Acer Nitro 5 LA-H501P Not Charging, Not Powering On

[mon2]

I got 110k ohm on VDD pin #19 to GND.

No short here so the ~4 volts on VDD may be considered normal for this IC. Would have expected it to be higher as the schematic shows in the lower left corner of the charger IC page that VDD=5V. You are at 4 volts.

Review the voltage on each side of PRB12. That is, trying to confirm if the charger IC is pulling this line low intentionally OR is it that PRB12 is not mated to the same ~4 volts to park this line to a logic high '1'. If this line does not become a logic '1', the charger IC believes the adapter is not suitable. When the charger IC accepts the adapter as being suitable (by checking the adapter threshold value on the ACIN pin, then this ACOK line will be floating and that is when PRB12 performs its duty to soft park this line to a '1'.

[Growtopia Jaw]

Getting 3.936V on VDD_CHG and 49mV on AC_IN

[mon2]

This last measurement confirms that the charger ic does not like the adapter voltage so ACOK is being pulled to a logic low.

Concerned about the LDO voltage at ~4v when it should be ~5 volts.

what is the voltage to ground of pin#20 (vdd) on this ic?

confirm that the chip is soldered properly. At the start of this thread, the dcin mosfets had the boosted gate voltage so back then the adapter was deemed to be ok. Are you using the same power adapter? Do you have another adapter compatible for this machine?

if the acin voltage is high enough, only then will the asgate pin will supply the boosted voltage.

==

Measure the voltage to ground on each of the DCin mosfets @ PQB11 and PQB12. Post each measurement for the source (1-2-3); gate (4) and the drain pins (5-6-7-8).


Update:

While the full datasheet for this specific charger IC is not available to the public - no idea as to why they do this but we can perhaps learn from other Intersil charger devices that may be similar.

See attached = my bad, from this VDDP review - it is pin #20 that is the output of the LDO on these parts from Intersil. So proceed to check if VDDP is ~5 volts as it is on other devices from Intersil. Then remove all power and confirm the resistance across the resistor @ PRB21 which should be ~4.7 ohms.

[Growtopia Jaw]

I've reapplied solder on the charging IC pins and they now look fine on all four sides. I'm now getting 5.32V on both pin #19 and #20.

Yes, I'm using the same factory adapter that came with the laptop itself from the beginning of this thread. Unfortunately, I don't have any other adapter that has the same barrel plug size even though they have the same output voltage but slightly different amps. I had thought of maybe swapping the female barrel jacks but unfortunately the connector size on the motherboard is different. The other adapters are all ASUS which for the negative conductor fits into the connector but the positive conductor is bigger than the one in Acer's barrel jack.

The factory IC that came with this laptop has the chip marking "ISL88739AHRZ" while the replacement I bought has the markings "ISL88739HRZ", missing the "A". Hopefully there isn't any difference between the functionality / specs of this charging chip. I've looked up the datasheet on digikey and doing a side-by-side comparison kind of looks like there are no difference between them.

I initially changed the charging IC because when turning on the adapter, the charging IC instantly became very hot and I suspected that it might be an issue.

Factory IC:

Replacement IC:


Update:

PQB11 & PQB12:
PIN #1, #2, #3, #5, #6, #7, #8 = 19.63V
PIN #4 = 24.78V

Resistance across PRB21: 8 ohms
Double than the expected value maybe due to it having 5% tolerance?

[Growtopia Jaw]

PUB1:
pin #1 = 19.63V
pin #2 = 3.227V
pin #18 = 18.96V
pin #30 = 24.8V

[Stevedb]

Does the laptop power up now not charging is maybe push switch near melory that disable charging when you remove the back cover.

[Growtopia Jaw]

Does the laptop power up now not charging is maybe push switch near melory that disable charging when you remove the back cover.

Unfortunately no, I can just short the pins on the keyboard connector to turn on this motherboard but there is no response and the fan does not spin.

All coils are still 0V.

[mon2]

Very good progress.

Carefully measure the voltage to ground of :

pin #3
pin #4
pin #31
pin #32

post each measurement. Glad to see the voltages on ACOK and ASGATE.

update:

Next check the voltage to ground of the regulators at pu301 and pu501. Each offers a low current LDO rail. The 3v3 LDO rail is important and is used to power the KB9022 EC.

