42" Maxent Plasma MX-42XM11 Lines on screen

[tom66]

Re: 42" Maxent Plasma MX-42XM11 Lines on screen

What are the specs for the zener? I can't seem to figure out the code marking

Whatever is originally marked on the zener. Leave it as is - replace the original part. It's part of the power supply. If that zener goes wrong, a fuse blows or the PSU doesn't work at all.

It *won't* cause digital noise.

[tieny]

Re: 42" Maxent Plasma MX-42XM11 Lines on screen

Well, I'm stuck. I don't know what exactly i'm looking for. I tried cooling the entire main board to see if it would effect the problem. But even while cooled the rate of lines appearing didn't change.

I included photos of the main board back and front.

[tom66]

Re: 42" Maxent Plasma MX-42XM11 Lines on screen

Have you tried pressing on the main processor, the one with the green heatsink?

[tieny]

Re: 42" Maxent Plasma MX-42XM11 Lines on screen

Hm it seems pressing down on the main processor causes more lines to appear, and releasing the pressure causes the new lines to disappear. Actually this is true for any of the chips I press on

Leaving the tv off doesn't take away the problem anymore. Now the lines appear the moment I turn it on.

[tom66]

Re: 42" Maxent Plasma MX-42XM11 Lines on screen

Hm it seems pressing down on the main processor causes more lines to appear, and releasing the pressure causes the new lines to disappear. Actually this is true for any of the chips I press on

Leaving the tv off doesn't take away the problem anymore. Now the lines appear the moment I turn it on.

This would definitely point to a cold solder joint somewhere; try and localise it by pressing on other chips. Such as the ones without any leads on the outside; the EtronTech one is a good possibility (this is probably RAM.) Do you have a part # for the board? It may be available cheap.

[tieny]

Re: 42" Maxent Plasma MX-42XM11 Lines on screen

The part # is QPWB11526-1G -1-

The lines are becoming more stabilized so there's less change when pressing down on the chips. At one point I noticed that when pressing down on IC12 (next to the analog input in photo 2) some lines disappeared. It is the only chip that manage to decrease the amount of lines when pressed down. There might be more chips but it's under the metal cover over the inputs which is soldered on the board.

[tom66]

Re: 42" Maxent Plasma MX-42XM11 Lines on screen

I see it's $100 on eBay - so most likely not worth it.

Do you have a part # for IC12?

[tieny]

Re: 42" Maxent Plasma MX-42XM11 Lines on screen

232cb p0509bhn7

[tom66]

Re: 42" Maxent Plasma MX-42XM11 Lines on screen

232cb p0509bhn7

That's a serial interface controller... especially if it's got 14 or 16 pins.

Unlikely to be the problem, but possibly in that local area.

Remember all the stuff near the inputs is likely for dealing -with- the inputs. Whereas the OSD is processed on the main processor using the RAM. You may be flexing the board causing the symptoms to go away in a different part.

[tieny]

Re: 42" Maxent Plasma MX-42XM11 Lines on screen

Alright i found the problem, it is the EtronTech RAM Chip. Pushing down on it hard enough or at a certain spot causes all the lines to disappear. (With the label "Etrontech" facing forward, pushing the right edge of the chip causes the problem to go away.) I just didn't press down on it enough being afraid I might damage something before.

How would I go about fixing this? ( I'm not familiar with these types of chips, are they soldered on?)

[tom66]

Re: 42" Maxent Plasma MX-42XM11 Lines on screen

Alright i found the problem, it is the EtronTech RAM Chip. Pushing down on it hard enough or at a certain spot causes all the lines to disappear. (With the label "Etrontech" facing forward, pushing the right edge of the chip causes the problem to go away.) I just didn't press down on it enough being afraid I might damage something before.

How would I go about fixing this? ( I'm not familiar with these types of chips, are they soldered on?)

As I expected - the only BGA device on the board it looks like.

BGA (ball grid array) devices have many tiny balls of solder underneath the device which can break with temperature and vibration causing the problems mentioned. Lead free solder is a prime reason for early failure.

There are several techniques to fix the problem - one is reflow and the other is reballing.

I would recommend reflow, but it usually only lasts for a short while. Reflow involves baking the board at around 230°C for 2.5 minutes. The idea is the solder will melt and the chip will be re-soldered.

You can sometimes also do reflow with a hot air gun.

Reballing requires you to remove the chip and replace every single ball, then resolder it. It's not for novices, but it's the only guaranteed way to fix it, sadly.

[tieny]

Re: 42" Maxent Plasma MX-42XM11 Lines on screen

I was afraid of this, guess I'll have to go and get myself a hot air gun. What type should i get (what temperature)?and What's the proper technique for reflowing this type of chip with a hot air gun?

[tom66]

Re: 42" Maxent Plasma MX-42XM11 Lines on screen

I was afraid of this, guess I'll have to go and get myself a hot air gun. What type should i get (what temperature)?and What's the proper technique for reflowing this type of chip with a hot air gun?

300°C will do. Look up the videos on the net on how to repair Xbox 360s and PS3s. Even then, the repair is usually fairly temporary.

[Jonny Accelerant]

Re: 42" Maxent Plasma MX-42XM11 Lines on screen

I'd be interested in a follow-up. Did reflowing the component fix the problem? If not, what was the problem?