Fix Your Stuff Community Store

13" aluminum unibody, 2.0 or 2.4 GHz Core 2 Duo processor.

574 Questions View all
Question Closed

Options

No backlight, desktop visible with flashlight, external works

Hi there,

I saw a similar post but couldn't find any relevant answers apart from the standard troubleshooting suggestions.

As the title reads, my Macbook is working fine with an external display and I can see a faint desktop on the internal screen if I use a flash. I've tried SMC & PRAM. The screen has been replaced as well.

I tried changing to a new logic board, but unfortunately the one I bought off eBay didn't work at all, no power, nothing so that was a downer.

I read --here --that one could measure the resistance/ Ohm on a particular fuse which is highlighted on a picture there, I tried that and it reads about 350-400Ohm on the one that is circled. I don't know whether this is normal, I checked on the other logic board that I ordered ( which was faulty) and it read about the same on this fuse. Checking other fuses they vary between 0, 100, 150, 200, 300. So I'm not so sure its a fuse issue either. It's somewhat confusing though that not all fuses show 0, or perhaps some of them are made to have a resistance?

Can you help me figuring out whether its a fuse-issue or a bad QFN chip, which fuses should I look at? And if its not the fuse(s) can I get hold of a QFN chip somewhere for this board? I believe its the "APP001" that runs the LCD am I right?

Hope you can shed some new light on this for me

Kind regards

EDIT:

The QFN i referred to is called APP001, 592.4T, 0823A

According to previous post the fuse should be a 2A, 32VDC Quick Blow

Macbook Late 2008, 5.1. Serial: 34841N3M1AQ (I think, found in "About this mac"

Update (01/15/2016)

Thanks for your quick reply, hehe yeah I'm aware of that :-)

The logic board is a 820-2327-A.

See pictures.

Block Image

Block Image

The one showing the backside (with the GPU, CPU) is the same model (although faulty with no power) but it should look the same and thought it might prove useful.

Answer this question I have this problem too

Is this a good question?

Yes No
Score 0
2 Comments

viktornordahlbacklund you are a bit all over the map:-). Post some images of your logicboard with your question so we can point some places out that you should test. It will also help if you can tell us what the 820-XXXX logic board number on your board is. To check the fuses checkthis site to see how to do that. You test your SMD fuse the same way as pointed out on that site. To add images to your question use this guide

Adding images to an existing question

by

Please see update above with the pictures and added info.

(Originals should be high-res)

by

Add a comment

1 Answer

Filter by:
Most Helpful Newest Oldest
Most Helpful Answer

Options

viktornordahlbacklund here is the location of the backlight fuse. It is a 2A 32V in a 0402 package. Start by checking that for continuity. Remember there is always a reason why it fails, so you will have to check for short circuits etc. Make sure that you check your LCD connector to ensure you do not have a short on that part.

Block Image

Was this answer helpful?

Yes No
Score 3

6 Comments:

Thanks, I'll have a look at that fuse as soon as I get it picked apart again!

The LCD connector is the one on the backside right, the one in the upper right corner (when opened and laying top-down) next to the magsafe connector?

How would I go about checking that for continuity, at what point(s)?

by

Yes. unplug it and see what the connector looks like. Use a magnifying glass to see the points etc. You can use a multimeter to check for short circuit. I'll send you a link that will help you with that.

by

Did you find the link describing the process of checking the LCD connector?

by

Check these videos

by

thanks, couldn't find my specific logic board there among the videos (in the backlight section), but do you mean the others might hint at what to do as well?

Otherwise if you know what specific points/ circuits are relevant for the backlight on the 820-2327-A please feel free to point these out/ draw on the pictures I added, I'm kind of a newbie at this sort of stuff so find it a little difficult to know where to begin.

Btw, it could be the APP001 QFN package too right? I've read these are really hard to get..

by

Show 1 more comment

Add a comment
View Statistics:

Past 24 Hours: 0

Past 7 Days: 0

Past 30 Days: 0

All Time: 379