[Growtopia Jaw]

pin #3, #4 = 0V
pin #31, #32 = 19.63V

PU301:
pin #1 = No reading
pin #2, #3, #4, #5 = 19.63V
pin #6, #19, #20 = 0V
pin #9 = 0V
pin #11 = 4.5V
pin #12 = No reading
pin #13 = No reading
pin #14 = 0V
pin #17 = 0V

PU501:
pin #1 = 19.63V
pin #2, #12 = 0V
pin #4 = 0V
pin #5 = 4.5V
pin #6 = 0V
pin #7 = No reading
pin #8 = 0V
pin #9 = No reading
pin #10 = No reading
pin #13 = 0V

[mon2]

PU301:
pin #1 = No reading
pin #2, #3, #4, #5 = 19.63V
pin #6, #19, #20 = 0V
pin #9 = 0V
pin #11 = 4.5V ; ENLDO_3V5V
pin #12 = No reading ; ?? - measure the voltage to ground here
pin #13 = No reading ; ??
pin #14 = 0V
pin #17 = 0V

Board is attempting to enable the LDO yet pin #17 LDO output is @ 0 volts. Either the LDO regulator is defective or overloaded with a short condition.

Remove all power -> meter in resistance mode -> measure the resistance to ground on pin # 17 (+3VLP) LDO pin on PU301. Post the measurement.

Repeat the voltage measurements to ground on PU501 -> the board is requesting to enable the LDO using pin # 5 but you missed measuring pin # 9 LDO output. If the voltage is 0v, list it as such. Then remove all power and measure the resistance to ground of this pin as well.

So far, it appears that PU301 is defective but will confirm with your test results.

[Growtopia Jaw]

PU301:
pin #17 to GND = 24.95k ohms

Sorry, by "No reading", I meant to say that the values are "floating" like when digital multimeters aren't connected to anything and the values just float around sometimes in the positive and negatives. Simply put that the probes aren't getting any values from the connection sort of like an "open circuit".

When I get a 0V measurement, the display will hold at 0V at least for a few seconds and respond to changes whenever I lift up the positive / negative probe to indicate they are really 0V.

I've remeasured PU501's pin #9 to GND and got "over limit / O.L" even in the highest range (M ohms / AUTO). Voltage of PU501's pin #9 is also "No reading".

[mon2]

To confirm, check the LDO output pin with your meter in DC volts (10 volts or higher scale is ok since we know it should be 3v3 or 5v0) - black meter probe to ground; red meter probe on this LDO output. You must have a stable voltage reading here. If not, the regulator is defective. We know that the motherboard is wanting to turn on the LDO rail but the output rails are not to the specification.

[Growtopia Jaw]

I measured PU501 like this, meter in DCV mode -> turn on and connect adapter -> black probe on GND -> red on pin #9 PU501. I've also measured the same linked lines of pin #9 just to confirm whether the readings are consistent (See yellow marked box below for same lines of PU501's pin #9). As before, I got "No reading" for said pin.

Original unedited image:



Procedure:

[mon2]

Good pics. It appears that PU501 is not even stuffed on this board build. Instead, PU502 takes the place of the PU501 device. Proceed to measure the LDO rail @ pin # 14 to ground on PU502. Also measure pin # 15 on PU502. These should be ~5 volts if the LDO is working.

[Growtopia Jaw]

PU502:
pin #14 = 0V
pin #15 = 4.9V

[mon2]

Good. To me, at this time,summary is that PU301 is defective since the LDO enable pin for this regulator is a logic '1' yet the LDO output is not 3v3. If the resistance to ground of this LDO is not too low - it must function unless it is defective. This +3v3 rail is required to power the EC controller which is often a 8051 microcontroller used for the keyboard scanning and other tedious functions (RTC, etc.) -> only if the EC is powered and working will the LDO for the heavy current rail +5VLP_5V_8A on PU502 be enabled. Since the EC is not being powered, it is to be expected that pin # 14 on PU502 is @ 0 volts.

If you are shopping on Aliexpress, consider to order a few spares of PU301 and even a few pieces of the PU502 which should be inexpensive. However, it appears for now that PU502 is not defective.

Do pay attention to the full suffix of each part as it is important. I think that your charger IC is ok since the boosted voltage @ ASGATE is present. but if you are shopping - consider to pick up a few of the charger IC with the 'A' suffix (apparently there is even a version with a 'B' suffix - no idea on the differences). I think the SUHMS store has these parts or review if you have a donor board to borrow from. Just pick someone with a high positive scorecard. Do post your updates.

[Growtopia Jaw]

Sorry for the really long wait. I've ordered the chips SY8288BRAC_QFN20_3X3 (PU301) and SY8288CRAC_QFN20_3X3 (PU502) as recommended and it took about 2 months to arrive. Just had it soldered on just now (PU301). I haven't soldered on PU502 yet.

[mon2]

Looks good. You can use IPA (alcohol) with a cotton bud to remove the white residue around the joints.

[luyzs]

Good morning, I know this topic is old, but I have the same problem, I would like to ask a question.

I will buy the pu301 and pu502 components,

My question is whether the two are the same component, since in the electrical diagram the numbering is the same for both (SY8288CRAC_QFN20_3X3).

And the most important question is whether the repair worked.

thanks

[piernov]

SY8288B != SY8288C