luma is gone

[lnx64]

Oh shit, I hope i can fix this till the new walking dead starts!

My samsung in my sig just lost all luma.. I can see the chroma on the screen, like a dark oversaturated mess, but the luma is not present..

Where should I even start?

[lnx64]

Well, I'm getting to watch the show rather uniquely tonight, haha. No answers, but that's ok, was kinda a rush and I can't expect a rushed response.

[dieseljeep]

Originally Posted by lnx64

Oh shit, I hope i can fix this till the new walking dead starts!

My samsung in my sig just lost all luma.. I can see the chroma on the screen, like a dark oversaturated mess, but the luma is not present..

Where should I even start?

Take the back off again. Tap gentiy around on the PC board.
Was there any forewarning, such as the luma being intermittant?
Sounds like a fun one.

[old_coot88]

Gently rap the neck of the CRT and see if the luma flickers in and out. An H-K short in the jug can kill the luma, leaving chroma unaffected, since chroma goes in on the grids. Also a dirty service switch (if the set has one) can kill luma.

[old_coot88]

OOPs! Double post

[dieseljeep]

Originally Posted by old_coot88

Gently rap the neck of the CRT and see if the luma flickers in and out. An H-K short in the jug can kill the luma, leaving chroma unaffected, since chroma goes in on the grids. Also a dirty service switch (if the set has one) can kill luma.

I was thinking that myself, when I replied.
IIRC, the original poster was saying that the CRT is running on borrowed time.

[lnx64]

Yea, the CRT is in fact on borrowed time, it's getting old. But the previous night it was nice and bright. I turned it on today, and it's looking like this.

I gently tapped the CRT, nothing.. Checked around the mainboard, and checked it's service switch. Sure enough, just touching the switch got luma flicking back to life again.

I'll need to either replace that switch or clean it somehow.

[compucat]

Originally Posted by lnx64

Yea, the CRT is in fact on borrowed time, it's getting old. But the previous night it was nice and bright. I turned it on today, and it's looking like this.

I gently tapped the CRT, nothing.. Checked around the mainboard, and checked it's service switch. Sure enough, just touching the switch got luma flicking back to life again.

I'll need to either replace that switch or clean it somehow.

Just spray the service switch with Deoxit and work it a few times. It should be fine after that.