hp spectre x360 dead - please help

[bylos]

Re: hp spectre x360 dead - please help

Short update : I have taken all BQ24715 pin voltages with or without AC power.
The laptop is always off during these measurements :

PIN	LABEL	w/o AC	w/ AC
1	ACN	10,91	19,64
2	ACP	10,91	19,64
3	CMSRC	0,042	18,36
4	ACDRV	0,039	20,46
5	ACOK	0	3,332
6	ACDET	0	2,847
7	IOUT	0	0
8	SDA	3,12	3,12
9	SCL	3,12	3,12
10	CELL	0	3,73
11	nBATDRV	4,592	4,059
12	SRN	11,29	11,29
13	SRP	11,29	11,29
15	GND	0	0
15	LODRV	0	0
16	REGN	0	6,024
17	BTST	11,04	11,04
18	HIDRV	11,29	11,29
19	PHASE	11,29	11,29
20	VCC	0	19,47

So BQ24715 seems to working, still the battery is not charging when AC power is plugged... How can I check that PHASE / HIDRV / LODRV are properly working ?

[mon2]

Re: hp spectre x360 dead - please help

Gorgeous chart !! Nice to read.

Remove the battery. Power up with only the adapter.

Does the logic board work properly ?

When you have the adapter & battery attached -> logic board works ?

What does the Windows OS report for the battery status ? Does it show charging ?

Of immediate concern is:

4 ACDRV 0,039 20,46

The GATE voltage should be about +6v higher than the adapter voltage to turn on the mosfet(s).

Post the markings on the mosfets that are interfacing to your external DC adapter so we can hunt the datasheets.

The charger IC may be defective but will know more after some measurements.

Have you checked if the mosfets are defective on this logic board with resistance checks ?

[bylos]

Re: hp spectre x360 dead - please help

Hi !
First I would like to apologize for the loooong delay because I could not find any free time to investigate further
Also thank you very much for your answer !

I have completed the table with measurements without battery (only AC power cord plugged) :

PIN	LABEL	w/o AC	w/ AC	no BAT
1	ACN	10,91	19,64	19,65
2	ACP	10,91	19,64	19,65
3	CMSRC	0,042	18,36	18,38
4	ACDRV	0,039	20,46	20,49
5	ACOK	0	3,332	3,336
6	ACDET	0	2,847	2,85
7	IOUT	0	0	0
8	SDA	3,12	3,12	0,087
9	SCL	3,12	3,12	0,087
10	CELL	0	3,73	3,735
11	nBATDRV	4,592	4,059	0,595
12	SRN	11,29	11,29	0,758
13	SRP	11,29	11,29	0,758
15	GND	0	0	0
15	LODRV	0	0	0
16	REGN	0	6,024	6,031
17	BTST	11,04	11,04	5,849
18	HIDRV	11,29	11,29	5,849
19	PHASE	11,29	11,29	0,758
20	VCC	0	19,47	19,5

So the voltage looks rather similar than the ones posted by justin35 in this thread when power is plugged but battery is not

The windows OS indeed shows that the battery is charging ! So it seems that AC power is detected, but the battery is actually not charging (level stays constant and decreases if I use the laptop)

All the MOSFETS seems fine (no gate shorted) except for PQ8: Gate is not shorted, but source and drain are ! (only 1.3 Ohm using portable multimeter)
Do you think this could be the source of laptop working but not charging ?

If I quote the "Laptop battery charging circuit" thread :

The other MOSFET could also be shorted, in the case of an HPB topology the main power rail will be present since current will flow through the shorted MOSFET and through the body diode of the other MOSFET, but some signal from the charger IC might be missing causing the platform not to turn on.

Best regards,

[mon2]

Re: hp spectre x360 dead - please help

Yes, a defective mosfet can cause problems.

Replace mosfet PQ1 and test again. AliExpress will have these or if in a rush, a valid replacement will work from your local market.

