Recently received a friend of the ENVY4 ultrabook, said it was not turned on, find me to help see if it can be resolved.

       I first opened the back cover of the machine, measured the main power supply, and did not have a short circuit. So I plugged in the power supply, did not stand by, and the power light did not light up. I thought that most of the 19V power supply was abnormal. Find the drawing and start checking it.

       As a result, there is voltage at the front end of the PQ102 and there is no backend. As a result, there is no voltage at the control pin. The problem should be solved here. The results of measuring the next pipe is good, this time suddenly thought, since it is 19V to lose, then I can not pull the line to see it (it used to have similar experience).

       After a short connection, I plugged in the power supply, the power light was on, and the standby was normal. I thought it would be as simple as that, and I was happy. Since the standby is normal, start it, but the problem can't be triggered. According to experience, normal standby can not be triggered, generally circuit protection, so honestly use a multimeter to check it, see if there is a short circuit, the amount of a long time, and found that + LAN_VDD_3V3 short circuit, the problem was found.

       To deal with short-circuit or old methods, burning machine, and finally determined that the C317 is broken, directly removed not short, power on, er, trigger light machine. Quickly assembled and tested, normal. So I was going to fix a machine because I had a battery, so I pulled the power directly. Yeah, how can I directly lose power? Isn't it a little battery? Once again connected to the power supply, into the system to see, 0%, it really is no electricity, or wait for him to charge it. More than 10 minutes after watching the charge, the result is still 0%, how is it, is not shown in the charge it? Why not charge in, is the battery is broken? Should not it, Emmanuel flash, is the reason I shorted ? But this is the 19V front-end voltage, does not affect, ah, the charging IC is broken, no way, only the machine was dismantled again.

       Because the battery does not have any electricity, it is not easy to try, so use the adjustable voltage down to the battery voltage, directly connected to the charge for a while, sure enough battery is good, fill in, pull the power only with the battery Boot, everything is normal, I think it should still 19V power supply side of the problem, shut down, and found that after the shutdown power lamp is still lit orange. It seems that the short circuit does not work. Only the PQ102's control voltage can be corrected.

       So began to check the working conditions PU101, in order to PQ102 conduction, because the isolation protection tube G-level voltage must be higher than the conduction voltage 5V to fully turn on, ACDRV must have an output voltage of 24V, check the working principle of this chip The original ACDRV is the chip's internal output, then check his working conditions are satisfied. 20 feet 19V, 6 feet 16V. 16 feet 6V (when 20 feet get the main power supply, 6 feet get the adapter detection voltage, 16 feet should output the linear voltage of 6.0V).

       Then 4 feet to the output 24V to open the isolation protection tube, since the voltage is there, why is there is no 24V output, is the chip itself a problem? So find a chip to change, depressed, or no output. So call, suddenly thought, would not be this 6-pin ACDET voltage is wrong, it should not be this value, this connection is so 2 resistors and one capacitor, is the problem on this top? Because the board is small, the resistors and capacitors have no labels at all, and it is troublesome to find them. Finally they are finally found on the back of the motherboard. A certain amount, sure enough, the PR126 is too big, all of them are more than 600 K. Finally, the problem is found. A 40K resistor replaced, haha, 4 feet 24V out, into the system, can charge.

       At this point, the plane was finally repaired and it was able to make a difference.