RF Ghosting

[lnx64]

So we had a lovely power surge last night due to someone crashing into the power poll on our street (I don't know if they are ok but I do hope they are alright).

Most of our electronics are ok, but something weird happened with my bedroom TV. The colors went way out of whack, very green tint. So I adjusted it last night. And today it was very purple. So I adjusted it again. Now I noticed that the RF tuner section appears to have ghosting which didn't used to be there.

Any idea's on where I should look?

https://i.imgur.com/zzxs9Yj.png

It's a Samsung C9110M A according to the sticker inside the set.

EDIT: Now it's going green again. I don't get what happened to this set.

[old_tv_nut]

CRT TV, yes?
What is the signal source? Can you try another source to feed this set, and try another set to view this source? With multiple problems it is possible for multiple devices to be at issue.

[lnx64]

Originally Posted by old_tv_nut

CRT TV, yes?
What is the signal source? Can you try another source to feed this set, and try another set to view this source? With multiple problems it is possible for multiple devices to be at issue.

That's what I'm suspecting right now. CRT, mid 80's.

I have tried another source, including my Sencore, and there's some oddities.

On the Sencore, if Chroma is enabled, the picture has a greenish blue tint. If I kill chroma and only send Y, the picture becomes reddish. It almost appears that the color issue is on the NTSC decoding side of things, and the ghosting is on the RF side (multiple sources show the same issue with the ghosting).

[old_tv_nut]

Rather than RF, I'd guess that ghost is likely in the video section (or maybe IF/detector) - perhaps some component has lost its ground connection or is burned out.

Summary: seems like multiple failures - good luck.

[Electronic M]

Adjust and check grayscale with the TVs color decoder off. Tint shifts could be caused by ghosting and the grayscale changes you see with color turned on/up could be the color decoder passing erroneous DC voltages to the CRT.

[lnx64]

Ok I think I might be done here. My girlfriend was here and she kept insisting it's not going green, it's going "turquoise". So with chroma turned off, it still shifted again. With her saying I'm wrong and it's not going green but turquoise I think to myself that would maybe mean RED is actually going down rather than green going up.

She was right. As soon as I touched the red drive control it flickered like mad. So I shot it with some deoxit and now it looks like I might be obtaining a stable picture now. Still not sure how a power surge caused the pot to go whacky, unless it was just a coincidence.

As for the ghosting, I decided to inject IF straight into the board since there was mention of RF, looking to chase the path of the signal. Luckily my blonder tongue's IF frequency is the same as this TV's so I unhooked the tuner entirely and connected the IF out of my blonder tongue agile modulator straight into the set, and now the picture has zero ghosting.

Here's a picture of it in operation now: https://i.imgur.com/nTcNGbU.jpg

So now I've come to the conclusion that for the ghosting one of two things may have happened. Either the RF modulator I am using (not the blonder tongue but a cheap Radio Shack one) failed, or during the surge it damaged the tuner itself. I'm going to go with the grounding recommendation that was mentioned here, as it honestly seems like RF reflection. I'll be checking everything later. For now the IF injection looks actually better than even before all this happened so I might even consider just keeping it this way, looks almost like composite video directly being fed in.

[zeno]

If it has a coax input there will be a silver box for isolation between
the RF in and tuner. Be sure its not burned inside from the surge.
Used to be real common from lightning hits.

73 Zeno
LFOD !

[lnx64]

Originally Posted by zeno

If it has a coax input there will be a silver box for isolation between
the RF in and tuner. Be sure its not burned inside from the surge.
Used to be real common from lightning hits.

73 Zeno
LFOD !

Hmm, I didn't see one. It does have a multi input with coax and 300 ohm twinleads, and there's a ceramic cap across the 300 ohm terminal. I wasn't using the 300 ohm input, but I tried swapping the capacitor out anyway, and when I removed the cap the ghosting on the RF input went away entirely. Despite not using that input, it appears it is somehow connected to the same circuit (I'm not entirely sure then what the 300/75 switch does if it's still in circuit).

I'm debating soldering in a new capacitor or just leaving it out since I don't use twin leads on VHF anyway.

[Dude111]

I hope she is happy again and working good

[lnx64]

Yep, I watched all 3 Matrix movies last night on it, and it didn't have really any issues. It did look like the brightness fluctuated a little in some spots but that might have been the AC kicking on, it's always been sensitive to that.

[Dude111]

Excellent im glad