HP G62-460SS no power

Hello, I have received this HP G62-460SS laptop with DAAX1JMB8C0 motherboard, with PD19 burned and without any response.
After replacing PD19 and having 19V on Vin it still doesn't turn on. +5V_ALWP and +3V_ALWP are not present. On PU4 (RT8206B) I only have voltage on Pin 4...13.9V and Pin 6...19.5V
The rest of the pins are at 0V except for pin 12 and 15 that have only 0.02V

I have substituted PU4 but the values are the same.



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Hola, me ha llegado este protatil HP G62-460SS con placa base DAAX1JMB8C0, con PD19 quemado y sin respuesta alguna.
Tras sustituir, PD19 y tener 19V en Vin sigue sin encender. +5V_ALWP y +3V_ALWP no estan presentes. En PU4 (RT8206B) olo tengo voltaje en Pin 4 ... 13,9V y Pin 6 ... 19,5V
El resto de pines estan a 0V execpto pin 12 y 15 que tienen a penas 0,02V

He sustituido PU4 pero los valores son los mismos.

Hello!

- Measure the resistances to ground on coils PL5, PL9.
- Measure the resistances to ground on pins 1, 3, 5, 7 of chip PU4.

Pin 1 on PU4 is shorted to ground. I have unsoldered PC86 but the short continues, and PC86 is OK.
I have desoldered PU4 again and there is no short on Pin 1 of the motherboard, but I have measured on the chip and there is no short either. In the original Chip there is also no short with the unsoldered chip.
Pin 3, 5, 7, PL5 and PL9 its ok
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Pin 1 en PU4 esta en corto con respecto a masa. He desoldado PC86 pero el corto continua, y PC86 esta OK.
He vuelto a desoldar PU4 y no hay corto en Pin 1 de la placa base, pero he medido en el chip y tampoco hay corto. En el Chip original tampoco hay corto con el chip desoldado.
Pin 3, 5, 7, PL5 y PL9 con respecto a masa esta ok

Solder the old (original) chip PU4 back to the board and remeasure the resistance to ground on pin 1 of this chip before connecting the power supply to the board.

Following your instructions, I have soldered the old chip. Before turning on I checked that pin 1 was not shorted. I have fed and now all the voltages appear and the equipment turns on.
Is it possible that applying heat to solder and desolder has internally restored the chip?
Would it be advisable to change it?

P.D. After turning it on and off, and leaving it idle for a while, it is back to the beginning, only voltage on pin 4 and 6 of PU4.
Unlike before, in pin 1 there is no short and in PL5 and PL9 I have a low resistance, all this taking as reference the positive tip in ground and negative in coils.
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Siguiendo tus indicaciones, he soldado el viejo chip. Antes de encender he comprobado que el pin 1 no estaba en corto. He alimentado y ahora aparecen todos lo voltajes y el equipo enciende.
Es posible que al aplicar el calor para soldar y desoldar se haya reestaurado internamente el chip?
Sería recomendable cambiarlo?

P.D. Después de encender y apagar, y de dejar un rato en reposo, vuelve a estar como al principio, solamente voltaje en pin 4 y 6 de PU4.
A diferencia con antes, en el pin 1 no hay corto y en PL5 y PL9 tengo una resistencia baja, todo esto tomando como referencia la punta positivo en masa y negativo en bobinas.

Zemog napisal/-a:Is it possible that applying heat to solder and desolder has internally restored the chip?

That's possible, but it's even more likely that the problem is with the PCB board itself. It's possible that sometimes there is a short circuit between two copper paths inside the PCB, or the some copper path loses its connection.

Zemog napisal/-a:Would it be advisable to change it?

Yes, replace this chip again to rule out a possible problem with it.

Zemog napisal/-a:Unlike before, in pin 1 there is no short and in PL5 and PL9 I have a low resistance, all this taking as reference the positive tip in ground and negative in coils.

Have you performed the resistance measurements with the power supply and main battery disconnected from the board? I also advise you to disconnect the power supply and wait about 2 minutes before taking the resistance measurements to allow the capacitors to discharge.
Charged capacitors can significantly affect resistance measurements and cause completely wrong results.

matic napisal/-a:Have you performed the resistance measurements with the power supply and main battery disconnected from the board?

Yes

matic napisal/-a:I also advise you to disconnect the power supply and wait about 2 minutes before taking the resistance measurements to allow the capacitors to discharge.

In this case, it may not have been long enough for the capacitors to discharge.