[bylos]

Re: hp spectre x360 dead - please help

Dear mon2, dear all,

I received PQ1 and PQ8 from aliexpress and changed them
I think the voltages around BQ24715 are now much as expected, however the battery is still not charging
What is the most important is that now, ACDRV pin (PQ1 and PQ8 gates) shows 25.90 V which is what expected.
Also HIDRV is now 15.80 when battery and AC are connected.
Finally, on PQ1's drain, I measure the battery voltage instead of AC input voltage. Shouldn't PQ1 and PQ8 be both active when their gate is at 25.90 V ?

Here is a summary of the voltages with either battery only, AC power only, or both together, before and after replacing PQ1 and PQ8 :

			BEFORE PQ1 / PQ8 REPLACEMENT	AFTER PQ1/PQ8 REPLACEMENT		
PIN	LABEL		AC	BAT	AC+BAT		AC	BAT	AC + BAT
1	ACN		19,65	10,91	19,64		0.88	10.81	11.19
2	ACP		19,65	10,91	19,64		0.88	10.81	11.19
3	CMSRC		18,38	0,042	18,36		20.07	0.0	20.07
4	ACDRV		20,49	0,039	20,46		25.90	0.0	25.90
5	ACOK		3,336	0	3,332		3.337	0.0	3.337
6	ACDET		2,85	0	2,847		2.847	0.0	2.847
7	IOUT		0	0	0		0.0	0.0	0.0
8	SDA		0,087	3,12	3,12		0.1	3.128	3.130
9	SCL		0,087	3,12	3,12		0.1	3.128	3.130
10	CELL		3,735	0	3,73		3.733	0.0	3.733
11	nBATDRV		0,595	4,592	4,059		0.725	4.484	4.232
12	SRN		0,758	11,29	11,29		0.878	11.18	11.18
13	SRP		0,758	11,29	11,29		0.878	11.18	11.18
14	GND		0	0	0		0.0	0.0	0.0
15	LODRV		0	0	0		0.0	0.0	0.0
16	REGN		6,031	0	6,024		6.032	0.0	6.031
17	BTST		5,849	11,04	11,04		5.823	10.93	15.80
18	HIDRV		0,758	11,29	11,29		5.823	11.18	15.80
19	PHASE		0,758	11,29	11,29		0.878	11.18	11.18
20	VCC		19,5	0	19,47		19.47	0.0	19.47

If you could please confirm that when PQ1 and PQ8 gates are at 25.90, both should be active ? So I should read something like 20 V on PQ1's source and drain ?

Best regards (and have good summer's holidays if you have the chance !)

[bylos]

Re: hp spectre x360 dead - please help

Oh it seems that transistors from Aliexpress are quite unreliable.
The one I mounted on the board has no diode behaviour between source and drain. I tested others, some have short circuits, some have 0.5 V threshold.
Could you please advise on what should be a consistent diode behaviour for this kind of NMOS transistor (https://datasheetspdf.com/pdf-file/9...OS/EMB20N03V/1) between :
- Source to drain
- Gate to drain

Best regards !

EDIT : I replaced PQ1 with another one which has a diode behaviour (thres. 0.5 V) between source and drain : BATTERY IS CHARGING

Still I am wondering if the one I put in place is properly working as there is a 0.5V dropdown as if the transistor was not active, and the current flows through the forward diode...

[mon2]

Re: hp spectre x360 dead - please help

Hmm. The readings from 1 & 2 AFTER the replacement do not look correct.

After you have replaced the mosfets, you no longer have voltage on ACN & ACP ? Can you confirm your soldering ? Will review more after reaching the office.

In the meantime, remove all power -> check the resistance of the new mosfets for the DCIN side. Each resistance check should be of a high resistance value.

Which mosfets were purchased ? You can also check them while they are off the logic board.

Do you have spares ? Such mosfets are quite common and you may be able to locate them in your local markets as well.

[bylos]

Re: hp spectre x360 dead - please help

Hi mon2, thank you for your reply !
=> this is the MOSFET I purchased : https://datasheetspdf.com/pdf-file/9...OS/EMB20N03V/1
I just edited my previous post to say that it is now working
Again, transistors purchased from Aliexpress have to be double-checked.
Still I am not sure that the one I put in place is correct, but at least this is working.

Thank you very much for being active on this forum and providing such support !

EDIT : pin 1 & 2 are now 19.14 and 19.16 V respectively while battery is charging !