HP TPN-C133notebookNon-startup maintenance

HP TPN-C133notebookNon-startup maintenance

“Machine model” HP TPN-C133

【 Fault phenomenon 】 There is standby current, which does not trigger.

[Maintenance process] After receiving a machine that is not triggered by HP Light and Shadow Wizard TPN-C133, first remove the motherboard and roughly check all the inductors on the motherboard to see if there is a short circuit, so as not to cause other problems. After the resistance test, it is found that there is no inductance with abnormal resistance, and it is ready for power-on test.

Plug in the regulated power supply, and the standby current is 0.006a This standby current is normal for the game to start. Press the power-on key and find that the motherboard is not working. Use a multimeter to test the standby condition of the motherboard.

Maintenance of HP TPN-C133 notebook unable to boot Figure 1

It is found that the standby voltage of 3V and 5V is normal, but the bridge power supply of 1.05V is not.

HP TPN-C133 Notebook Maintenance without Booting Figure 2

Open the corresponding motherboard board in Xinzhizhao maintenance software.blueprint, found a 1.05V power supply chip, and found that his EN was generated by 1.8V PG, and 1.8V EN was generated by PCH_PWR_EN signal of EC chip. Found that none of these three were turned on, started to check the working conditions of EC chip.

Maintenance of HP TPN-C133 notebook when it is not turned on Figure 3

Notebook HP TPN-C133 Notebook Maintenance without Booting Figure 4

The working conditions of the measured EC chip have been met. Try brushing a BIOS first. After brushing the BIOS, the fault is still found. Because this signal has a certain relationship with the bridge, we decided to inquire about the working conditions of the bridge.

In the test, it was found that the 32.768MHz clock of the bridge had no waveform, so we found a material board and removed a crystal oscillator to try it. As a result, the crystal oscillator still didn’t vibrate. Here we suspected that it was caused by the bridge that didn’t trigger, and we just had a bridge that could trigger but would lose power. After obtaining the customer’s consent, we tried it on the bridge, and the crystal oscillator waveform was immediately available, and the current could go up to more than 300. Sure enough, it was the bridge that caused the non-triggering.

HP TPN-C133 Notebook Maintenance without Booting Figure 5

[Maintenance result] I ordered a certain bridge on the Internet and came back. After replacement, the single board tested normal current. I installed the main board in the machine to start the test, and it can be started normally. The system test is very stable, and other functions are normal, so the maintenance is over.