[SOLVED] 820-00138 A1398 not switch on after short from charger, what charger does it need?

[2informaticos]

Isn't your board similar to 820-00163?
That one has boardview file...
I saw refferences on Internet as 820-00138 and 820-00163 fro same Venus X245G logic board.

 

[leonattpcs]

Hi,
I got the board view file and they are different boards, but it did lead me to the faulty component. R7120 was burnt out. I replaced it from a MacBook Air board. With the board in the computer, and power connected, it gives a green then red light, logic board gets warm as though it is charging from a genuine Apple charger. It switches on and gives fan spin then the happy tone, fans keep spinning, but nothing appears on screen. So now I am working back from the screen connector to find out what is going on there.

 

[2informaticos]

Put same 20miliohms at R7120; to avoid any future problems.
10miliohms will work too, but current sense reported to SMC will not be correct...
Hope you solve the backlight issue fast now.

 

[leonattpcs]

If I find the very same component I will use it. I don't know if it is backlight or graphics issue, but I an looking for voltages at the moment.

 

[larossmann]

Put flashlight through the back of the screen to see. Also realize this won't show you anything with 2012-2014 model LCD.

 

[leonattpcs]

Tried that a few hours ago with my iPhone flash. Didn't show a single ray of light through the apple symbol so I'm guessing it is the later version. It is a retina, I'm on another steep learning curve.

 

[leonattpcs]

Update on the no graphics issue, looking at the schematic pin 28 29 and 30 end up at U8300. Cannot find u8300 yet, but may have found U8330. Putting U8330 aside, pin 28 39 and 30 are shorted to ground, so is L8300 and, I am guessing everything that goes back to at least U8300. Looking for other voltages going to the lcd connector, there should be 3.3v going to pin 5. There is nothing there and it is not shorting to ground, any voltages tested up to now have been tested with lcd connected nd disconnected.
Still looking

 

[jason_microsoldering]

Find the short on PP5VR3V3_SW_LCD, there are only like 5 components on that line.

 

[leonattpcs]

Didn't notice there were so few, still looking for the component, but will do that tomorrow. Been at work for the last 14 hours, I have a cold and my head hurts so am going home.

 

[leonattpcs]

Oh goody, found the short only appeared when the screen was connected, looking at the connector the last pin is damaged so is that just a new cable? Does the cable go into the screen therefore the screen needs taking to pieces if that is possible?

 

[leonattpcs]

With careful placement I have managed to get the cable in despite the bent pin and now all is well. Switching on again and all fine. Movie uploading to YouTube as I type.