Advanced Power Electronics Corp # AP3840CDT33
https://mpdf.jiepei.com/ap3840cdt33-47920858.html
mon2
Badcaps Legend
Last Activity: Yesterday, 08:15 PM
Joined: 12-15-2019
Location: Windsor, Ontario
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Remove all power. Meter in resistance mode. Measure the resistance to ground of the backlight rail that mates with the display connector. You are hunting for possible shorted caps on this rail.Leave a comment:
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Not familiar with this device but start with the obvious signals:
1) is the part heating up more than usual? Thermal camera will help here.
2) check the ALW power on rails - are they enabled? Present and within specification of their pin labels?Leave a comment:
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Post all pin voltages to ground on pu8900 with adapter and battery connected. Include the PIN numbers and their labels for easier reference.Leave a comment:
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When it does turn on and remains on, is the boot very slow?
https://www.ifixit.com/Answers/View/...+for+long+time.Leave a comment:
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Yes, agree that the mosfet in your pic is B12N03. Keep it simple, replace with the same parts that are onboard. Suggest to even order the PUB1 charger IC so that you have a full kit of parts to rebuild the region of the circuit if required.
So in summary - order the mosfets that surround this PUB1 charger IC & PUB1 charger IC. In my schematic PUB1 = BQ24781RUYR. Be sure to cross check against your actual logic board.
Review the silk screen text on your board. Is it LA-K861P? That is the schematic I am using for this review.
https://www.aliexpress.us...Leave a comment:
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Test the voltage to ground on the battery pack with the power adapter attached. Is the voltage higher than the marked battery pack voltage? It should be slightly higher than the battery pack voltage. If yes, the battery pack should charge unless it is defective....Leave a comment:
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Locate the power on/off button pads on the PCB. Use a pair of tweezers to short one pair to mimic the power button on the keyboard.
Does the board turn on and remain on with this method?
...Leave a comment:
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Review the voltage to ground for the following points of interest on the battery connector:
SMBUS_3V3_BATT_SCL
SMBUS_3V3_BATT_SDA
This case may be linked to corrupt T2 firmware:
(see last discussion)
https://repair.wiki/w/MacBook_Pro_A1...k_at_5V_repairLeave a comment:
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Hi. Got you PM. Continue to post here.
What is the voltage to ground of PPBUS_G3H?...Leave a comment:
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These parts are very inexpensive. You may even be able to find them on donor boards. From where do you plan to purchase these mosfets if not on your donor boards? Digikey / Mouser / Aliexpress? Will review the part numbers and get back to you. There are many other parts that can be used a replacement. No harm to also replace PQB2. These parts should be $2USD or less for each. Aliexpress will be the lowest price but highest quality from Digikey, etc.Leave a comment:
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Flux and replace both of these mosfets. Be sure to not turn on the board unless both mosfets are onboard. It takes both mosfets to be functional to properly dial up the target charge voltage. Based on the above, the low side mosfet is for sure defective but suggest to replace both of these parts.Leave a comment:
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You had replaced UD102 mentioned in the first post. It was replaced again or just needed a reflow?Leave a comment:
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Test each USB-C port and also flip the connector head by 180 degrees for similar testing. Remember that on USB-C ports, there is a top and a bottom half of connections. Only one side is active at anytime.
With the meter showing ~7mA consumption, hardly any load at all. Review the LDO rails of the local CD3217 power delivery controller. That is, each USB-C power has a local power delivery (PD) controller IC. That IC is a stand alone controller that hand shakes with the external power supply to switch to 20v when applicable.
For starters, each of the CD3217 controllers...Leave a comment:
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What is the voltage to ground @ F5200?
Remove all power. Measure the resistance across C5220 = checking the input current full path resistance.Leave a comment:
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Confirm the power rails on this level shifter @ UT360.
Any activity on the other signals on UT360 from the bus master?
Does this unit power up otherwise?Leave a comment:
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Silergy SY8288RAC = AWSxxx
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https://a.aliexpress.com/_msUal53Last edited by mon2; 09-23-2025, 05:30 AM.Leave a comment:
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