Hello. I have problem with my LCD. Before repair screen showed up for a moment when lid was at 45 degrees. At 90 degrees there is no backlight. After few tries doesn't show at any degree. The flex cable from LCD backlight was broken (maybe make some short circuit). I've replaced whole LCD, and it still doesn't work. What should I check first to propertly diagnose and solve my problem? There is no image on external LCD. No sound, nothing. My mainboard is 820-00875A (nyks 94v-0 nm19).
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Macbook Pro A1708 820-00875A no image
- Thread starter proweb052
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First of all, welcome to the forum!
Did you disable the battery, before start the screen changing?
Post F7000 and L7210 voltage, w/ and w/o LCD connected.
Did you disable the battery, before start the screen changing?
Post F7000 and L7210 voltage, w/ and w/o LCD connected.
Did you mean disconnect battery from mainboard?
Good enough to disconnect data cable, J6951.
w/0 LCD
F7000 13,04V
L7210 0V
w LCD
F7000 13,04V
L7210 0V
And I did disconnect the battery before start screen changing
Actually CPU core is not powered.
Check if you get voltage on other big coils.
Check if you get voltage on other big coils.
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Did you test the board alone on the desk?
Don't connect anything, apart of charger.
Check for knocked of components, or broken trace.
Don't connect anything, apart of charger.
Check for knocked of components, or broken trace.
You can't get video, nor other life sign, without CPU core (VCORE) present.
We don't know if you lost VCORE before replacing the screen, or just after changed it.
As VCCSA (L7370) is present, VCORE should come on too; being controlled by same U7100.
If not, you may have problems with PCH/CPU, BIOS, or some broken (ripped off) component, or trace.
We don't know if you lost VCORE before replacing the screen, or just after changed it.
As VCCSA (L7370) is present, VCORE should come on too; being controlled by same U7100.
If not, you may have problems with PCH/CPU, BIOS, or some broken (ripped off) component, or trace.
This is not an exact science.
If machine was working before you start changing the screen assembly, then very likely the damage has been done in the process.
Do not quote an entire post, visible few centimeters above.
Maintain forum aesthetic, please.
If machine was working before you start changing the screen assembly, then very likely the damage has been done in the process.
Do not quote an entire post, visible few centimeters above.
Maintain forum aesthetic, please.
Post voltage for L7370, L7730, L7900/30/60, L8030/60.
Also check output voltages from page 64.
Just in case, check again L7210/20.
Also check output voltages from page 64.
Just in case, check again L7210/20.
L7370 - 1,04V
L7730 - 1,05V
L7900 - 1,00V
L7930 - 1,79V
L7960 - 0,94V
L8030 - 1,19V
L8060 - 1,00V
L7210/20 - 0V
U8200
Vout1 - PP1V8_S0 - 1,79V
Vout1 - PP1V8_S3 - 9,21V
U8205
Vout1 - PP3V3_S5G - 3,3V
U8210
Vout1 - PP3V3_S4 - 3,3V
Vout2 - PP5V_S0 - 5,1V
U8220
PP3v3_S0 - 3,3V
L7730 - 1,05V
L7900 - 1,00V
L7930 - 1,79V
L7960 - 0,94V
L8030 - 1,19V
L8060 - 1,00V
L7210/20 - 0V
U8200
Vout1 - PP1V8_S0 - 1,79V
Vout1 - PP1V8_S3 - 9,21V
U8205
Vout1 - PP3V3_S5G - 3,3V
U8210
Vout1 - PP3V3_S4 - 3,3V
Vout2 - PP5V_S0 - 5,1V
U8220
PP3v3_S0 - 3,3V
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"U8200
Vout1 - PP1V8_S0 - 1,79V
Vout1 - PP1V8_S3 - 9,21V"
Are you sure about this?
Vout1 - PP1V8_S0 - 1,79V
Vout1 - PP1V8_S3 - 9,21V"
Are you sure about this?
What is the exact ohm resistance to ground at L7210?
If no broken component, or trace, then bad CPU.
Just in case, try known good BIOS...
Just in case, try known good BIOS...