I haven't changed anything yet, but today it turned on again without problems, without me making any changes since yesterday.
I'm going to change PU4 for a new one and see what happens

As a reference, when the equipment turns on well, if I turn it off, remove the power and put it back on, the equipment no longer turns on


PD:.... When the equipment turns on it stays running all the time without problems. When I turn it off from the power button, I remove the current and reconnect it, it is when it no longer turns on anymore, until it remains disconnected from the power supply for a while.
At all times it is being tested only with the motherboard outside the equipment and without battery, directly to power (The client does not have a battery)
When it does happen, I have tried different sources, including an original HP feeder, but the result is the same.
I attach the current PU4 measurements when the failure occurs:
Pin 1: 1,9V

Pin 2: 4,9V

Pin 4: 13,9V

Pin 6: 19,4V

Pin 7: 4,9V

Pin 12: 1,4V

Pin 14: 4,8V

Pin 17: 4,5V

Pin 19/20/23/24: 4,9V

Pin 27: 4,8V

Pin 31: 0,09V

Pin 32: 4,9V

Rest of pins 0V

I have exchanged PU4 for a new one, and the above problem was corrected. Power was no longer disconnected after turning power on, off, and removing power. It turned on and off with no problem.
After assembling, the team failed again and PU4 was getting very hot.
I have exchanged it for a new one. With the motherboard completely disassembled (memory only), I connect the power and heatsink fan, I connect the power. The jack led turns on and without pressing power or anything, after 60 seconds the jack led turns off. If I remove power and put it back on, the led turns on again, but this time after 5 seconds it turns off

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He cambio PU4 por otro nuevo, y el problema anterior se corrigió. Ya no se desconectaba la alimentación tras encender, apagar y retirar alimentación. Encendía y apagaba sin problemas.
Tras ensamblar, el equipo a vuelto a fallar y PU4 se ponía muy caliente.
Lo he vuelto a cambiar por otro nuevo. Con la placa base completamente desmontada (solo memoria), conecto la alimentación y ventilador disipador, conecto la alimentacion. Se enciende el led del jack y sin pulsar power ni nada, a los 60 segundo se apaga el led jack. Si quito alimentación y la vuelvo a poner, vuelve a enceder el led, pero esta vez a los 5 segundos se apaga

Does the chip PU4 currently heating or not?

Good morning! Today when I arrive and test, the jack led turns on and off randomly. It turns on for 3 seconds, turns off and turns on again for maybe 1 second. it turns off and turns on again, maybe 5 seconds. and so on. It does not follow a time pattern, but a sequence.

When I press power, it stays stable and on and the led of the jack is stable. When you press power again to turn off, it turns off and the power jack led stays steady and on. As long as the power is not removed, everything remains stable and I can turn it on and off every time.

If I remove the power, I wait about 10 min. and reconnect. Power LED lights up but after 40-60 sec. It turns off and won't turn on again. I remove the power, reconnect it, it turns on and when it feels like it the led turns off again. When the power jack led is off, the laptop does not turn on or respond.

On this occasion PU4 does not heat anything at any time

P.D: Well, it seems to have found the culprit for so much dizziness. I have replaced PC201 which is just on the opposite side of PU4 and on the +5V_ALWP line, and so far it has not turned off again

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Buenos dias! Hoy al llegar y probar, el led jack se enciende y apaga de forma aleatoria. Se enciende 3 seg., se apaga y se vuelve a encender a lo mejor 1 seg. se vuelve a apagar y se vuelve a enceder, a lo mejor 5 seg. y asi sucesivamente. No sigue un patron de tiempo, pero si de secuencia.

Cuando pulso power, se mantiene estable y encendido y el led del jack estable. Al pulsar power nuevamente para apagar, se apaga y el led jack power, se mantiene estable y encendido. Mientras no se retire la alimentacion, todo se mantiene estable y puedo encender y apagar todas las veces.

Si retiro la alimentacion, espero unos 10 min. y vuelvo a conectar. Led de power se enciende pero a los 40-60 seg. se apaga y ya no vuelve a encender. Quito la alimentacion vuelvo a conectar, se enciende y cuando le da la gana se vuelve a apagar el led. Cuando el led del jack power esta apagado, el portátil no enciende ni responde.

En esta ocasion PU4 no se calienta nada en ningún momento

Pues parece haber encontrado al culpable de tanto mareo. He sustituido PC201 que esta justo en el lado opuesto de PU4 y en la linea +5V_ALWP, y de momento no se ha vuelto a apagar

Measure the following voltages to ground:
- On coils PL5, PL9.
- On pins 1, 3, 4, 6, 7, 13, 27, 28 of chip PU4.
- On pin 1 of diode PD14.

Diode PD14 pin count:

At the moment and after the last changes the laptop is working fine, with which I can close the repair.
When I saw your message, the laptop was already assembled and I couldn't make the requested measurements. The person urgently needed to work and since after 2 days of tests there was no error, he withdrew it
Thank you very much for the help

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De momento y tras los ultimos cambios el portatil esta trabajando bien, con lo cual puedo dar por cerrada la reparación.
Cuando vi tu mensaje, el portatil ya estaba ensamblado y no pude realizar las mediciones solicitadas. A la persona le urgía para trabajar y como tras 2 dias de pruebas no dió error, lo retiró
Muchas gracias por la ayuda