820-3332-A no backlight

Eldafint

New member
Image works fine but I have no backlight. I replaced a burnt LCD connecter and cable thinking that'd fix my issue but it didn't.
I'm new to board repair so I'm quite lost at this point.

C9715 through C9719 and C9000 all short to ground and I can't figure out why.

Also I get no continuity over F9700.
 

2informaticos

Administrator
Staff member
Remove the caps one by one and check if short disappears; don't forget C9000.

Be sure no short underneath J9000.
Did you check its traces once the burnt connector was removed?

Post diode mode to ground at L9710 too.

BTW, write directly on the Reply box, instead of clicking Reply button.
I don't see any reason to quote an entire post, visible few centimeters above...
 

Eldafint

New member
I haven't started removing caps yet because I haven't had access to the tools.
However I did measure diode mode to ground on L9710 and it came out to 0.356.

Afaik there shouldn't be any shorts under J9000 and the traces looked good when I was switching it out.

Also should I not worry about the fuse not showing continuity?
 
Last edited:

2informaticos

Administrator
Staff member
F9700 must be replaced, of course.
But you cannot apply power on the board before eliminate the short; else the fuse will burn again.
 

Eldafint

New member
So I was gonna start lifting caps but was looking to start and noticed that my board seems to be missing WXD250? Or at least it's not located where the board-view files say it should be. I'm not sure it's at all integral to the repair but it really stumped me.

Do you have any suggestions on where to start removing components to make it easier?
 

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2informaticos

Administrator
Staff member
If ohm resistance of the short is low enough, you can find it with voltage injection method.
I hope you know how to do it...
 

Eldafint

New member
I don't know how to use the voltage injection method so I went ahead and removed the caps one by one until none remained, but there was still a short. Turns out there was a short on pin 1 of J9000. Too confident in my soldering skills to check there first. Oh well...

Anyhow the short is now gone and now all I have to do now is to find new caps. Thanks a lot for the help :)
 

Eldafint

New member
The soldering iron/station I'm borrowing is quite bad so it was far from a clean job. Board held up fine but can't say the same for all of the caps unfortunately.
 

2informaticos

Administrator
Staff member
Avoid this in the future; ad first 138 degrees solder paste on the pins.
Even better the QuikChip alloy, 58 degrees version.
 
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