recommend a more careful check than this.

First off, there are some machines that have a power recovery
setting. It can be "machine on" after the power recovers. It
can be "machine off" (the default I use for all machines here).
It can also be "last state", which means if the machine was on
at the time the power last went off, the machine will turn on
automatically when power is restored.

Now, if the CMOS battery was bad, the settings were corrupted,
but they still passed the checksum test, it's possible the
thing could switch on like that.

*******

However, a more concerning case, is what happened to my P2B-S.
An IDE cable got bumped out of place when I was working
on something else inside the machine. Only half the IDE
pins were touching. This caused stress and electrical loading
on the Southbridge, causing the power on circuit to be
triggered as soon as the AC was applied. Shutting the machine
down, and inserting the cable properly, fixed it. I thought
at first, it was going to be damaged.

If you had a defective hard drive, in theory it could
present the same symptoms. Maybe this would happen if the
+5V was disconnected from the drive or something (bad
wire on Molex power cable).

So while the most likely explanation (replace CR2032)
is the correct one, you might also have to consider
whether something is electrically loading the
Southbridge like happened in my case, and that
is what is turning on the computer.

You'll know for sure, after replacing the CR2032
and applying AC power again. If the behavior is
still there, try to enter the BIOS and correct
the settings in the power management section.

*******

Be careful with the CR2032. Some sockets for those, are
real easy to work with. Others are terrible. I had one
poster who *ripped the CR2032 socket off the motherboard*.
Don't do that :-) On the good ones here, you pinch the clip
on one side of the socket, and the battery should be able to be
rocked out of place. Inserting the new one is really easy
by comparison.

The power should be *off* when you do that. The battery
will hop out of the socket, and bounce all over the place.
It can easily short out power points on the motherboard.
Make sure the PC is unplugged, before you begin. An
antistatic strap and alligator clip are recommended,
but if you're careful to bring yourself to the
same potential as the chassis, you probably won't
blow it up just handling the battery. The danger is
marginally greater, if you handle the 3-pin header
with the "Clear CMOS" jumper on it. You should not
need to mess with the jumper at all, while changing
out the battery. It should drain flat, by the time
you can maneuver the new battery into place.

One way to bring the chassis to the same potential as
you, is to wear short pants, and rest the PC chassis,
door side up, facing you. Your skin contact against
the chassis, reduces ESD risks. Make sure all your
tools and supplies are next to you, before you begin.

The (+) faces up, and there's really only one
way to fit the battery anyway. Verify the (+)
is on top, before you remove it. A good battery
measured 3.1V or slightly more. A bad battery is
2.3V or less. The battery will drain from 2.3V to
zero volts, in about three or four weeks, so after
the machine presents symptoms, the battery
will be completely flat a month from then.

Those batteries come in various sizes, and if it
isn't a CR2032, it could be thinner for example.
The part number always seems to be stamped on it,
so you should not have a problem verifying you
bought the correct one.

The modern CR2032 smell funny. The old ones didn't.
Chalk this up to low quality manufacturing lines
making these for $0.10 each. The old ones were
sealed well enough that the chemical smell
didn't escape.

I've never had one of those corrode or leak.
They're really the most benign battery I know of!

Paul


Thanks much as always.

I forgot to say, the computer starts and runs normally after I get that
screenful of errors. Just push the power button to both get rid of the
errors and shut the computer off, press again to start again and it
starts and runs normally. Then have to reset the time and date.

I'll hold off on changing the battery until you read this.


--
I love a good meal! That's why I don't cook.

KenK wrote:
Paul wrote in news
KenK wrote:
This is probably an emachine T2984 hardware oroblem, not XP, but
there are so many helpful people here I thought I'd try here first.

The computer starts up by itself, no button press, when the UPS is
turned on. Screenful of error messages, ending with keyboard error.
Date and time are totally wrong.

I rashly assume it is the motherboard/CMOS battery. After some
research with Google it seems to be a CR2032. Nothing about it in the
computer documentation. I bought some and plan to replace it later.

Does this sound right?

Anything I should know about changing the battery? I will try to
ground myself on the computer case and of course turn the computer
off. Anythuing else? I've not dome this for a decade or so.

TIA
I would recommend a more careful check than this.

First off, there are some machines that have a power recovery
setting. It can be "machine on" after the power recovers. It
can be "machine off" (the default I use for all machines here).
It can also be "last state", which means if the machine was on
at the time the power last went off, the machine will turn on
automatically when power is restored.

Now, if the CMOS battery was bad, the settings were corrupted,
but they still passed the checksum test, it's possible the
thing could switch on like that.

*******

However, a more concerning case, is what happened to my P2B-S.
An IDE cable got bumped out of place when I was working
on something else inside the machine. Only half the IDE
pins were touching. This caused stress and electrical loading
on the Southbridge, causing the power on circuit to be
triggered as soon as the AC was applied. Shutting the machine
down, and inserting the cable properly, fixed it. I thought
at first, it was going to be damaged.

If you had a defective hard drive, in theory it could
present the same symptoms. Maybe this would happen if the
+5V was disconnected from the drive or something (bad
wire on Molex power cable).

