HP shadow Genie 4 tpn-q211 notebook cannot be powered on for repair after falling

Machine model: Shadow spirit 4 tpn-q211

Board No: dag3ddmb8c0

Fault phenomenon:Won’t Turn On after laptop falling

Maintenance process:

HP shadow wizard 4 laptop fell Won’t Turn On, preliminary test button boot no response, really no booting.Add adapter, measurement found no common point VCC, check charging chip bq24780 working conditions, found that its 6 pin VCC is only 1.4V, obviously wrong, remove the series voltage divider circuit resistance of 6 pin, replace two good, power on test, common point has 19v, but no power on.

The power identification signal of the main board adapter power interface is only 0.4V, which should be the wrong value of VCC. Install the battery to test and charge it normally. After half an hour of charging, the battery can meet the power required by the main board switch.

When the battery is installed, there is only 5.0V standby VCC on the whole board. When you press the power on button, a 3.3V standby VCC comes out. But just for a moment, look at the 3.3V VCC chip, silk screen L8 model rt6258b, check the chip manual, and add the 3.2V reference VCC output from 11 pin lod3 to its 6 pin as EN. At this time, there is a stable 3.3V standby VCC output,The 3.3V VCC chip is good.Next, check the EC.

HP shadow Genie 4 tpn-q211 notebook cannot be powered on for repair after falling Figure 1.

This board EC uses it8987, this chip is with program, look for HP shadow Wizard 2 G35 drawing as reference, EC is the same, you can refer to pin bit function, measure its standby conditions:VCC, sleep, AC recognition, EC reset are normal.Press the power on button, EC’s 107 pin receives nbswon1 ා, then EC generates reset signal rsmrst ා, power on signal dnbswon ා and EC power good signal EC_PWROK,However, the start-up signal dnbswon “generated by EC to Nanqiao will drop instantly when it comes out.

The oscillograph is used to test the waveform again. It is found that the waveforms of 2, 5 and 6 pin of BIOS appear at the moment of connecting the battery VCC, which is equivalent to that EC configures its own tube pin function definition through BIOS reading program, which means that this EC does not have a program.VCC time, the standby program of VCC v VCC v VCC v is closed automatically, but the standby program of VCC v VCC v is not closed at the same time.When the power on key EC is pressed to receive switch Switch signal, the reset signal to Nanqiao will jump from 0 to 3.2V immediately. However, the power on signal sent by EC to Nanqiao will jump from 0 to 3.2V, and then it will drop to 0V again. After a while, 3.3V and 5V will disappear at the same time, and then switch will automatically start again.Measurement of all secondary VCC is not Short circuit, each major Inductor is not Short circuit.The BIOS failure remains unchanged.

HP shadow Genie 4 tpn-q211 notebook cannot be powered on for repair after falling Figure 2.

Because of the broken machine, it is suspected that the bridge has been damaged. Go directly to BGA Rework Station to dry the bridge. As a result, the sound of the waves is still the same.When measuring the standby conditions of the 8-generation bridge, the ones measured with multimeter are all good, and the oscillograph is used to measure the waveform again.

HP shadow Genie 4 tpn-q211 notebook cannot be powered on for repair after falling Figure 3.

When the bridge VCC chip apw8713 (PCH VCC, 1.05v) is hit, it is found that VCC waveform unstable is output intermittently.Remove the apw8713 chip and replace it directly, and then test the waveform is perfect and stable. Press the power on key switch again, and the current is up, but it is still not bright.After testing VCC, it is found that there is no VCC in the video memory. Replace the up1666q chip, and then power up the test. The screen is on. Install Nand into the system and test everything is normal and the fault is removed,This is the end of the repair.

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