SONY CRT No Video, Only Audio

Thread Starter

mcasten86

Joined Jun 13, 2020
7
Hello,
I recently came across a SONY Trinitron KV27FS12.
Upon testing with a N64 composite cable to the front (VIDEO 2) I witness audio working perfectly but the picture is black. On the rear I plugged into VIDEO 1 and VIDEO 3 and the same occurred. (This N64 works perfectly on other CRT TVs/Monitors)
I also did a test with a Playstation 2 and also a Nintendo Wii to the same results.

When plugging the composite cables into VIDEO 4 (which has the component cable colors) it shows a black and white picture. The TV's menu has colors and looks crisp and clear and appears on all video channels.

If you any any suggestions I'd greatly appreciate the help. I imagine the cuprit is internal but not sure where to look.
(images are of VIDEO 4 with black and white N64 via composite and the TV's menu. VIDEO 1, 2 and 3 are black so no real point to attach photos but there's one of VIDEO 2.)
 

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Ramussons

Joined May 3, 2013
828
Composite video does not carry audio. It has only Syns, Luminance and Colour.
Audio is a seperate connector.
Can we have pictures of the Input connectors - the full lot.
 

Thread Starter

mcasten86

Joined Jun 13, 2020
7
Composite video does not carry audio. It has only Syns, Luminance and Colour.
Audio is a seperate connector.
Can we have pictures of the Input connectors - the full lot.
Sorry, I made a mistake with how described that post. It's just an AV cable. Here are the photos of the front for Video 2 and the back.
 

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abrsvc

Joined Jun 16, 2018
37
The video input section has a problem. I don't have the service manual with me at the moment, but this should be a simple repair. If the TV works with the component inputs, I would look at the composite video processing section. This is a single IC if I recall correctly. I will look this up tomorrow when I return to the shop and update.

I would start looking for poor solder connections as these inputs rarely fail. Start with the simple things and repair connections that appear to have rings. This is a start.
 

Thread Starter

mcasten86

Joined Jun 13, 2020
7
The video input section has a problem. I don't have the service manual with me at the moment, but this should be a simple repair. If the TV works with the component inputs, I would look at the composite video processing section. This is a single IC if I recall correctly. I will look this up tomorrow when I return to the shop and update.

I would start looking for poor solder connections as these inputs rarely fail. Start with the simple things and repair connections that appear to have rings. This is a start.
Thank you for your response. I have uploaded a service manual on wetransfer.com: https://we.tl/t-d1ACanD9gE
I will inspect internally later today.
 

Thread Starter

mcasten86

Joined Jun 13, 2020
7
The video input section has a problem. I don't have the service manual with me at the moment, but this should be a simple repair. If the TV works with the component inputs, I would look at the composite video processing section. This is a single IC if I recall correctly. I will look this up tomorrow when I return to the shop and update.

I would start looking for poor solder connections as these inputs rarely fail. Start with the simple things and repair connections that appear to have rings. This is a start.
Here are some images of the boards. I'm not noticing anything off, everything looks very clean and new but I will keep going over it one by one.
 

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Thread Starter

mcasten86

Joined Jun 13, 2020
7
Wanted to post a quick update.
Tested the CRT with component cables and video and audio works perfectly fine.
Also did a test with S-Video and it has the same results as composite. Still unsure what the solution would be. Any help would be immensely appreciated as some of my consoles can only work via composite/s-video
 

Zeeus

Joined Apr 17, 2019
597
Wanted to post a quick update.
Tested the CRT with component cables and video and audio works perfectly fine.
Also did a test with S-Video and it has the same results as composite. Still unsure what the solution would be. Any help would be immensely appreciated as some of my consoles can only work via composite/s-video
which of the boards in your post is for the video connectors?
Have you checked for shorted ceramic caps, bad diodes?
 

Thread Starter

mcasten86

Joined Jun 13, 2020
7
which of the boards in your post is for the video connectors?
Have you checked for shorted ceramic caps, bad diodes?
I think I actually posted the wrong boards. The board that the video connectors are attached to is a smaller board that doesn't slide out like the S-board.
I'll check the cermaic caps and diodes. I'm a little new to all this so your suggestion is a huge help. I have somewhere to at least look at now where as before I just didn't know where to start
 
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