purple spots on JVC 30W585

[thabiz]

Hope somebody can help solve this problem. I got this tv 4 months ago and about a month ago weird purple spots started showing up at the bottom and sides of the screen. It only shows up on light colors like red and orange and is on all video sources(tv, dvd, etc.). Is there anything that could be causing this that isn't a tube problem. I have removed all speakers and electronics around the tv thinking it was interferance, but its still there. Its really driving me nuts!

Thanks

forgot to add that the spots fade in and out.

[Ratman]

Maybe this will provide insight?
http://www.hdtvoice.com/voice/showthread.php?t=14396

[KuipeDogg]

Dont know if this helps but I know "anything" metal around the tv can cause a magnetic field with large CRT's, but that shouldnt effect HD-ILA's,
Ive had the 30w585 for haf a year+ and neveer had any problems, but We at the store a dvd player under a 32" JVC and it made it green and purple couldy all over we couldnt figure it out for weeks and almost sent it back, same with a "magnetically shielded" sub that was too close (2 ft)

[thabiz]

found the problem.....it was the garbage shoot in my apartment which is against the wall that the tv was on. man are these things picky about where they get placed

[Ratman]

Are you kidding me?

I wouldn't expect LCoS to be affected by EMI.

It didn't happen for the first three months then just 'popped up'?
Static electricity in the chute perhaps?

Who knows? If it is, you could probably get someone to "ground" the chute to drain/discharge the static.

How did you come to surmise that it was the chute?
Have you come up with a solution?

[thabiz]

i had moved the tv about a month after i got it, and put in the corner of our livingroom. the chute is right on the other side of the wall. it drove me nuts thinking what it could be. removed everything(and i do mean everything)from around the tv and it was the same. A friend of mine one day just was kidding around and suggested it was the garbage chute. moved the tv and it went away. i guess it could be something else, but its the only metal object in that area.

[Ratman]

Strange!
Hey... whatever works! If you put the TV back, is the problem still present? Just curious...

[thabiz]

if i put the tv back it goes right back......and it was bad........about 3" on the bottom-middle and two big splotches on the sides......brutal!!!!

[Ratman]

Brutal? Perhaps...
Strange? You bet!

There's got to be something in that chute that is producing EMI.
I wonder if they are running any type of electrical wiring along the ductwork (chute)?

[KuipeDogg]

Brutal? Perhaps...
Strange? You bet!

There's got to be something in that chute that is producing EMI.
I wonder if they are running any type of electrical wiring along the ductwork (chute)?

***********
the EMI field is created by the TV and ANYTHING METAL, the metal object doesnt need to be charged just conductive and close enough, ive seen people who have metal studs in the walls and cant have a tv in their room, you shoulda seen how long it took to figure that one out.

If your real creative you could build a shield with aluminum

[Ratman]

Did you not read my post?

And... did you read my post?

I wouldn't expect LCoS to be affected by EMI.
It didn't happen for the first three months then just 'popped up'?

Have an explanation (without the condescension)?

[thabiz]

i had the tv in a diferent area for the first month and it was fine then moved it to the offending wall and bingo.....purple time! Have had it in a new spot for a week now and no signs yet

[Ratman]

If you really want the TV by the problem wall you could try to find a piece of steel (shelving?) and place behind the TV. Place it around the back between the yoke and the wall. Observe if there are any changes on the CRT. You have to slowly move it around.

If you find a 'sweet spot', you could possible attach it to the back of the TV or the wall.

Here's another (albeit expensive) option. But... some good info nonetheless:
http://www.mushield.com/faq.html

[thabiz]

thanks for the tip

[KuipeDogg]

And... did you read my post?



Have an explanation (without the condescension)?

The *Shelf* has to be aluminium, dont just use any metal, you can probably get paint special (and expensive) that would work

[Ratman]

Did you not read the FAQ?
Mild steel (1020) can shield magnetic fields and is appropriate for applications requiring a small attenuation of a high flux density field.

From another reference:
Here's how the permeabilities of some common materials compare:
Air ........... 1
Copper ...... 1
Aluminum ... 1
Tin ............. 1
Lead .......... 1


Nickel .................. 100
Commercial Iron ... 200
Stainless Steel ....... 200
MagnetShield ........ 4000


Magnetic Shielding Alloys* ....... 20,000+
Annealed MetGlas ................. 1,000,000

You can purchase materials to 'coat' that aluminum to increase the effectiveness.

[KuipeDogg]

Did you not read the FAQ?
From another reference:
You can purchase materials to 'coat' that aluminum to increase the effectiveness.


yeah...PAINT...its like paint thats what I just said dude,
and I dont consider info provided by companies trying to sell you their products as FAQ's

not offense... not trying to be condesending,

I had this same problem with customers of mine before and this is how we fixed it, I got my info from an electrical engineer

[Ratman]

Dude...
If you have steel shelving laying around or can 'obtain' from work, it makes it easy. Especially before someone makes an investment in the material(s).

The point is that aluminum is not the best/effective EMI 'blocker'.