Need help with one more board. 820-00165 with slight liquid damage around U8005 and U7701. Machine gives a chime and shuts off immediately. In fact it’s just half a chime and it shuts off. After cleaning liquid damage, I get a fan spin but it shuts down after few minutes. PP5V_S4RS3 is at 5.11v when it starts and drops to 0v and machine stops. Any suggestions?
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Macbook Air 820-00165 shuts down after half chime.
- Thread starter arshees
- Start date
Do you still get chime?
What about image/backlight and USB activity in these minutes?
Try starting in SMC bypass mode.
What about image/backlight and USB activity in these minutes?
Try starting in SMC bypass mode.
You should always try Google first.
It is also explained on many threads of the forum.
You can save time in this way...
boot in smc bypass mode - Buscar con Google
www.google.com
It is also explained on many threads of the forum.
You can save time in this way...
Got it booting and running but now stuck at no backlight. Confirmed dim apple logo and password screen is also visible but dark and no backlight. Liquid damage and minor corrosion seen around U7701. Cleaned it but no luck. 8.57v on fuse and on backlight output.
Measure the VIN voltage through capacitor C7710, the value is 5V, Measure the VDDIO voltage through capacitor C7711, the value is 3.3V, Measure the EN Pin voltage at the 2 Pin of the resistor R7731, the value is 2.8V, Measure the PWM Pin voltage at the 2 Pin of the resistor R7704 , the value is 2.29V, Measure the SCLK voltage at the 2 Pin of the resistor R7753 , the value is 3.3V, Measure the SDA voltage at the 2 Pin of the resistor R7757 , the value is 3.3V.
All voltages seem ok except PWM which should be 2.8v but shows 2.29v. Should i replace U7701 or can you suggest any other checks.
Measure the VIN voltage through capacitor C7710, the value is 5V, Measure the VDDIO voltage through capacitor C7711, the value is 3.3V, Measure the EN Pin voltage at the 2 Pin of the resistor R7731, the value is 2.8V, Measure the PWM Pin voltage at the 2 Pin of the resistor R7704 , the value is 2.29V, Measure the SCLK voltage at the 2 Pin of the resistor R7753 , the value is 3.3V, Measure the SDA voltage at the 2 Pin of the resistor R7757 , the value is 3.3V.
All voltages seem ok except PWM which should be 2.8v but shows 2.29v. Should i replace U7701 or can you suggest any other checks.
"All voltages seem ok except PWM which should be 2.8v but shows 2.29v."
Do NOT make wrong assumptions so easy!
There is PWM signal and varies with the brightness level.
Did you check XW7720?
If OK, change U7701.
I bet A5 ball is corroded...
Do NOT make wrong assumptions so easy!
There is PWM signal and varies with the brightness level.
Did you check XW7720?
If OK, change U7701.
I bet A5 ball is corroded...