MBP Santa Rosa a1226 Display issues.

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Hi everybody.

I have a problem with my MBP since around 6 weeks ago.

Basically, the LED backlight doesn't work at all, which is quite a pain. I closed the lid once and when I came back to work on it again the screen wouldn't lit up again.

This screen i have right now with this issue is the second one i have on this laptop. The original one got smashed last winter and broke the LCD, so I bought this one thru ebay and replaced it myself. It has been working without trouble until now.

So I started doing some research about what could be the cause of the problem, thinking it could be a faulty graphics card, as reported by apple, some of this NVIDIA GeForce 8600 were faulty, but my external display works fine, so it's not that.

Then, a few days ago, I decided to open the laptop to replace the LED strip that lights up the screen with the one of my old screen and realized how complicated it was, so I started doing several tests with the 2 screens and parts.

Basically, I've tried both screens with both cabling sets, independently and mixing cables from both screens, the 2 LED driver boards, etc... All possible combinations, but none of the LED backlights will light up; neither on my old screen nor the new one.

I would be really surprised if both LEDs are broken, or both LED driver boards are faulty, or all cables are wrong...

So I'm a bit lost right now. The only 2 things I can think of are either the sleep magnet is stuck, but i doubt that's the problem as I'm writing this from the actual laptop with a desk light at the back to be able to see, or something within the logic board and the mains distribution to the actual led board.

So the next thing I want to check is the mains circulation across the whole circuit until the actual LEDs, with a voltmeter, but I don't know what's each pin on each connector and cables to avoid any short circuits are and what figures should I expect on my measurements.


Can anyone help me on this?

Or do you think there might be another cause for this problem?

Thanks in advance.
 

chscag

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Your Mac's Specs
2017 27" iMac, 10.5" iPad Pro, iPhone 8, iPhone 11, iPhone 12 Mini, Numerous iPods, Monterey
You're going to need a service manual in order to check voltages and find the right pins and connectors. Apple service manuals are available on the web but they're costly and sometimes wind up being a poor Xerox copy.

My suggestion is hunt around - perhaps on eBay - until you can find a service manual at a decent price. Otherwise it may be more cost effective to find a refurbished logic board and swap it out. The problem with that solution is that even refurbished Apple logic boards can be expensive.
 
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Thanks chscag,

I will keep my eyes open for that service manual.

I looked at some prices for logic boards too and I don't want to replace it. I even asked a few days back at the mac store how much would it be to get a new logic board or a new display, and they both came just a bit cheaper than a macbook air. Ridiculous.

If that's the case I might have to get a new one... booooo! I don't really want to do that, as this one works perfect. I might just have to take it around without the display's back cover and carry everywhere a big flashlight. jajajaja

Thanks for your guidance again chscag, much appreciated.

And, if anyone else has something else in the back of there heads to share it, it would, again, be much appreciated. Anything that could help me solve this matter.
 

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