MacBook Pro A1990 Question mark folder repair and MacBook Pro A2251 20V on USB-C, 0.00-0.01A current draw repair: Difference between pages

MacBook Pro A2251 20V on USB-C, 0.00-0.01A current draw repair
Device	MacBook Pro A2251
Affects part(s)	Motherboard
Needs equipment	multimeter, soldering iron, soldering station
Difficulty	◉◉◉◌ Hard
Type	Soldering

Latest revision as of 15:28, 29 October 2023

This article is a stub. You can help Repair Wiki grow by expanding it

Problem description

Dealing with a MacBook (820-01949) showing 20V on USB-C with a current draw of 0.00-0.01A.

U7800 (Figure 1) -- No image yet. Help expand this page by uploading it

R8050 (Figure 2) -- No image yet. Help expand this page by uploading it

Symptoms

MacBook displaying 20V on USB-C ammeter
Current draw registering 0.00-0.01A

Solution

Diagnostic Steps

Check PMU (U7800) Input

Verify if PMU U7800 (Figure 1) is missing 12V input (PMU_VDD_HI) caused by R8050 (Figure 2) being blown or corroded.
Check resistance on R8050; normal value should be around 877kΩ.
Note: R8050 is part of a voltage divider circuit, so voltage will be lower on pin 2 of the resistor.

Repair Steps

Blown R8050 with Short to Ground

If R8050 is blown and there's a short to ground on pin 2, replace both U7800 and R8050.

Blown R8050 without Short to Ground

If R8050 is blown but no short to ground is found, replace R8050.

@@ Line 1: / Line 1: @@
 {{Repair Guide
-|Device=MacBook Pro A1990
+|Device=MacBook Pro A2251
 |Affects parts=Motherboard
-|Needs equipment=multimeter, soldering iron, soldering station, thermal camera
+|Needs equipment=multimeter, soldering iron, soldering station
-|Type=Soldering, Software
+|Type=Soldering
 |Difficulty=3. Hard
 }}
 {{stub}}
+== Problem description ==
+Dealing with a MacBook (820-01949) showing 20V on USB-C with a current draw of 0.00-0.01A.[[File:Placeholder_image.jpg|thumb|U7800 (Figure 1) -- No image yet. Help expand this page by uploading it]]
+[[File:Placeholder_image.jpg|thumb|R8050 (Figure 2) -- No image yet. Help expand this page by uploading it]]
-==Problem description==
+== Symptoms ==
-Question mark folder, no external boot possible & Recovery does not work on A1990 MacBook
+* MacBook displaying 20V on USB-C ammeter
-[[File:Placeholder image.jpg|thumb|Example image (Figure 1) -- No image yet. Help expand this page by uploading it!]]
+* Current draw registering 0.00-0.01A
-==Symptoms==
-*Question mark folder
+== Solution ==
-*No external boot possible
+=== Diagnostic Steps ===
-*Recovery does not work
+==== Check PMU (U7800) Input ====
-==Solution==
+* Verify if PMU U7800 (Figure 1) is missing 12V input (PMU_VDD_HI) caused by R8050 (Figure 2) being blown or corroded.
-- Check U9080, U9580, U9000 & U9500 and SSD power rails PP2V5_NAND_SSD0, PP2V5_NAND_SSD1, PP0V9_SSD0, PP0V9_SSD1, PP1V8_SSD0, PP1V8_SSD1
+* Check resistance on R8050; normal value should be around '''877kΩ'''.
+* Note: R8050 is part of a voltage divider circuit, so voltage will be lower on pin 2 of the resistor.
-- Flash T2, Update Intel Mac T2 BridgeOS Firmware, Boot Mac into DFU Mode Then Reinstall MacOS Via Recovery CMD R
+=== Repair Steps ===
+==== Blown R8050 with Short to Ground ====
+* If R8050 is blown and there's a short to ground on pin 2, replace both U7800 and R8050.
+==== Blown R8050 without Short to Ground ====
+* If R8050 is blown but no short to ground is found, replace R8050.