Image of Bottom of Motherboard, HP Pavilion XT155 laptop

SNIP

https://www.mynaq.org/hp-compaq-nx90...75-dakt7imb8d4

The board in question has an ALI chipset. Does yours have an ALI chipset
or are we on a wild goosechase ? It uses an ALI M1535+ and it has an ATI
GPU fitted to it.

You can see an RTC battery in this picture, but I can't make
out the notation on the battery. There is a button that looks
like "Clear CMOS" button nearby.

https://www.mynaq.org/image/cache/ca...56-800x600.JPG

There's just no warm and fuzzy feeling here, no "positive ID".

You have a better idea what's in there than I do.

Paul

Hi Paul,

I don't know at this moment if this board has an ALI chipset.

I saved all the images. I don't need to know the battery number, just
it's location on the board which seems to be on the bottom of board.

Some of the ports (external monitor, serial, parallel) locations seem to
match this laptop.

I will examine the images very carefully before I make any conclusions.

Hi Paul,

UPDATE:

Thanks to you and that link to the images, which is a MATCH
to my laptop, I was able to cut (dremel tool) an openings at the
CMOS battery location and remove the battery (ML1220 rechargeable).

Note: That "button switch" near battery is a "Reset" (not for clearing
CMOS memory).

With the battery removed, I am going to wait 24 hours or more for CMOS
memory to clear (did that on other HP laptop years ago). I measured the
battery voltage, it was around 2 V. Note: CMOS battery may have run
down to a low voltage, corrupting CMOS memory. Then charging that
battery (AC adapter plugged in (Main battery was defective & removed))
has "sustained" the corrupted CMOS memory.

After a day or so, I will hook up wires and use external 3VDC source
to see if this laptop will boot up without those 4 short beeps from POST
before I install a new battery (have to order one).

I am hoping that the CMOS memory became corrupted like it happened
on a different model HP I have years ago.

Again, Thank You Very Much for your help, John

On Thu, 20 Aug 2020 at 13:11:04, wrote:
[]
With the battery removed, I am going to wait 24 hours or more for CMOS
memory to clear (did that on other HP laptop years ago). I measured the

You could short the cell terminals (e. g. put in a coin rather than a
coin cell!) on the mobo once you've removed the cell, which would
probably clear/reset it sooner. (With no power - mains or battery -
connected of course! And remember to remove the short/coin before
applying any power!)
[]
--
J. P. Gilliver

J. P. Gilliver (John) wrote:
On Thu, 20 Aug 2020 at 13:11:04, wrote:
[]
With the battery removed, I am going to wait 24 hours or more for
CMOS
memory to clear (did that on other HP laptop years ago). I measured the

You could short the cell terminals (e. g. put in a coin rather than a
coin cell!) on the mobo once you've removed the cell, which would
probably clear/reset it sooner. (With no power - mains or battery -
connected of course! And remember to remove the short/coin before
applying any power!)
[]

Which includes removing the wall adapter, the main battery pack,
the coin cell, *then* short out the socket as a means to
drain the last remaining supply (a tiny ceramic cap sitting
on the VBAT line). The purpose of the tiny ceramic cap is
to provide instantaneous current when a counter ticks
in the RTC well.

You should not short out the coin cell socket while power
is available. There is a charging circuit connected to the
coin cell, and we don't want to be shorting that out
while it's attempting to charge the cell. With all power
removed, it won't be attempting anything.

I'm expecting, if it is an LR20xx or ML20xx rechargeable cell,
that's not going to be available at the watch repair store
(a supplier of batteries). I don't even know if the Geek Squad
would have something like that. Locating one should be more
annoying than finding a CR20xx.

Paul

On 8/20/2020 7:41 PM, Paul wrote:

I'm expecting, if it is an LR20xx or ML20xx rechargeable cell,
that's not going to be available at the watch repair store
(a supplier of batteries). I don't even know if the Geek Squad
would have something like that. Locating one should be more
annoying than finding a CR20xx.

Paul

Paul:


Not hard at all to find If you know where to look ;-)

https://www.digikey.com/products/en/...ry/91?k=ML1220

John


--

J. P. Gilliver (John) wrote:
On Thu, 20 Aug 2020 at 13:11:04, wrote:
[]
With the battery removed, I am going to wait 24 hours or more for
CMOS
memory to clear (did that on other HP laptop years ago). I measured the

You could short the cell terminals (e. g. put in a coin rather than a
coin cell!) on the mobo once you've removed the cell, which would
probably clear/reset it sooner. (With no power - mains or battery -
connected of course! And remember to remove the short/coin before
applying any power!)
[]

Which includes removing the wall adapter, the main battery pack,
the coin cell, *then* short out the socket as a means to
drain the last remaining supply (a tiny ceramic cap sitting
on the VBAT line). The purpose of the tiny ceramic cap is
to provide instantaneous current when a counter ticks
in the RTC well.

You should not short out the coin cell socket while power
is available. There is a charging circuit connected to the
coin cell, and we don't want to be shorting that out
while it's attempting to charge the cell. With all power
removed, it won't be attempting anything.

I'm expecting, if it is an LR20xx or ML20xx rechargeable cell,
that's not going to be available at the watch repair store
(a supplier of batteries). I don't even know if the Geek Squad
would have something like that. Locating one should be more
annoying than finding a CR20xx.

Hi Paul,

FINAL UPDATE:

Since the main battery was defective, only the case of the
battery (insides was removed some time ago), I decided to do
what I did with that other HP laptop (different model). I put
two AA akaline batteries in that case with a diode to prevent
charging those AA batteries (non-chargeable). Ran fine wires
to CMOS battery holder & soldered wires to contacts.

In order to bootup this laptop, I was unable to use F2 for
BIOS settings due to a PASSWORD prompt (NO clue what
the password is). However, I also had a diagnostics option (F10) and used
that to get defaults put into CMOS after a report that "CMOS checksum was
bad".

I am now able to use this laptop again.

Once more, Thank You for all your help, John

John Dulak wrote:
On 8/20/2020 7:41 PM, Paul wrote:

I'm expecting, if it is an LR20xx or ML20xx rechargeable cell,
that's not going to be available at the watch repair store
(a supplier of batteries). I don't even know if the Geek Squad
would have something like that. Locating one should be more
annoying than finding a CR20xx.

Paul

Paul:


Not hard at all to find If you know where to look ;-)

https://www.digikey.com/products/en/...ry/91?k=ML1220


John

I'm talking about sourcing the right item locally,
if you seek to reduce downtime while DIY repair.

Yes, you can get anything you want from the Internet.

The pictures in this case, do not inspire confidence,
and I'd prefer to see nice sharp detail before I
run off and buy one.

I'm a measure twice, cut once kinda guy :-) Lots
of procedures here, I hold off on doing them
until I have materials, and a Plan B.

Paul