Hp 450 dead

[mcplslg123]

MODEL:HP PAVILLION 450
PCB:INVENTEC HARVEY 6050A2493101

PROBLEM: TOTAL DEAD, NO DC JACK LIGHT.

Here is what i've found out.

01.Q6010-Source 19V,gate-24V,Drain 19V
02.charging IC BQ24728 measurements:
ACN/ACP-19V
cmsrc-19V
ACDRV-24V
ACPRES-2.9V(??)
ACDET-2.62V
SDA/SCL-3V
REGN-6V

R6024 has 3V Pull up ok on one side but on ther side connected to Charging ic's ACOK pin is 2.9V . The resistor is measured out of circuit 10K.

ADP_ID is ok at 0.58V measured on D6015. Other end of diode is stable 3V.

KBC pin 70-0.58V. I've measured PIN 71/72/73/35 and they are all ok as per schematics.

3V/5V LDO present.

Offline Consumption is 0.012 Amps at the beginning and then jumps to 0.023A but nothing is warming up though a slight increase in temperature can be filled near TPS 51123 IC. Resistance on 3/5V coil is correct as per working m/b.

All the fets like Q6011/Q6012/Q6000/Q6001/Q6100/Q6101/Q6150/Q6151 are ok .

Parts replaced:
01.BQ24728-NEW
02.IT8517-NEW
03.TPS 51123-NEW
04.Both eprom flashed with known good bios.

What can be wrong here?? Any ideas??

Status-all the same-dead with no dc jack light.

[Techtiger]

Re: Hp 450 dead

is the RTC_RTCRST# section ok ? try with a another DC jack , Q103 R14 voltage is ok ?

[SMDFlea]

Re: Hp 450 dead

Did you replace the ITE with the same part number HXA/HXS .Check voltage on R802 pin 1

[piernov]

Re: Hp 450 dead

EN_3V_5V present or missing?
Check resistance to ground on 3V/5V LDO as well.
Also check voltage on EC pin 14 and make sure 3.3V makes its way to VSTBY pins.

[mcplslg123]

Re: Hp 450 dead

is the RTC_RTCRST# section ok ? try with a another DC jack , Q103 R14 voltage is ok ?

RTC section is ok. Q103/R14 voltage is not ok and i've already observed. R14 is 5V on one side and 0V on ac led side. Dc jack i've replaced.

[mcplslg123]

Re: Hp 450 dead

Did you replace the ITE with the same part number HXA/HXS .Check voltage on R802 pin 1

ITE replacement with same part number for sure. R802 is not populated on mb though on pads i've 3.3v on one side and 0V on the other side(which is connected to R769)

[mcplslg123]

Re: Hp 450 dead

EN_3V_5V present or missing?
Check resistance to ground on 3V/5V LDO as well.
Also check voltage on EC pin 14 and make sure 3.3V makes its way to VSTBY pins.

EN_3V_5V present. Resistance on LDO line is ok compared to working mb. EC pin14 is 2.94V. VSTBY pins(L516) have 3.3V.

[piernov]

Re: Hp 450 dead

If EN_3V_5V is high then U6100 should produce VRP5V0A and VRP3V3A.

[mcplslg123]

Re: Hp 450 dead

If EN_3V_5V is high then U6100 should produce VRP5V0A and VRP3V3A.

In this platform, VRP5VOA & VRP3V3A comes after turning on only. EN_3V_5V is definitely high and stable.

[piernov]

Re: Hp 450 dead

EN_3V_5V is ENC signal for TPS51123.
According to datasheet, ENC: "Channel 1 and Channel 2 enable input. Pull up to the voltage ranging 3.3-V to 5-V to turn on both switcher channels. Short to ground to shutdown them."
According to Table 3 of datasheet, all the voltage regulator outputs are turned on when EN0 isn't tied to ground and ENC is high. EN0 is ok since you at least get LDO outputs (if EN0 was tied to ground it would disable LDO). ENC is high. Therefore the buck output should be present.

Additionally, according to schematics, AC_LED# power comes from P5V0A through R14

[mcplslg123]

Re: Hp 450 dead

I agree with you theoritically as with the conditions mentioned, there should be output on coils. But exactly that's not the case on this platform. I've a working mb of same platform and there is no voltage on 3v/5v coil though ac led on dc jack glows. The voltage on coils appear only after turn on. Schematic doesnt mention it as suspend voltage also adding to more confusion. I've checked voltage/resistance on each and evry pin of TPS51123/BQ728 and there is no difference on any of the pins except BQ728 ACOK pin which is at 2.9V and the other side of pullup resistor is stable 3.3V.

If there is no more ideas , then i think i need to give up on this case as i'm still not able to understand the root cause of the problem. Customer is not in hurry though.

[piernov]

Re: Hp 450 dead

Maybe the schematic is wrong and something is pulling TRIP1/TRIP2 of the TPS51123 to ground. And maybe the LED is powered by the 5V LDO instead.

So ADP_PRES is 3.3 on the other board? And it was 2.9V as well before replacing EC and charger IC on this board?

[SMDFlea]

Re: Hp 450 dead

Can you check Pin 18 ENC EN_3V_5V on both boards ,and R6997,R6998 if present. On page 4 of the tps datasheet theres a chart with the VO and VIN standby current in mA and μA ,what does pin 18 have on both boards before and after pressing the power button.