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820-01949 Stuck at 5V

C

CGid

Member
Macbook A2251 came in for liquid damage.

After inspecting the board there was noticeable corrosion on the motherboard around the battery connector area.

Board was ultrasonic cleaned.

After cleaning a short was found on PPBUS_G3H. Injecting voltage showed U7600 was shorted. Replaced from a donor board and the short is cleared.
System still stuck at 5V pulling 0.002-0.007A.

PPBUS_G3H voltage - 0.616V

Checked ISL chip and ISL is not getting any voltages to it.
Found that R7020 and a few components around it needed swapped. Swapped components. Now have 1.054V on PPBUS_G3H. I get 5V going to ISL (pictured here with voltage readings
https://imgur.com/a/wPAnOKe
)

Does ISL need replaced too? I checked at R6907 for Voltage and get nothing.
 
2informaticos

2informaticos

Administrator
Staff member
Do you really expect that someone else identify the lines in the picture and translate to schematic?
Please, post usefull information, when need help.

Remove F7000 and check C7050 voltage.
 
C

CGid

Member
Sorry, didn't think that was a big ask when it comes to board help but will make sure to change that when posting in the future.

@ C7050 with the Fuse removed I get a cycling voltage from ~2V down to 0.9V then back up to 2. Would say it's a 2-3 second cycle.
 
2informaticos

2informaticos

Administrator
Staff member
Keep te fuse removed, until solve U7000 problems.
Post U7000's basic voltages: P_IN, AUX_DET, SMC_RST_IN, VDDA/P, EN_MVR, A/BMON.
Check resistance (ohm scale), over C7020/23.
 
C

CGid

Member
U7000:
P_IN - 5.087V
AUX_DET - 1.263V
SMC_RST_IN - 0V
VDDA - 5.062V
VDDP - (-0.069V)? Black probe was on ground but still got negative symbol.
EN_MVR- 0V
AMON - 0V
BMON - Starts @ 0.893V, drops to 0V within a second or two. Repeats.

C7020 - 493.6 kOhms
C7023 - 2.3 Ohms
 
C

CGid

Member
how? I changed C7020/61/62 but still have the same resistance present. Do I need to remove the ISL chip? Or do I need to step back and replace Q7040?

Edit: Replaced Q7040 still no change. Thinking to pull the ISL but don't want to if I'm looking in wrong area. R7061/62 measure good.
 
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C

CGid

Member
Can you tell me what reading I should expect on C7020?

Edit: Fixed broken trace under R7060, now have 2.7 Ohms across C7020.

Now
U7000:
P_IN - 5.087V
AUX_DET - 1.263V
SMC_RST_IN - 0V
VDDA - 5.062V
VDDP - (-0.080V)
EN_MVR- 0V
AMON - 0V
BMON - 0V No cycling now

C7020 - 2.7 Ohms
C7023 - 2.3 Ohms
 
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C

CGid

Member
Replaced R7075 as well as a few other poor looking caps by it. Now I have 5.062V on VDDA/P as well as EN_MVR

U7000:
P_IN - 5.087V
AUX_DET - 1.263V
SMC_RST_IN - 0V
VDDA - 5.062V
VDDP - 5.062V
EN_MVR- 5.062V
AMON - 0V
BMON - 0V

System is now at 5V drawing ~100mA instead of 2-5mA

Voltages around U7000 now
https://imgur.com/a/eM2PHgn
 
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C

CGid

Member
So I had those readings. Unplugged the board and walked away. Now when I plug in the board I only get a 15-20mA draw.

VDDA is only 2.3V now. VDDP is only 2.6V now, resistance to ground is 171 Ohms. EN_MVR is 0V, resistance to ground is 4.520 MOhms

Measuring across R7075 i get 4.8 Ohms

U7000:
P_IN - 5.087V
AUX_DET - 1.263V
SMC_RST_IN - 0V
VDDA - 2.366V
VDDP - 2.633V (Diode Mode: 0.180V)
EN_MVR- 0V
AMON - 0V
BMON - 0V

ISL IC is showing smallest bit of warmth under thermal camera.

https://imgur.com/a/VjuOaHe
 
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C

CGid

Member
These are readings without f7000 installed. Whatever caused me to have the voltages present is no longer functioning properly.
PPBUS_G3H Diode Mode to Ground - 0.481V
 
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2informaticos

2informaticos

Administrator
Staff member
Remove C7075 and check again on its pads.
If still low (0.136), then replace U7000.
If good reading, then replace C7075.

BTW, stop writing "V" for diode mode readings.
 
C

CGid

Member
Will replace U7000 as reading is still low.
Am I wrong in it being "V"? I thought it was measuring voltage drop.
Does U7000 have to come from donor board or will brand new IC work? Just not sure if chip is programmed by any means.
 
2informaticos

2informaticos

Administrator
Staff member
New ISL9240 will work; if is good, of course.

Voltage shown by multimeter in diode mode, is caused by the constant current injected by itself.
Stop writing end "V"; avoid any confusion with real voltage, checked when the board is powered.
 
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