XPS 15 7590

[bosscharles]

Hi mon2, I've got an XPS 15 7590 bit newer than this one but the charging circuitry is the same as the 9570. 20v 0a on USBC no power. Runs from a charged battery but will not run from DC charger or USB-c. PD1900 cathode reads: 20V, anode reads 20V. No voltage drop... PD1902 cathode reads 20V anode reads .002V could this be the issue? Resistor measurements all seem OK. PU1900 looks OK. 3v battery reading 2.5v...No liquid damage anywhere, previous owner mentioned it stopped working after a keyboard/topcase swap. Any insights/suggestions welcome. Thanks!

[anhbanxoi]

Hi mon2, I've got an XPS 15 7590 bit newer than this one but the charging circuitry is the same as the 9570. 20v 0a on USBC no power. Runs from a charged battery but will not run from DC charger or USB-c. PD1900 cathode reads: 20V, anode reads 20V. No voltage drop... PD1902 cathode reads 20V anode reads .002V could this be the issue? Resistor measurements all seem OK. PU1900 looks OK. 3v battery reading 2.5v...No liquid damage anywhere, previous owner mentioned it stopped working after a keyboard/topcase swap. Any insights/suggestions welcome. Thanks!

Check the mosfet near ISL charging IC and mosfet near battery connector.

[anhbanxoi]

These photos are from Precision 5530 but it may look the same in your motherboard. Check PQ1900 and PQ1902

[bosscharles]

Thanks, they visually look OK, no holes or scorch marks. How can I test them?

[bosscharles]

Also, nothing seems to get warm/hot as there is no amperage running through the system

[mon2]

What is the voltage to ground of ACOK (pin # 24) on the charger IC @ PU1900? Measure very carefully and only if your meter probes are with a fine tip. You can also consider to measure this voltage at the solder blob shown as PR1921 in the schematic.

[bosscharles]

Hi mon2, thanks for getting in touch. I do have fine tip probes, tried both pin 24 & PR1921. Reading is 0V. Does that point to PU1900 failure? Shall I replace the intersil chip.

[mon2]

Not yet. Need to check if the ISL chip is being powered. Only after it is powered, the ISL chip will monitor for a threshold voltage on the ACIN pin # 19. If this threshold voltage is met or exceeded, then ACOK will be a logic high. ACOK is an open drain pin and will only be a logic high provided that the resistor @ PR1911 is present and should be ~100k ohms AND the VDD voltage that is powering the ISL chip is present on pin # 18.

So proceed to check the following voltages to ground on:

ACIN pin #19
DCIN pin #17 ; believe you have done this earlier but confirm it again
VDD pin #18

[bosscharles]

Readings as follows:

ACIN pin #19 3.5v
DCIN pin #17 19.2V
VDD pin #18 0V

[mon2]

These are good readings. Remove all power. Meter in resistance mode. One meter probe on ACOK pin #24 on the charger IC. Other meter probe on pin #18 on the charger IC. No power again during these resistance checks.

What is the measurement? This is to confirm that the ~100k resistor is present as the weak pull-up @ PR1911.

After this, check the voltage to ground of AC_DIS @ PQ1906. If there is a high enough voltage on the gate of PQ1906, then this mosfet will enable and shunt the ACOK pin to ground.

[mon2]

Sorry, my bad. VDD is at 0 volts?? This will be an internal power rail. Can you confirm? The ISL may be defective. We can check in diode mode.

Update - in addition to checking if VDD is @ 0 volts, confirm the voltage to ground of the VDDP pin # 8.

Next, remove all power -> meter in resistance mode -> check the resistance across the resistor @ PR1908. This should be ~5 ohms (use your lowest resistance scale on your meter to measure).

[bosscharles]

Rechecked VDD is 0V, checked VDDP pin 8 which is 0V too, in Diode mode got a beep on pin8. PR1908 is open/infinite. Looks like I need to change that resistor. I'll harvest. from another board. Schematic says 4.7ohms, what voltage rating would it be?

[mon2]

Nothing special about the 4R7 resistor. Appears that this ISL is dead if VDDP is 0v.

[bosscharles]

Ordered from Aliexpress. Will report back in a week or two once it has arrived. Out of interest, what voltage readings should I be getting at VDD & VDDP? Thank you!

[bosscharles]

Hi all, Intersil chip arrived from China today. Replaced the old chip and the machine is up and running. Many thanks all!!!

[bosscharles]

Spoke too soon. The charger isn't detected properly and the battery isn't charging mon2 can you help me? What else should I look out for

[anhbanxoi]

Spoke too soon. The charger isn't detected properly and the battery isn't charging mon2 can you help me? What else should I look out for

Check PR102, change PD100

[bosscharles]

Both look fine, what do I need to look out for? what do these do? They are nowhere close to charging circuitry?

[anhbanxoi]

Both look fine, what do I need to look out for? what do these do? They are nowhere close to charging circuitry?

It's a PSID signal which determines how many wattages of the charger you have plugged in. Unable to detect the charger may come from broken PR102 (it should be 33ohm if you measure 2 ends of the resistor), PD100.
It's not close to charging circuit but it's close to charger port.

[bosscharles]

An update, so in the Bios, the charger was being detected and battery charging for a bit, and then it went to no charger detected. It must have done this about 3 times before just reporting no charger installed. Had a look at where ACIN_ISL88783 goes, PR1904, PR1906 & PC1925. This area got very very hot. Once the bios reported no charger, the area cooled off and no longer got hot… Thoughts? Can look to replace those components…. Also now wondering if I soldered the ISL properly, all the legs look fine but perhaps too much solder in the middle and grounding pins..