Macbook Pro 13" - 820-3115-B - No Backlight on Screen

patrickribbsaeter

New member
Hi, i have a customer computer who spilled juice on the keyboard. Some small areas have been cleaned on motherboard with isopropanol.

1. I have green light and FAN spin on motherboard.
2. NO CHIME
3. NO IMAGE

Any suggestions?

thanks
 

2informaticos

Administrator
Staff member
Normally an USB mouse should be good enough; but sometime is tricky.
Is better to use OSX on USB pendrive witk Link LED; if flashes, 100% USB activity confirmed.

VCORE voltage on L7510/20 coils.
Check if you get a drop from 1.15V to 0.75-0.8V after few seconds...
 

patrickribbsaeter

New member
Thanks for the excellent advice.

1. USB port is working fine with USB (LED is blinking).
2. L7510 i get 3.3v on both sides of the coil.

What now?
 

2informaticos

Administrator
Staff member
"L7510 i get 3.3v"
That is impossible!
If you have USB activity, board is working.
VCORE should be aprox 0.75V in this case.

Please provide accurate information...

Do PRAM reset and tell us if get chime at least.
 

patrickribbsaeter

New member
No Title

1. Tried pram reset,not working, No chime, only the sound from the fan spinning
2. The bord and fan spins but No image, i tried with another screen not working aswell
3. Q7510 (voltage divider) i also get 3v on the output on all 4 pins
 

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patrickribbsaeter

New member
Its correct now on:

1. Q7510 is 1.8v on output pins: 6,7,8.
2. Q7510 VIN is 12v.
3. L7510 is 1.8v on both input and output pins.

No voltage drop from 1.15V to 0.75-0.8V on L7510..
 
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2informaticos

Administrator
Staff member
You must check VCORE on pin 3 of L7510/20.
3V3 there will fry CPU.
If you really have USB activity, I repeat, VCORE should be aprox 0.75V...

BTW, don't talk about voltage divider on Q7510!
 

patrickribbsaeter

New member
1. Ok, wont mention voltage divider.
2. L7510/20. I cant find it on the schematics or boardview. Do i search correct like this: L7510/20. Shouldnt it not be only L7510 i search..?
3. the extension: /20.. What does that mean?
 

patrickribbsaeter

New member
I changed the battery now.

1. The DMM shows 1.6v on both L7510/20 on all 4 pins.
2. No voltage drop from 1.15V to 0.75-0.8V on L7510/20
3. Still NO chime.

Whats next?

4. I checked J9000 connector/LVDS ppv3v3_LCDVDD_SW_F on pin: 2 & 3 (Suppose to be 3.3v). I get NO reading!
 
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2informaticos

Administrator
Staff member
Are you sure about USB activity?
Do you have 1.6V from the first moment charger is plugged in?
Do you get any beep error without RAM?
Test if has external video.
 
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