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Hello!

The components are as follows:
A= Capacitor 100nF/6.3V, package 0201
B= Resistor 2.2Ω/5%, package 0402
Obrazek

These two components may be responsible for backlight flickering. I suggest you to replace both.

Re: HP Elitebook 840 G1 No Display

przez matic 26 marca 2024, 22:36 • NAPRAWA LAPTOPÓW

- Measure the voltage to ground on pin 3 pf chip U6600, while the machine is booted into BIOS and also OS.
- Measure the voltage to ground on the coil L6600, while the machine is booted into BIOS.

The jumpers on this board are actually part of the copper strip on the PCB. The only way to open them is to cut the copper traces.
Remove the capacitors PC211, PC230 from the board and post a clear pictures of PJP3, PJP4 areas of the board.

Now the question is whether to buy PCH, Allegro or is it worth taking the risk on Aliexpress? It's your choice, but make sure to buy a brand new PCH. The used (refurbished) one may be "pulled" from the board with a BootGuard enabled and such a PCH will not work even though it's functional...

Measure the voltage to ground on pin 96 of KBC chip with and without battery connected (power supply connected all the time).

psikus123 napisał(a):3,3V z obu stron
The copper path on PCB between pin 1 of coil L6004 and pin 3 of battery connector is damaged. Restore the connection with a thin jump wire.

psikus123 napisał(a):Jest dostępny schemat do tej platformy?
Currently unavailable.

All transistors are damaged. That's quite strange. It's usually damaged only one of them. You can check them out of the board. They are dual transistors in one package: https://www.elvikom.pl/pictures/thumbs/00063053.jpg I did a short circuit test on +vin 19.5v 1A. I do not recommend to perform a s...

lomcio napisał(a):PJ1002 16om
This resistance seems completely normal to me.
The resistances on all other coils also seems normal.

If there was no picture, the GPU or CPU may be guilty, but it's impossible to diagnose without replacing the damaged PCH chip or transferring the GPU / CPU to another board.

Przeprowadziłem próbę zwarciową, zasilanie dałem na PJ302, i od razu po podłączeniu zasilacza zwarcie, prąd 2-3 A przy napięciu około 1V, zaczął się grzać PCH. Hello! Yes, the PCH chip is definitely damaged. PJ1002 +1.0V VSDGPU Are you sure there is a short circuit to ground on this jumper? What is...

Measure the voltages to ground on both pins of coil L6004 with the power supply connected only (without battery).

Please, post a clear picture of marked area of the board.
Obrazek

BIOS DUMP Marka i model: Lenovo V14-IIL Platforma (z rewizją płyty): LCFC GS44D/GS54D , NM-C711 , Rev: 1.0 APU: Intel Core i5-1035G1 (SRGKG) EC/KBC: Lenovo IT8227E-128 BIOS IC= UC702: Winbond W25Q128JVSQ (128Mbit = 16MB) Uwagi 1: A BIOS dump with on-board RAM memory disabled - the board works with ...

- Measure the resistance to ground on pin 3 of battery connector (with the power supply and battery disconnected of course).
- Measure the voltages to ground on both pins of resistor R3004 with the power supply connected only (without battery).

Hello!

Measure the voltages to ground on all pins of battery connector with and without battery connected (power supply connected all the time).

Remove the transistor PQ601 from the board and check, if the transistor PQ600 still heats up with the battery + power supply connected.

Was this measurement taken with the RAM and CPU connected?
If so, test the board with another RAM.

krzysztof000 napisał(a):Gdzie na tej płycie znaleźć główną kość biosu
Hello!
It's the chip U1:
Obrazek

krzysztof000 napisał(a):czy będę mógł ją zaprogramować svodem tylko za pomocą jego adaptera?
Yes, as long as you have the 8x6mm WSON-8 adapter.

At least one of the transistors PQ4001, PQ4004, PQ4005 is damaged for sure. Measure the resistance between pin 1 and pin 2 of each of these transistors. If this resistance is low (less then 10Ω) on one of the transistors, the corresponding transistor is damaged - remove it from the board and remeasu...

Measure the resistances on all coils in reference to the "+VIN" side of resistor PR1008.

Wylutuj jeden koniec diod D101 i D102 one są połączone równolegle, sprawdź czy któraś niema zwarcia Measure the resistance across the capacitor C101. If the resistance is high (in kΩ range or greater), both diodes are fine almost for sure. Jeżeli będą sprawne pozostaje sprawdzić tranzystor Q1 If th...

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