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Re: Samsung np350v QCLA4 LA-8861P - brak napięcia na Vcc kości bios
by Google Adsense [BOT] • 8 August 2024, 17:08
#2 Re: Samsung np350v QCLA4 LA-8861P - brak napięcia na Vcc kości bios
by matic • 9 August 2024, 07:20
Hello!
To enable the +3VS voltage, the signal "SUSP#" should be at high state. This signal is issued by the KBC chip on pin 116. This signal opens the transistor Q6A and consequently pulls the "SUSP" signal to low state. Because the "SUSP" signal is at low state, the transistor Q10A is closed and the power transistor Q29 is opened by the output voltage from the voltage divider formed by resistors R409 and R412.
So, first check if you get a high state (3.3V) on pin 116 of KBC chip after pressing to the power button.
To enable the +3VS voltage, the signal "SUSP#" should be at high state. This signal is issued by the KBC chip on pin 116. This signal opens the transistor Q6A and consequently pulls the "SUSP" signal to low state. Because the "SUSP" signal is at low state, the transistor Q10A is closed and the power transistor Q29 is opened by the output voltage from the voltage divider formed by resistors R409 and R412.
So, first check if you get a high state (3.3V) on pin 116 of KBC chip after pressing to the power button.
#4 Re: Samsung np350v QCLA4 LA-8861P - brak napięcia na Vcc kości bios
by matic • 12 August 2024, 07:20
Measure the voltages to ground on pins 37, 67, 101, 110, 112, 115, 124 of KBC chip.
Measure the voltages to ground on pins 106, 114 of KBC chip in the following cases:
a) Power button released.
b) Power button pressed.
Now disconnect the power supply, wait abut two minutes, reconnect the power supply and perform the following measurements:
Measure the voltages to ground on pins 6, 13, 14, 95, 100, 107, 116, 127 of KBC chip in the following cases:
c) Before pressing to the power button (machine turned off).
d) After pressing to the power button (power LED is turned on).
Measure the voltages to ground on pins 106, 114 of KBC chip in the following cases:
a) Power button released.
b) Power button pressed.
Now disconnect the power supply, wait abut two minutes, reconnect the power supply and perform the following measurements:
Measure the voltages to ground on pins 6, 13, 14, 95, 100, 107, 116, 127 of KBC chip in the following cases:
c) Before pressing to the power button (machine turned off).
d) After pressing to the power button (power LED is turned on).
#7 Re: Samsung np350v QCLA4 LA-8861P - brak napięcia na Vcc kości bios
by Yamaiko • 13 August 2024, 09:37
Okazuje się, że układ UCL1 jest uszkodzony. Brak sygnału o częstotliwości 25Mhz na nóżce 9 powoduje że laptop się nie uruchamia. Odlutowałem kondensator na nóżce 14 i laptop ożył. Zmierzyłem ten kondensator i ma 25uF a powinien mieć według schematu 2.2uF. Możliwe, że przez pojemność układ UCL1 pracuje niestabilnie ?
#8 Re: Samsung np350v QCLA4 LA-8861P - brak napięcia na Vcc kości bios
by carrneiro • 13 August 2024, 15:11
Yamaiko wrote:Okazuje się, że układ UCL1 jest uszkodzony. Brak sygnału o częstotliwości 25Mhz na nóżce 9 powoduje że laptop się nie uruchamia. Odlutowałem kondensator na nóżce 14 i laptop ożył. Zmierzyłem ten kondensator i ma 25uF a powinien mieć według schematu 2.2uF. Możliwe, że przez pojemność układ UCL1 pracuje niestabilnie ?
Jakim cudem 10 krotnie powiększyła mu się pojemność?
Zmierz po wylutowaniu.
#11 Re: Samsung np350v QCLA4 LA-8861P - brak napięcia na Vcc kości bios
by matic • 14 August 2024, 07:52
Yamaiko wrote:Zmierzyłem ten kondensator i ma 25uF a powinien mieć według schematu 2.2uF.The capacitor connected to pin 14 of chip UCL1 is CCL7. Its value according to the schematic is 22µF (not 2.2µF).
Yamaiko wrote:Możliwe, że przez pojemność układ UCL1 pracuje niestabilnie ?Yes, the designer of this board slightly exaggerated the value of these capacitors, which are at the limit of the chip's performance.
For the permanent fix, replace the chip UCL1 and also replace both larger capacitors next to it with their half value:
C16 -> 4.7µF/6.3V, package 0603
CCL7 -> 10µF/6.3V, package 0805
Re: Samsung np350v QCLA4 LA-8861P - brak napięcia na Vcc kości bios
by Google Adsense [BOT] • 14 August 2024, 07:52
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