Dell Inspiron 17R 3721 (LA-9102P) - No power on

PL300 = 401k ohms
0v / 0v

PU300
1 = 0 / 0
2 = 0 / 0
3 = 0 / 0
4 = 0 / 0
5 = 0 / 0
6 = 0 / 0
7 = 0 / 0
8 = 0 / 0
9 = 18v / 18v
10= 0 / 0
11= 5.1v /5.1
12= 5.1v / 5.1
13= 5.1v / 5.1
14= 0 / 0
15= 0 / 0
16= 0 / 0
17= 0 / 0
18= 4.7v / 4.7
19= 0 / 0
20= 0 / 0

Power on measurements.
Measure the voltages on pins 6, 9, 14, 16, 27, 37, 95, 100, 106, 107, 110, 112, 116, 124, 127 of KBC
Measure the voltages on KBC pin 114 in the following cases:
at power off
with pressed power on
at power on.

board only consumes 0.02A after power button
before / after pwr button

6 = 0 / 0
9 = 3.3 / 3.3v
14 = 0 / 0
16 = 3.3 / 3.3v
27 = 0 / 0
37 = 3.3 / 3.3v
95 = 0 / 0
100 = 0 / 3.3v
106 = 0 / 1.9
107 = 3.3 / 3.3
110 = 3.3 / 3.3
112 = 3.3 / 3.3
116 = 0 / 3.3
124 = 1.8 / 1.8
127 = 0 / 0.2

Pin 114 KBC
power off = 3.3v
pressed power button = 0.4v
power on = 3.3v

Measure the voltages to ground on pins 67, 115 of KBC chip.

Measure the voltage to ground on pin 106 of KBC chip in the following cases:
a) Power button released.
b) Power button pressed.

67 = 3.3 / 3.3
115 = 3.3 / 3.3

pin 106
pwr button pressed (hold down) = 3.4mV
released = 1.9v

Measure the voltage to ground on pin 12 of KBC chip in the following cases:
a) Before pressing to the power button.
b) After pressing to the power button.

pin 12

before = 0
after = 140mV

Replace the bios and remember to save the old one.
The KBC and / or the PCH are probably damaged.

Do you mean BIOS image or the actual chip?

I was reading this thread at badcaps about a similar Dell model 3521 that has the same symptoms (Very low power consumption, white LED on etc). The +3VS was not being generated, this is same on my board. I dont know if this has anything to do with the problem?

https://www.badcaps.net/forum/showthread.php?t=68748

QZ7 not making +3vs on my board

Your laptop does not stop before +3VS voltages are generated.

ok, i noticed +3VS provides lot of power to PCH. I thought maybe that was issue, no power to PCH so it not send PM_SLP signals with +3VS only being 0.7v.

Shall i programme new BIOS image or replace bios chip?

Try only to program a new bios (ATTENTION program only the bios for EC / KBC).

the 128kb image? with SAS programmer.

I download file from sualaptop365 and KBC file is 2mb? and main bios is only 4mb.

I will be away until weekend now untill i can report back. thank you for your contribution so far.

Exactly, you have to use the 2mb file.

Hi, sorry for the delay.

I programmed the 2mb bios file and still no change

Both BIOS chips (UH2 and UH6) are MAIN BIOS in this case. EC BIOS is stored in the internal memory of KBC chip.

Use the SAS programmer and reflash the KBC chip (KB9012) with 128kB file. Don't forget to save the old dump.

ok, i use SAS programmer and program KBC with 128kb file from vinafix and still no change. Also tried original 128kb file again after flashing 2mb UH2 and no change.

is it worth flashing the 4mb bios UH6?

there is similar problem in below thread to a Dell board, the board has same symptoms.
https://www.badcaps.net/forum/showthread.php?t=68748

Remeasure the voltages to ground on pins 106, 114 of KBC chip in the following cases:
a) Power button released.
b) Power button pressed.

released / pressed

106 = 0 / 0v (pwr button held down) - 1.9v after pressing.
114= 3.3 / 0.4V (pwr button held down) - 3.3v after pressing

Measure the voltages to ground on both pins of quartz YH1. It is located near the PCH chip.