[SOLVED] Green Artifacts on LCD - 820-2523 bad LVDS MUX U9600

[JorgePayar]

No Title

It seems to me like the lcd connector pins probably are unstuck. They are usually stuck with glue, I had the same problem with an 820 2530 2009 lcd screen.
I did this (see picture) and it works well but it is for me for a customer probably you´ll have to glue them again, anyway try first pressing the connector carefully with your finger if the green artifacts are gone doing that, and let us know.

 

[ClarkDV]

It seems to me like the lcd connector pins probably are unstuck. They usually are stuck with glue, I had the same problem with an 820 2530 2009 lcd screen.
I did this (see picture) and it works well but it is for me for a customer probably you´ll have to glue them again, anyway try fist pressing the connector carefully with your finger if the green artifacts are gone doing that, and let us know.

I have now tested this with 3 different LCDs and 3 different LVDS cables and the green artifacts are still there.

 

[larossmann]

Tap U9600 with your fingernail and tell me what happens.

 

[JorgePayar]

No Title

Tap U9600 with your fingernail and tell me what happens.

Tapping to locate a short by Louis Rossmann xD

 

[larossmann]

Cracked ball under the LVDS MUX is the most common cause when the machine gets over 5 years old on these models.

 

[ClarkDV]

Tap U9600 with your fingernail and tell me what happens.

That's it! When I tap U9600 the green artifacts come and go. If I apply slight pressure to U9600 the green goes away so long as I hold pressure on it.

That's a small chip, with lots of that adhesive rubber stuff around the edges, any chance of reflowing it or should I move on?

 

[aprendiz]

Remove all the glue and reflow.............

 

[larossmann]

Reflow is fine here, this is not a flip chip design, and it is not a chip that gets hot. It is an issue with the balls. Toss flux under and reflow like aprendiz said! Of course remove the edge bonding crap.

 

[ClarkDV]

I've never reflowed before and I'm terrified I'll screw something else up but I'm gonna give it a go!

Any pointers as far as temperature of hotair station and how much airflow? I've watched Louis's videos on doing this but would like some hear and air suggestions before I attempt it.

Thanks!

 

[larossmann]

Just practice on dead boards.

 

[dukefawks]

I've not had much success reflowing the GMUX. I always end up pulling it and reballing. If you thought the SMC was a bitch then U9600 is a whole new level.

 

[ClarkDV]

I've not had much success reflowing the GMUX. I always end up pulling it and reballing. If you thought the SMC was a bitch then U9600 is a whole new level.

Uh oh, Louis and others make it sound like a normal day at work for them to do it, but you say you've not been very successful doing it.

Makes me want to just put a shim on it and let the bottom cover keep pressure on it instead of risking a reflow and potentially ending up with a completely fried chip or some other part of the board stops working!

That's why I asked for heat and airflow settings. I could practice on a dead board but that won't tell me if I've done damage with the reflow, to the MUX chip or other nearby components.

 

[larossmann]

All of my reflows work. The problem is that you need a preheater or a very strong hot air station because the board has a high thermal mass in that area with the MCP being right under it. If you don't have a preheater just sit it in the oven at 290f for a half hour before you work on it, quickly transport it to your workbench, and reflow.

If it needs reballing, which is only when someone else destroyed it, I don't bother fixing it, it isn't worth the hassle.

Heat and airflow settings are a total waste. My JBC at 420c hits 530c and my weller at 1000f is lucky to do 400c. It won't translate to whatever you are doing. You just have to practice on a donor board.

Here you'll see a student reflow his first U9600 successfully. If Sean can do it, so can you! https://www.youtube.com/watch?v=n9FgTfj98TQ

 

[ClarkDV]

All of my reflows work. The problem is that you need a preheater or a very strong hot air station because the board has a high thermal mass in that area with the MCP being right under it. If you don't have a preheater just sit it in the oven at 290f for a half hour before you work on it, quickly transport it to your workbench, and reflow.

If it needs reballing, which is only when someone else destroyed it, I don't bother fixing it, it isn't worth the hassle.

Heat and airflow settings are a total waste. My JBC at 420c hits 530c and my weller at 1000f is lucky to do 400c. It won't translate to whatever you are doing. You just have to practice on a donor board.

Here you'll see a student reflow his first U9600 successfully. If Sean can do it, so can you! https://www.youtube.com/watch?v=n9FgTfj98TQ

I've studied that video several times as I prepare to do this. I also understand that different hot air stations will perform very differently.

What I'm looking for, I guess, is more of a general answer, do I set my station for high heat and low air, so as not to blow the tiny solder balls out, or do I go for both high heat AND high air?

It sounds like the idea is to get it hot, quickly, and get out, right?

 

[larossmann]

420c 75% air. quickly is a subjective term. the board must be warm to the point where it is not absorbing the heat you put on the chip.

heat the chip enough to get solder balls melted, not enough to fuck up the chip. if you can tap it and it moves a tiny bit you're good.

 

[ClarkDV]

OK, I'm gonna give it a try. Last question, I've never used my toaster oven to preheat a board, is it OK to sit the board on the rack or should I put something under it so the metal rack isn't touching the underside?

 

[larossmann]

metal rack touching it is fine, you are far away from a temperature that will melt solder or hurt anything

 

[ClarkDV]

How is best way to remove the edge bonding glue? Heat in the oven and peel it off or use hot air station?

 

[ClarkDV]

Never mind, should have tried a few things myself before asking. Hot air at around 300F and they come right up!