Dell Inspiron N5110: System time does not advance when unit

[David Farber]

On 3/26/2019 10:49 PM, whit3rd wrote:

On Monday, March 25, 2019 at 2:59:29 PM UTC-7, John Robertson wrote:
On 2019/03/25 10:28 a.m., David Farber wrote:
This Dell Inspiron N5110... The system time does not advance
when the unit is turned off.

Something is wrong with the on-board RTC - Real Time Clock.

You need to identify that chip or module and first see if its crystal is
damaged.

Another poster has suggested a circuit diagram
http://kythuatphancung.vn/uploads/download/22163_DELL_N5110.pdf

and the crystal would be X2101 and its associated components, R2101, C2101, C2102,
depicted on 'sheet 21 of 108' (see the label on lower left page corners) and connected
to pins A20 and C20 of the 'Cougar Point' big integrated circuit.

On page 99 of the schematic you can see the CMOS battery output labeled
as RTC_AUX_S5. I did a text search for that and it took me to page 27
which shows VBACKUP. There are two partial circuits there. One appears
to be for the CMOS battery backup and the other one, 3D3V_AUX_KBC,
appears to be the backup power supplied when the unit is turned on. Both
of these circuits point to EC GPIO72. Regarding the RTC_AUX_S5 diagram,
there's an orange ellipse around the specifications for a resistor. It
says 10mW 0R0402-PAD-2-GP. Might that be a fusible link? Also, I see the
words "stuff" and "un-stuff" appearing frequently in the schematic. Are
those synonyms for install and remove?

Thanks for your reply.
--
David Farber
Los Osos, CA

 

[Adrian Caspersz]

On 26/03/2019 21:21, David Farber wrote:

I cosign on salvaging electronics and exercising the brain cells.

By the way, how is it the computer keeps perfect time once the time is
set and the power remains on? Shouldn't the time shown in the BIOS setup
screen begin to advance too once it's powered on?

The RTC is only read once on startup of the operating system, which then
maintains the increment of it's own internal counter. There is no
'write-back' if current OS time settings are left alone by the user.

The BIOS time itself not incrementing is the fault, I reckon the chipset
has got itself into a funny state and needs a reset which you haven't
yet done. I'd try finding the G2101 link I mentioned.

Interestingly, the ACER ASPIRE V5 471 has the same labelled jumper,
similar circuit (same original manufacturer) - and googling that
"G2101", it looks a known reset method for locked BIOS etc. That Acer
motherboard visually looks different, but the G2101 triangular pads were
located under the DIMM sockets. Maybe Dell is in a similar location.


--
Adrian C

 

[Adrian Caspersz]

On 27/03/2019 17:36, Adrian Caspersz wrote:

Interestingly, the ACER ASPIRE V5 471 has the same labelled jumper,
similar circuit (same original manufacturer) - and googling that
"G2101", it looks a known reset method for locked BIOS etc. That Acer
motherboard visually looks different, but the G2101 triangular pads were
located under the DIMM sockets. Maybe Dell is in a similar location.

http://1.bp.blogspot.com/-CNHXkSjj8VE/UNV1-52T3uI/AAAAAAAAAR0/CpxDrJtoCjc/s1600/Dell+5110.JPG

G2101 is down to the right of G2201 as indicated. You don't want to mess
with G2201, that's something else.

--
Adrian C

 

[David Farber]

On 3/27/2019 10:48 AM, Adrian Caspersz wrote:

On 27/03/2019 17:36, Adrian Caspersz wrote:

Interestingly, the ACER ASPIRE V5 471 has the same labelled jumper,
similar circuit (same original manufacturer) - and googling that
"G2101", it looks a known reset method for locked BIOS etc. That Acer
motherboard visually looks different, but the G2101 triangular pads
were located under the DIMM sockets. Maybe Dell is in a similar location.



http://1.bp.blogspot.com/-CNHXkSjj8VE/UNV1-52T3uI/AAAAAAAAAR0/CpxDrJtoCjc/s1600/Dell+5110.JPG


G2101 is down to the right of G2201 as indicated. You don't want to mess
with G2201, that's something else.

Hi Adrian,

Your above link to the picture of the G2201 location is correct. Please
note that it's on the opposite side of the motherboard where the CMOS
battery lives. After performing the reset, I went into the BIOS setup
menu and set the time and date. Since then, the displayed time is now
accurate even after being powered off and then powered back on again.
This just goes to show you that removing the CMOS battery does not
necessarily reset whatever it was that needed resetting. (At least for
this computer)

Thanks to everyone for all your fantastic support!!!

--
David Farber
Los Osos, CA