So while the most likely explanation (replace CR2032)
is the correct one, you might also have to consider
whether something is electrically loading the
Southbridge like happened in my case, and that
is what is turning on the computer.

You'll know for sure, after replacing the CR2032
and applying AC power again. If the behavior is
still there, try to enter the BIOS and correct
the settings in the power management section.

*******

Be careful with the CR2032. Some sockets for those, are
real easy to work with. Others are terrible. I had one
poster who *ripped the CR2032 socket off the motherboard*.
Don't do that :-) On the good ones here, you pinch the clip
on one side of the socket, and the battery should be able to be
rocked out of place. Inserting the new one is really easy
by comparison.

The power should be *off* when you do that. The battery
will hop out of the socket, and bounce all over the place.
It can easily short out power points on the motherboard.
Make sure the PC is unplugged, before you begin. An
antistatic strap and alligator clip are recommended,
but if you're careful to bring yourself to the
same potential as the chassis, you probably won't
blow it up just handling the battery. The danger is
marginally greater, if you handle the 3-pin header
with the "Clear CMOS" jumper on it. You should not
need to mess with the jumper at all, while changing
out the battery. It should drain flat, by the time
you can maneuver the new battery into place.

One way to bring the chassis to the same potential as
you, is to wear short pants, and rest the PC chassis,
door side up, facing you. Your skin contact against
the chassis, reduces ESD risks. Make sure all your
tools and supplies are next to you, before you begin.

The (+) faces up, and there's really only one
way to fit the battery anyway. Verify the (+)
is on top, before you remove it. A good battery
measured 3.1V or slightly more. A bad battery is
2.3V or less. The battery will drain from 2.3V to
zero volts, in about three or four weeks, so after
the machine presents symptoms, the battery
will be completely flat a month from then.

Those batteries come in various sizes, and if it
isn't a CR2032, it could be thinner for example.
The part number always seems to be stamped on it,
so you should not have a problem verifying you
bought the correct one.

The modern CR2032 smell funny. The old ones didn't.
Chalk this up to low quality manufacturing lines
making these for $0.10 each. The old ones were
sealed well enough that the chemical smell
didn't escape.

I've never had one of those corrode or leak.
They're really the most benign battery I know of!

Paul


Thanks much as always.

I forgot to say, the computer starts and runs normally after I get that
screenful of errors. Just push the power button to both get rid of the
errors and shut the computer off, press again to start again and it
starts and runs normally. Then have to reset the time and date.

I'll hold off on changing the battery until you read this.

You can take a multimeter reading off the top of the
battery, without removing it. Even a $20 Harbor Freight
meter will do (set it to Volts and use the Volt/Ohm holes).

Connect the black lead to a screw on the I/O plate
area on the back of the computer. Connect the
red lead to the top of the battery while the battery
sits in the socket. Then check to see if it has dropped
below 2.3V. For it to have a significant life, it
should be closer to 3V. As I indicated previously,
if it is getting close to flat (2.3V), it doesn't
take long to crash all the way to zero.

The CR2032 does not recharge, and you should not
attempt to recharge it. The datasheet only allows
1uA of current to enter the battery (as a charging
current), and the only reason even this amount of
current flow is defined, is because it's hard to
make a circuit that leaks less than that. The diode
right next to the battery is a Schottky, and 1uA
leakage (at an elevated temperature) is about
as good as they get.

Paul

In message , Paul
writes:
[]
Be careful with the CR2032. Some sockets for those, are
real easy to work with. Others are terrible. I had one
[]
The (+) faces up, and there's really only one
way to fit the battery anyway. Verify the (+)
is on top, before you remove it. A good battery
measured 3.1V or slightly more. A bad battery is
2.3V or less. The battery will drain from 2.3V to
zero volts, in about three or four weeks, so after
the machine presents symptoms, the battery
will be completely flat a month from then.

Also be careful not to get anything - even finger grease - across the
seal on the cell. It'll prolong its useful life.

Those batteries come in various sizes, and if it
isn't a CR2032, it could be thinner for example.
The part number always seems to be stamped on it,
so you should not have a problem verifying you
bought the correct one.

And the part number, rather pleasingly, gives the dimensions: 20mm
across, 3.2mm thick (or 2.4, or 1.6).

--
J. P. Gilliver. UMRA: 1960/1985 MB++G()AL-IS-Ch++(p)Ar@T+H+Sh0!:`)DNAf

Where [other presenters] tackle the world with a box of watercolours, he
takes a spanner. - David Butcher (on Guy Martin), RT 2015/1/31-2/6

In message , Paul
writes






*******

Be careful with the CR2032. Some sockets for those, are
real easy to work with. Others are terrible. I had one
poster who *ripped the CR2032 socket off the motherboard*.
Don't do that :-) On the good ones here, you pinch the clip
on one side of the socket, and the battery should be able to be
rocked out of place. Inserting the new one is really easy
by comparison.

The power should be *off* when you do that. The battery
will hop out of the socket, and bounce all over the place.

Just a tip when replacing CR2032 batteries:

Stick a couple of inches of sticky tape (duct tape is a good choice) on
the battery so you have something to pull on to lift it out of its
socket. A similar bit of sticky tape often helps when inserting a new
battery.




--
Ian