First, remove the ground wire from BKLT_SD.
Post BKLT_SCL/SDA voltage and diode mode to ground.
Did you try another compatible LCD assembly?
Post BKLT_SCL/SDA voltage and diode mode to ground.
Did you try another compatible LCD assembly?
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820-00138-05, no backlight
- Thread starter Hardwood T/S
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Hardwood T/S
Member
BKLT_SDA - 4.46v, diode mode .443
BKLT_SCL - 4.54v, diode mode .445
Haven't tried another display yet, don't have one rn.
BKLT_SCL - 4.54v, diode mode .445
Haven't tried another display yet, don't have one rn.
Try PRAM reset 2-3 times.
Check LCD_BKLT_PWM_R DC level.
Check LCD_BKLT_PWM_R DC level.
Hardwood T/S
Member
PRAM reset had what looked like a small flash on the screen right after the first or second reset, but nothing afterwards.
LCD_BKLT_PWM_R - 3.2v
LCD_BKLT_PWM_R - 3.2v
Need to try another LCD assembly.
Backlight signals look good...
Backlight signals look good...
Hardwood T/S
Member
Got it working 
resoldered L7710 and Q7701, we have backlight.
Unfortunately, after a while of the board being turned on and functioning totally normally, the system hung for a moment and fans went up, and now the fans blare shortly after turning the computer on--classic PFM006, NDC001, PPN001. It's probably the I/O board cable as I saw it had some corrosion on one end--will replace and update with if it fixed.
resoldered L7710 and Q7701, we have backlight.Unfortunately, after a while of the board being turned on and functioning totally normally, the system hung for a moment and fans went up, and now the fans blare shortly after turning the computer on--classic PFM006, NDC001, PPN001. It's probably the I/O board cable as I saw it had some corrosion on one end--will replace and update with if it fixed.
Hardwood T/S
Member
New update: not sure if this is related or just a quirk of the issue, but the computer runs fine with only one fan installed. No slowdowns, no fan blurs, nothing. With both fans plugged in, however, the computer quickly picks up their speed and runs very slowly.
edit - now it's slow with one fan plugged in again. Confused as to why it's working differently some times rather than others.
edit - now it's slow with one fan plugged in again. Confused as to why it's working differently some times rather than others.
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Install HWMonitor and check for strange values of temp, or current.
Hardwood T/S
Member
Found that heatpipes #2 and #3 and outlet fan temp, all around 128C. Everything else was normal.
Hardwood T/S
Member
Does this indicate anything specifically? From what lines I see that are associated, none are shorted--though I didn't test their voltages yet. Will give a more detailed update when flatcable comes in.
Being liquid damaged board, I recommend you to reball SMC...
Hardwood T/S
Member
Flat-cable came in, no more whirs. Thanks for the help fellas, case closed!
Thanks for the help fellas, case closed!