Hello friends, today i got an A2485 820-02100-A in a desd state, found visual short on PPVIN_5VUSBC23 line, removed tantalum capacitor, installed same same value from other donor board, now there is no short on any of the rails but when i plug either magsafe3 or usbc inget 5v stable with 0.00 amps drown, no cycle, just these steady values, board is not in dfu mode, checked with magsafe and with usbc. Only value that i find on the board is ppdcin_aon which is 5v… i dont get 3,3 aon, 3v8 aon .. all missing, where should i start looking please !
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Would u5700 be the issue ?! -
Remove all power. Meter in resistance mode.
What is the resistance to ground of PPBUS_AON_REG ?
Measure on each side of the fuses @ F5200 / F5201.Comment
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I get 0.560 MΩ on both fuses
i replaced u5700 also … same 0 amps drawComment
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CG801 was the blown capacitor if any helpComment
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No shorts here with such a high resistance.
What is the voltage to ground of PPBUS_AON_REG ?Comment
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only 0.3vComment
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What is the (input to the buck / boost regulator @ U5200) voltage to ground of PPDCIN_AON_CHGR ?
You can measure @ C5201 or C5202, etc.Comment
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5vComment
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Flux and carefully remove F5200 and F5201. This is to remove the downstream / consumer side of this power rail. There does not appear to be a short on the consumer side of the fuses but this step will isolate this regulator. Then power up again and measure the voltage to ground of PPBUS_AON_REG.
Do review U5200 for any possible damage or on surrounding parts. You can also post close up pics of this part.Comment
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0.02v and the u5200 is mint allaround it ..Comment
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Found something new just now, UD102 BLOWNAttached FilesPremium supporters get full download access and other benefits.
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This is the AHA moment
Not sure why it is damaged but will need to be fluxed and carefully removed. Be sure to allow ample time for the solder to be in liquid state.
This part is a level / voltage shifter for the SMBUS interface.Comment
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Looking now for donor boards that have this part… LSF0101-i2C
i can only find LSF0101-DRY i will check if same comonent trough the datasheets.. i dont have a 820-02100 for parts, this is a first… i will solder back the fuses and test againComment
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I think it is the same. The suffix is just Apple lingo to remind the viewer that this is used for I2C level translation.
LSF0101 1-Channel Auto-Bidirectional Multi-Voltage Level Translatorfor Open-Drain and Push-Pull Applications datasheetComment
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Yep, replaced also, still in the same state, steady 5v 0amps, so back where we have left …Comment
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What is the voltage to ground now of PPBUS_AON_REG ?
Test each USB Type C port -> same 5 voltage and current draw?
Rotate the USB Type C port by 180 degrees to test the bottom side of the USB C port's blade. Suggest that you unplug the main power from the wall so that the power adapter is discharged / dead -> insert onto your macbook -> then plug into the wall.
Same current draw on every port? The LDO rail of each 3217 should be reviewed to confirm the power delivery controller is functional. At 5 volts, the default power on voltage is being fed onto the logic board. The communication over the CCx pins has not taken place to dial up the VBUS rail to 20V.Comment
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Sadly i need to pause the all above for at least 8 hours since here its already midnight, my brain is fried at this point ... its nice that we create a stepby step guide to determine the solution of this issue. Many thanks for your patience, i will get back with you in 8-10 hrs !Comment
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I’ve managed to test all the 3127 and removed the 3128 just because i dont yet have one, inwas getting 1v3 on the ppbus_aon_reg tryed changing the UF800 just to be sure, same values on 0amps draw, 1,3 v inhave changed the raa489900 with isl9240 since from the schematics it looks the same, same result, i have replaced all the cd3127 just because i had them around, same result .. 5v 0amps the only thing that changed is the PPBUS_AON_REG that changed from 0,3 to 1v and easy increasing voltage up to 1,5…1,6v …Comment
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3217 and removed the 3218 - took a bit to figure this out. As far as I know, you cannot expect the power delivery (PD) circuits to operate unless each PD controller is functional and onboard.3127 and removed the 3128
Also, not sure if raa489900 = ISL9240 so best to keep that controller to the original or source one from a donor board / reliable store on Aliexpress.Comment
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Hello everyone,
I am new into this, sorry to post it here. I want to make this as a pet hobby project, as this mac is not urgent.
I have (Macbook Pro 13inch 2017mid) A1706 820-00923-A
My mac had liquid damage a long time ago, the connector from J8500 is damaged on pin 46 (PP5V_S0_ALSCAM_F), I guess the LCD/display panel is in short circuit, as I saw the connector from the LCD burned as well.
And the resistor L4004 is literally burned.
From what I see from the schematics, it does not affect any other rails, only the connection to the display... -
hello. I'm at a dead end. So, when flashing through dfu, I got an ssd error. I removed all the nand chips and u9000 u9080. As a result, I got 5 volts of consumption and everything is shorting - that is, it seems that all the contacts on the nand chips and yu9000 yu9080 are shorting to each other. Maybe there are a couple of units somewhere that don't short. and I don't know where to look next.
help09-12-2025, 04:14 AM -
Hi everyone,
I'm working on a MacBook Air 2020 (A2337, board 820-02016) and running into a strange USB-C issue. I've gone through quite a bit of testing and part replacement, but I'm stuck — hoping someone here can shed some light.
🛠 Original Issue
The machine initially wouldn't negotiate 20V over USB-C — stuck at 5V.
Diagnosis showed PP1V5_UPC0_LDO_CORE shorted to ground.
I replaced U3100 (UF400) using a donor board (A2179), and the machine powers on fine now.
⚠️ New Problem: One USB-C Port Only Works in One Orientation... -
Hello there,
I've got a Lenovo Legion 5 Pro 16ARH7H (AMD Ryzen 7 6800H, NVIDIA RTX 3070Ti) that seems to have "developed" a short on the 5V "Always-On" rail.
Background
I don't have too much in the way of useful information here, I don't think. This laptop has been used for the past few years without any notable issues/incidents. The laptop is often "docked" w/ the AC adapter (Lenovo's rectangle one) connected. A few days ago, I finished up working on things in the evening, and the next morning I found the laptop off w/o any... -
Good morning. I deliberately bought a motherboard in unknown condition, hoping it would work, but unfortunately, Murphy's Law worked as usual this time. Asus Tuf B360m-E Gaming motherboard. After connecting the power supply, the component marked B45PO3 lit up like a Christmas star, and the NCT5582D also overheated. After desoldering the B45P03, nothing heats up anymore, but there's a problem with a short to ground on the coil and in the area marked PO3001 on the board. I'm not sure if it's lines 3, 5, or the main power line.
Could anyone suggest where I should start looking for the cause...
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