HP 14 DA0U33MB6E0 3/5ALW strange behavior

[ruletero]

Hi everyone

MB Model: DA0U33MB6E0

Fail: Not turn on, power led on

I have +5VPCU, +3VPCU, NBSWON1#, the 5/3 alw power supply is turn on by s5_ON after press power button but in +3VS5 only get 1.7v and in +5VS5 only get 3.5v.

Before I changed +5VS5 mosfets (PQ27 and PQ28) because these were in short, also I changed PU4, nothing changed.

I have 155 ohms in PL19 and 131 ohms in PL21 then I guess don't have a short, if I press the power button the two voltages are present but low.

What thing can I check, please help

[mcplslg123]

Re: HP 14 DA0U33MB6E0 3/5ALW strange behavior

Resistance on PL19 as well as PL21 is low. Remove both the coils and mesaure resistance on both pads of PL19/21 and see which side is having low resistance. After removing both these coils ,try tu turn on and see if you get stable 3V/5V on IC side of coil pads. You may need to inject voltage on pads showing low resistance.Btw, was the IC new and PQ27/28 of same designation??

[ruletero]

Re: HP 14 DA0U33MB6E0 3/5ALW strange behavior

PL19 removed, mosfet side 155 ohms, charge side 383 ohms.
PL21 removed, mosfet side 129 ohms, charge side 438 ohms.

I guess with coils removed I would't have voltages because FB are not connected then I can't check the voltages, the low resistence is on IC side then charge side isn't in short.

I changed again PU4 with a new IC, same behavior, PQ27 and PQ28 are from donate MB and ther were probed before.

:/

I inyected 1v in both pads of two coils:

Only charge side of PL19 shows consumes 14 mA

I inyected 3v in both pads of two coils:

PL21 charge side consumes 19 mA
PL19 charge side consumes 64 mA

[mcplslg123]

Re: HP 14 DA0U33MB6E0 3/5ALW strange behavior

I could'nt understand what do you mean by charge side and mosfet side. The two pads of coil-one pad is input side connected to 3/5V regulator and the other pad is output side.

[ruletero]

Re: HP 14 DA0U33MB6E0 3/5ALW strange behavior

mosfet side = 3/5 v regulator side
charge side = output side

Sorry for the confusion

[mcplslg123]

Re: HP 14 DA0U33MB6E0 3/5ALW strange behavior

With such a low ohms on regulator side, your IC seems bad to me. Remove the IC(DONT APPLY POWER WHILE THE IC IS REMOVED, ELSE YOU WILL KILL IT) and measure resistance on both pads of PL19/21 again.

[piernov]

Re: HP 14 DA0U33MB6E0 3/5ALW strange behavior

These are resistance to ground measurements, not diode mode to ground right?

[ruletero]

Re: HP 14 DA0U33MB6E0 3/5ALW strange behavior

With such a low ohms on regulator side, your IC seems bad to me. Remove the IC(DONT APPLY POWER WHILE THE IC IS REMOVED, ELSE YOU WILL KILL IT) and measure resistance on both pads of PL19/21 again.

But I changed IC two times, one new and one working from donate MB. That is the "strange behavior" for me, with both IC the voltages were the same. now I'm suspecting from the low mosfet.

Let me do that please.

[ruletero]

Re: HP 14 DA0U33MB6E0 3/5ALW strange behavior

These are resistance to ground measurements, not diode mode to ground right?

Amm I put multimeter red cable to ground and black cable to coil/ pad/ ic in a diode mode.

[ruletero]

Re: HP 14 DA0U33MB6E0 3/5ALW strange behavior

With such a low ohms on regulator side, your IC seems bad to me. Remove the IC(DONT APPLY POWER WHILE THE IC IS REMOVED, ELSE YOU WILL KILL IT) and measure resistance on both pads of PL19/21 again.

IC Removed..

PL21 mosfet side 139
PL21 output side 430


PL19 mosfet side 155
PL21 output side 441

The mosfets are bad??

[Stevedb]

Re: HP 14 DA0U33MB6E0 3/5ALW strange behavior

Hello

You can better use resistance mode scale 200 ohm.

Regards

Steve

[ruletero]

Re: HP 14 DA0U33MB6E0 3/5ALW strange behavior

Thank you Steve. My multimeter has diode mode and resistence 200 ohms mode together.

I replaced IC again with a working IC. Also I replaced 3/5 alw 's mosfets again with a working mosfets.... Same result

[Stevedb]

Re: HP 14 DA0U33MB6E0 3/5ALW strange behavior

Can you sent a picture. Because normal you must use function test then to set only on resistance mode. Because on diode mode depends on multimeter can put till 8v to diode mode on the board. It is better to use just resistance mode.

Best regards

Steve

[stingerchamp]

Re: HP 14 DA0U33MB6E0 3/5ALW strange behavior

Normally when 3v ,5v ldo drops it is directed towards e or KBC as 3vpcu or ldo is vcc for EC
So you have to change KBC as well

But in your case

Ldo is fine and output is dropping

Two reasons

Ec_on or s5_on signal has a glitch or at output after coil there is a capacitor leakage or missing or bad

You change ic but do not change capacitor at the output Line , line is same,
Check feedback pin value and bred if available

[ruletero]

Re: HP 14 DA0U33MB6E0 3/5ALW strange behavior

Normally when 3v ,5v ldo drops it is directed towards e or KBC as 3vpcu or ldo is vcc for EC
So you have to change KBC as well

But in your case

Ldo is fine and output is dropping

Two reasons

Ec_on or s5_on signal has a glitch or at output after coil there is a capacitor leakage or missing or bad

You change ic but do not change capacitor at the output Line , line is same,
Check feedback pin value and bred if available

Ok, let me do it. Thank you for your help and your time, really.

[ruletero]

Re: HP 14 DA0U33MB6E0 3/5ALW strange behavior

Thank you everyone, I had to return the laptop to the client before check again it, for now this thread is closed. Thank you!