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[solved]820-3115 no video, backlight is working

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spakhnyuk

spakhnyuk

New member
I took readings from a working board as well to compare..

Here are reading from a working board:
PIN 8 - 0.353
PIN 9 - 0.353
PIN 10 - 0
PIN 11 - 0.353
PIN 12 - 0.353
PIN 13 - 0
PIN 14 - 0.353
PIN 15 - 0.353
PIN 16 - 0
PIN 17 - 0.353
PIN 18 - 0.353
 
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aprendiz

Moderator
Pin 15 is too low this goes strairght to PCH and pin 17 maybe L9080 is open this is why screen is not recognized...
 
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aprendiz

Moderator
spakhnyuk said:
I took readings from a working board as well to compare..

Here are reading from a working board:
PIN 8 - 0.353
PIN 9 - 0.353
PIN 10 - 0
PIN 11 - 0.353
PIN 12 - 0.353
PIN 13 - 0
PIN 14 - 0.353
PIN 15 - 0.353
PIN 16 - 0
PIN 17 - 0.353
PIN 18 - 0.353
Click to expand...

This are with screen plugged in???
 
spakhnyuk

spakhnyuk

New member
I didn't disconnect the screen so the previous good board LCDS diode mode readings were incorrect.
Here are the CORRECT GOOD BOARD READINGS:
PIN 8 - 0.600
PIN 9 - 0.601
PIN 10 - 0
PIN 11 - 0.600
PIN 12 - 0.601
PIN 13 - 0
PIN 14 - 0.602
PIN 15 - 0.602
PIN 16 - 0
PIN 17 - 0.605
PIN 18 - 0.606
 
spakhnyuk

spakhnyuk

New member
I'm getting voltage on 4 pins of L9080 (about 1.5V)
The traces between PIN 17,18 and the L9080 are good as well
 
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aprendiz

Moderator
Check coil L9080, you should have continuity between pin 1-2 and between 3-4, as you say "PIN 17 - OL" my guess is there is no continuity on pin 3-4 from L9080, so, coil is bad and for pin 15 you say "PIN 15 - 0.187" this value is too low so may guess is a bad PCH.....
 
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dukefawks

Administrator
This is a dead PCH. Replace PCH and see if LCD works again. After that you will need to write a BIOS with clean ME!
 
spakhnyuk

spakhnyuk

New member
aprendiz, I had the U1800 pulled on on my schematic for the record. Just wanted to confirm. I've only been doing board repair for a 3 weeks so I appreciate your help!
Bear with me please while I learn the common references :D
 
larossmann

larossmann

Administrator
Staff member
For full disclosure, for all people subscribed,

Duke and I, at this time, are the only people to whom the $$$ from your subscription fees go to. Part of what you're paying for are our answers(past and present), and part of what you're paying for is for us to not troll the shit out of you. ;)

Anyone not being compensated to troll the shit out of you... might troll the shit out of you. :D

Do you have a BGA rework machine?
 
spakhnyuk

spakhnyuk

New member
Haha no worries Louis! I think this community is awesome. Everybody so far has been extremely helpful. Some questions definitely deserve trolling!


I do not have a BGA rework machine. After seeing the the size of the U1800, I think this may be a project for another day once I get proper equipment.
 
larossmann

larossmann

Administrator
Staff member
IMO BGA rework in 2016 is a waste.

In 2006/2007/2008 before Apple recalled the A1226/A1260, at the heydey of the NVIDIA issues, you could print money on BGA rework.

Now it is just a bunch of money to invest in something you use every now and then. What if the PCH you bought was dead? What if it was something but the PCH? You invest an hour of your time and $30-$50 into a repair that may not even work, that's after investing thousands into a BGA machine and countless hours fucking with it to figure it out.
 
spakhnyuk

spakhnyuk

New member
Thanks for the advice Louis. This board will go into the unrepairable pile for me. Thanks for all the help everyone.
 
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dukefawks

Administrator
I would be interested in buying the board off you if you are going to scrap it! Always in need of 3115 boards.
 
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