2015年10月28日星期三

HP 500 Laptop EC Control Circuit Diagram And Failure Analysis

1, U20 (KB910) EC control chip, if Pseudo Soldering, there is no response when press the power button; if KB930 damaged, will often appear system halted, or no response when boot, or the keyboard will not be able to use.
2, C362, C363 resonant capacitance, if damaged, will system halted when system boot. If resonant capacitance electric leakage, the clock will not be accurate.
3, Y1 crystal oscillator, if damaged, there is no response when press....read more

2015年10月24日星期六

HP 500 Laptop Power Supply For Memory Diagram And Failure Analysis

1, PU5 (ISL6269 power control chip for memory), if damaged, the led will light when press power button, but can not boot, or does not display, diagnostic card code C1, or blue screen, or often auto reboot, or black screen with alarm.
2, PQ16 mosfet, if damaged, will auto reboot when boot, or blue screen and system halted.
3, PQ17 mosfet, if damaged, will system halted or reboot, or auto power off from protection circuit.
4, PC42 Filter capacitor, if damaged, will system halted or reboot, or can not boot....read more

2015年10月22日星期四

HP 500 Laptop Power Supply For CPU Diagram And Failure Analysis

1, PU9 (MAX1532) Power control IC, if damaged, will auto shut down, or system halted, or can not boot, or led lights but can not start up. If it pseudo soldering, will be often reboot or auto shut down.
2, PQ21, PQ25 mosfet, if they damaged, will auto shut down after boot, or the fan spin for an instant and shut down. If one mosfet damaged, will auto shut down when run a big program.
3, PQ22, PQ26 mosfet, if damaged, the led will flicker one time when press the power button, then shut down. Or auto shut down after boot.
4, PC85, PC115 Filter capacitor, if short circuit, will not able to charge, and can not boot, too.
5, PC94, PC95, PC285, PC286 Filter capacitor, if damaged, will not be able to boot or system halted.
6, PL12, PL13 inductor, if pseudo soldering, will generate cheep noise when boot.
7, PR104 resistor, if pseudo soldering, will not able to boot....read more

2015年10月18日星期日

HP 500 Laptop System Power Supply Diagram And Failure Analysis

1, The power control chip MAX8734 damaged, will not be able to boot, there is no response when press the power button.
2, PQ11 mosfet damaged, will auto shut down after boot, or auto power off after work for a period of time, or the led flickers and can not start up.
3, PQ12 mosfet damaged, will not response when press the power button, or the led lights one time, then put out immediately.
4, PL4 filter inductance pseudo soldering, will require starting up many times, just can boot successfully.... read more

2015年10月14日星期三

ACER V5-471G laptop does not boot share

An acer V5-471G notebook can not start up, connect the dc power supply, the standby current 0.006A, press the power button, the current up to 0.02A, Keep 2 seconds, then return to 0.006A, the power led does not light. Open the laptop, check the operating conditions for RT8223, VIN 19V, test 3.3V_AUX_S5, 5V_AUX_S5, both ok, 3.3V_PWR and 5V_PWR have not voltage. So check timing sequence.

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Several signal must come out before 3V\5V comes, test +3.3V_RTC_LDO it is  3.3V, +RTC_VCC it is 3.3V, +PWR_SRC it is 19V, they are normal. Test S5_ENABLE, the voltage is 0V. .... read more

2015年10月11日星期日

Lenovo Y470 does not display share

A Lenovo Y470 laptop, it can start, but doesn’t display. The version : LA-6881P. Connect power supply, the standby current 0.018A, press the power button to start up, the current is 0.088A, it does not display.
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Open the notebook, start up, test +5VALW +3VALW, all are ok. Then test PL501 +1.5VP, OK. But test +5VS, +3VS, they are 0V voltage, So check the 4-pin of U46, the voltage is 0V, too. Then check the G pole of Q99, the SUSP is 0V, It is normal. So check the D pole, the +VSB is 0V, it is not normal.... read more
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2015年10月5日星期一

Lenovo Y450 laptop automatic shutdown share

A Lenovo Y450 laptop, remove the battery, connect the adjustable DC power supply, the standby current is 0.059A, the value is higher than normal one, Push the power button and the current up to 0.53A, then automatic shutdown. Open the notebook, checked each inductance, find the resistance is only about 130 ohm between PL6 5VPCU and GND. The normal value should be more than 300 ohm.

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There is a little short circuit, but the laptop can trigger, so solve automatic shutdown problem first. According to the previous maintenance experience, usually it is 1.8V circuit problem, this voltage is for the graphics card. So, connect power supply again to test, the 1.8V is normal when automatic shutdown. ....read more

2015年10月2日星期五

Lenovo Y470 notebook one common fault share

A Lenovo Y470 notebook, can not start up when connect power or using battery, The led of power adapter is flashing when connect power. Open the laptop, test the power input terminal with multimeter, there is not short circuit, then test B+ point, find short circuit, then test the mosfet PQ302, PQ302 was damaged, remove it and replace a new one. ... read more