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Component modding CRT TV - "China TV"
Zebidee:
--- Quote from: dennisbgi7 on May 09, 2025, 03:46:15 pm ---Firstly, amazing idea and amazing execution, this is fantastic. I did have a question, more of a noob question since I am new to all this.....what did you do about the audio? I understand the side port now takes in component video signals, but since the composite audio is being replaced in this case, what are you doing about that? Also, is the composite input at the back still usable after this?
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Thanks.
Composite video and audio L/R can be input to a standard set of 3 RCA ports at the back: yellow for video and red/white for audio. They still work as normal.
Both component and composite video can be connected at the same time, and I can flick between inputs with the remote or the front menu buttons. However, both composite and component share the same audio inputs.
See this pic of the rear inputs, and the unpopulated component input holes. Designed to share the same audio inputs as composite, and in these TVs is all connected together internally. I didn't use those blank holes as there was no convenient way to securely mount the extra ports inside. Re-purposing the side connector was much neater and easier.
dennisbgi7:
Thank you so much for the response. I am actually using this as a guide and planning to do this myself soon. However, since I am a newbie, I do still have some questions, primary of which is that, in the first post at the end you mentioned having to add the ground wire by modifying the pcb...what modification did you have to do on that one?
Zebidee:
--- Quote from: dennisbgi7 on May 10, 2025, 04:24:57 pm ---... in the first post at the end you mentioned having to add the ground wire by modifying the pcb...what modification did you have to do on that one?
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Ah, you mean the side connector?
Unfortunately I didn't take any pics of the modded back side, and I've reassembled all the TVs now.
Every TV model be a little different, and I've done about 5-6 TVs now. They all required some modification, but slightly different in each case. In most cases the left/right audio channels (red/white) were connected at the PCB. In most I had to use a craft knife to carefully cut a channel separating the audio inputs - sometimes a small cut, sometimes quite large. In all cases the cables back to chassis had only 3 wires (video, audio, ground), but for our purposes we need 4 wires (Y, Pb, Pr, ground) so a wire must be added.
Here are some pics of a side connector I salvaged from a dead TV. The TV had been left out in rain by a former owner, thus the corrosion on the outer metal shell.
Those coloured insets (yellow/red/white) can be removed and replaced with something else - you will need to desolder the metal ground shells from the PCB and prise them off with a small screwdriver or something. Then the coloured "donuts" come out, you can replace them with something more appropriate. I happen to have RGB coloured ones handy already, but you could make them yourself from some plastic or card.
Here is a close up of the underside. The three big pins at top, all connected together, are the grounds. They all connect to the metal shells on the other side. You'll need to desolder them to change the coloured insets.
The three big pins below that are (from left) for video, audioL and audioR. Notice that audioL & audioR lines are linked by a small bit of trace? I marked this in yellow.
The three smaller pins at top left are where the cable connects. See how only one audio wire is connected? Forget about stereo sound with this TV! The other two are for video and ground. There is a spot to add a fourth wire, but it isn't used. I marked this in turquoise, this is where you'd add the extra wire when modding this for component input.
So this side connector would be very easy to adapt for Y Pb Pr. You could just cut the small bit of connecting trace between the audio L&R. In this case the ground is already connected, would need to add a wire for one of the component colours.
dennisbgi7:
Thank you very much! That cleared it up completely. Now I feel confident enough to attempt the modding.
Razmann4k:
Hi Zebidee, thanks for this guide, it's really in-depth and helped me out a ton ;D. I'm in a bit of a pinch however, as I completed the component mod on my TV but cannot get the factory menu open to enable YUV. My TV is branded as a 'Sonistar T-1499', and it uses the LA76931 jungle chip. I found a factory manual for the chip, which I will attach below. The factory mode information is on pages 57 - 62 and the gist is: 'Press “M” key to enter into factory mode, “M” will show on the top left corner of screen.' and ' You need a repair RC(model: HYDFSR-N-GEO)'
I'm assuming that means it's not possible to bring up the factory menu with the normal TV remote, have you ever run into this before? I tried looking up this HYDFSR-N-GEO service remote, but I can't find anything helpful. I just don't want my work on the component mod to waste :-\, so if you know anything I can do, that would be great!
Thanks.