DA00P2MB6D0 REV D Missing 3v5v LDO

[Tend0]

Hello everyone! Happy New year to all, cheers to new beginings and exciting adventures ahead!
I have a issue with this motherboard all voltage on charger ic are good and 3v5v ic's are suplied but not activate to deliver 3and 5v
i need our help to find a solution
i joint below shematic, brd and 3v5v datasheet
Thanks
[Mod. Edit]
Schematic and boardview -> https://www.badcaps.net/forum/troubl...01#post1418201
Reminder: rules and organization of this section
https://www.badcaps.net/forum/showthread.php?t=117483

[mon2]

Have not reviewed the schematics because need to fix our car's fog lights. Remove all power and check the resistance to ground of these missing rails. Post the measurements. If they are not low, check the voltage to ground of the enable pins for each.

[Tend0]

Thanks for reply
resistance to ground on pc43 (+3VS5) = 15,5 K
resistance to ground on pc43 (+5VS5) = 64 k
+3VPCU= 33k
+5VPCU=175k
Voltage to ground enable pin;
PIN 11 EN2 (PU10) = 0V
PIN 11 EN2 (PU11) = 0V
Multimeter UNI-T UT890C

[mon2]

Ok. Enables are not correct to enable the LDO rails. The enables function with a resistor based voltage divider. They accept a high voltage (adapter raw voltage of ~19v) and lower it to a safe value for the ENable pins.

Each works with the +VIN pin. Carefully measure the voltage to ground of the +VIN power rail which is the voltage after the DCin mosfets.

If +VIN is not ~19v, proceed to measure the voltage to ground readings on the charger IC:

ACDRV (pin #4)
ACPRES (pin #5)
REGN (pin # 16)

[Tend0]

voltage after the DCin mosfets ( PR57 ) 19.56V

ACDRV (pin #4) 25.03V
ACPRES (pin #5) 3 V
REGN (pin # 16) 6V

[mon2]

Then either pr57 is defective or the trace to this enable pin is broken. Remove all power. Meter in resistance mode.

measure the resistance on each side of pr57. Next measure the resistance from the left side of pr57 that is confirmed to have the ~19v and to the enable pin on the regulator.

update: another possibility is that the enable pin is being pulled or shorted to ground. Measure the resistance to ground of this enable pin with no power.

post all measurements.

[Tend0]

Measurement on PIN 1 of PR57 is not constant with a caliber of 600 Mohm it start at 4.12Mohm and decreases
on PIN 2 of PR57 is constant = 143 kohm.
resistance from the left side of pr57 to the enable pin on the regulator is not also constant with caliber set to 600K start 121k andincrease
enable PIN 11 to ground is 102K

[mon2]

Pr57 appears to be defective. Apply flux with low air pressure and use tweezers to carefully remove this part. Do not lose the resistor.

measure the resistor when it is cooled off and on your work table. It should be ~499k ohms and stable. If not the part should be replaced.

check the enable pin of the other power rail in the same way.

the parts are inexpensive so order spares and recommend to also order the other resistor (pr59) on the enable pin. Post each measurement.

[Tend0]

OK I will do it tomorrow thanks

[Tend0]

pr57 = OL on 600k calibre
pr3264 = OL
so what can be cause these resistor defected it's my first time to face thes issue on laptop motherboard, verry glade to learn more.

i don't know resistor part size to order it's verry smal. how can find size?

there is way to force enable pin with wire jumping?

thanks for our support

[mon2]

https://www.digikey.ca/en/resources/...oltage-divider

with 499k and 150k + 19v as in the input voltage; the EN pin was to receive ~4v4 to enable. Be sure to study this area for possible corrosion / liquid damage. Share clear pictures of these 2 parts for this regulator and also the other that is not working. We must be sure that the proper pin (EN) is being reviewed.

If indeed these 2 parts are defective, you can consider to apply a piece of wire from this EN pin or resistor pad onto the REGN pin of the charger IC. That is, when the charger IC is being powered, the REGN pin will be 6v and this 6V can then be used to enable this regulator. The same 6v should be fine to enable the other regulator. This is only a suggestion but the best one is to replace these parts. If you do this, the 499k resistor should be removed off the logic board for each regulator.

It is strange that BOTH resistors on the 2 different regulators are damaged. Do post clear pics of all these resistors before proceeding. The parts are most likely 0402 or 0603 in SMD size and each are inexpensive to source. The REGN bypass trick should work fine as long as the regulator EN pins are not being shorted which they do not appear to be based on your past resistance to ground checks. Be sure to use a very fine piece of wire that is insulated and low enough heat to melt the solder - too much heat will destroy the PCB pad. Too low of a wire gauge will tear the SMD pad off the logic board = each will be a messier repair job to fix.

[Tend0]

all test with enable pin to each +vin resistor pin are good

[mon2]

What is the voltage to ground on PU11 (pin #11 = EN2) ? Next, remove all power and measure the resistance across the resistor @ PR3264. What is the measurement? From the BV files, these are the proper locations for these resistors and matches your last post.