They brought a laptop to our service HP Pavilion 15. n055sr with a diagnosis "dead" or "does not turn on". Indeed, when connecting it to the network (with or without battery), the laptop did not react to the power button. The decision was very unexpected (and suitable not only for HP laptops, but also for other brands), but first things first.
The client claimed that he handled the laptop carefully, didn’t flood it, didn’t hit it and, in general, it turned off normally after work and didn’t turn on again.
As usual, we carried out standard diagnostics and visual inspection of the motherboard for flooding and mechanical damage. The cooling system was also normal and clean enough. On the laptop overheating obviously it doesn’t seem like we thought, and decided that perhaps the reason for everything was a failure of the BIOS firmware (BIOS).
BIOS firmware reset on a laptop HP Pavilion G6 15.n055sr you can only do it by disassembling it completely, unlike, for example, the case with resetting the BIOS on a Packard Bell laptop, where everything is much simpler (the link can be found on how the BIOS is reset on Packard Bell laptops). After disassembling the laptop, we remove the BIOS battery from the motherboard for 10-15 minutes, and without wasting time we go to drink coffee. )
After 10-15 minutes, insert the battery back, throw the cable from the laptop’s charging connector to the board and see this picture, the charging indicator that did not light up initially lights up:
Next, press the power button and, lo and behold! , the laptop turned on, although disassembled, but it worked fine. The thing is done, we thought, and assembled the laptop completely. connected the charger and the HP Pavilion 15 laptop does not turn on again. AND power indicator also does not burn! In general, everything is as before.
The decision came by itself. we began to disassemble the laptop, removed the keyboard, disconnected the remaining cables and "for good luck" connected the power, and the power indicator again glowed with a magic light.
Further, everything turned out to be very simple, by the method of sequentially connecting all the cables and devices (Wi-Fi adapter, memory, hard drive), it was revealed that the laptop does not turn on with the keyboard connected.
To determine what the reason is: in the keyboard controller on the motherboard or in the keyboard itself, it is easiest to connect a known-good keyboard of exactly the same model (look at the part number on the back of the keyboard, we had the number on the keyboard like this: 719853-251 ) and check the laptop, but not everyone has a spare laptop keyboard on hand! And we didn’t have it. Therefore, we use another universal way to test the keyboard.
1. Disconnect the keyboard from the laptop:
2. We take a multimeter and transfer it to the resistance measurement mode in the megaohm range (MΩ):
3. Then we alternately check the resistance between the contacts of the keyboard loop. First, between the first and second contact, then between the first and third, between 1m and 4m, 1m and 5m, and so on until the last contact. Then we put one probe of the multimeter on the second contact of the loop, and the second probe on the third contact of the loop and also check the short circuit between 2m and all other contacts of the loop. We carry out such a procedure with all contacts.
As a result, we got resistance around 30k ohm between 3 and 4, 3 and 5, 3 and 6 (and in several more cases), which clearly indicates keyboard malfunctions. It was either flooded or has some kind of internal hidden defects. The Keyboard health check method applicable to keyboards of almost any laptop manufacturer (LENOVO, ACER, SAMSUNG, TOSHIBA, etc.)
After keyboard replacement a laptop HP Pavilion G6 15.n055sr started to turn on and work normally. After several hours of testing in different modes, we ascertained the serviceability of the laptop with a new keyboard.
It is worth noting that diagnostics and testing to identify laptop malfunctions in the case when the laptop does not turn on / not start, you need to start with the sequential shutdown of all devices and modules connected to it. If this article was useful to someone, please write your comments below. Your opinion is very important to us.
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