A2338 no backlight.

[madrefoca534]

Hi everyone, back on the forum. I need your help. I have an A2338 that's driving me crazy.

Here's the story.
I bought this machine with screen problems. I noticed the flex cable and the connector on the tcon board were burned out. So I replaced the flex cable and tried it with a working LCD from another machine.
The device turns on perfectly, but there's no backlight. I can see the image in the background.
PPVOUT_LCDBKLT is 50V. I need to know what else to measure. I've already measured everything, and I've read Backlight Troubleshooting on LogiWiki (I learned a lot). But I still can't get the screen to turn on. Please help.

 

[2informaticos]

Usually 50V means no connection to LED strips.
Sometime this issue may be solved by DFU restore; if no electronic problem is found.

First check continuity between MLB and T-CON board.
You may have bad video connector on the MLB (JP600), or broken trace.

 

[madrefoca534]

Thanks for answering.
I've measured all the connector lines on both the motherboard and the flex cable. Nothing unusual at all.
I did find a data line shorted to ground. The UD050 chip, pin 4 goes directly to the CPU. I removed the chip and the line is still shorted to ground. I2C_DISP_BKLT_SDA. I don't know if this line has a direct impact on the backlight circuit. If so, there's nothing else I can do. Any advice?

 

[2informaticos]

Is the data line for backlight control; between CPU and T-CON.
I don't think changing CPU is an option; better to buy another machine.
You can still use this one with an external monitor/TV.

 

[madrefoca534]

No way, I'll use it for spare parts. I know the keyboard, trackpad, battery, speakers, microphones, etc. are all working. So, thank you very much for your assistance. As Dr. Polo would say, case closed. Hahahaha