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Component modding CRT TV - "China TV"
Zebidee:
--- Quote from: Razmann4k on July 19, 2025, 06:37:11 pm ---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.
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Oh dear, this is what I always dread. Fortunately it hasn't happened to me, or at least I've always been able to find a work-around.
--- Quote from: Razmann4k on July 19, 2025, 06:37:11 pm ---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!
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Don't assume anything, unless there is no other option! Many of the world's biggest problems are caused by people making false assumptions.
Requiring you to use a special service remote is especially cruel. I've heard of it before for things like PVMs, not China TVs though! Let's hope it isn't that.
Have you tried to use your normal remote? Maybe that is all you need. Does it have a "M" key? Maybe M just means "MENU".
Some remotes have a secret service mode button: they might have a small hole by which you can use an unfolded paper clip or something to press the service mode button. Much like ejecting a sim from a smart phone. Sometimes they have a button that is only accessible by pulling the remote apart.
Otherwise, you might need to directly hack the EEPROM. You only need to change one byte from "0" to "1". This will be purely educated guesswork. You might be able to guess which byte by comparing nearby values with the defaults stated in that datasheet.
Looks like you have a 24C08 EEPROM (8K, 1024x8, 64pages x 16 bytes), but I can't be sure as your picture does not provide enough detail. I've circled in yellow what I believe to be your EEPROM. You should also look around for an unused 4-pin header, sometimes they are already on the PCB, but unpopulated. I see an unused header that looks promising, circled in turquoise.
Sometimes, like with my recent mod to a TCL CRT TV, I was somehow prevented from editing the EEPROM while it was on the PCB via a read-only setting. I don't understand exactly how or why they achieved this for my TCL TV, maybe something to do with the jungle IC. If yours is similarly "fixed" to read-only, then you may have to physically remove (de-solder) the 24C08 from the PCB to edit it. You could also try copying the .bin file onto a fresh new IC, which hopefully won't have the read-only settings.
Anyway, before editing anything you should extract a backup. You would also probably find it worthwhile to order some 24C08 ICs while you are ordering the CH341a EEPROM editor/reader. Both are cheap and available from your favourite online retailers.
For more on EEPROM hacking, please have a look at my recent thread on this.
You could also try searching for other examples. I did a search on "eeprom buttersoft markozlad" and got many interesting hits. I chose those two users specifically because I know they have explored TV EEPROM hacking to enable RGB mode on the Aussiearcade.com and shmups.system11.org forums.
Looking at your input mini-PCB, at first I thought you had gotten the inline capacitors and resistors back-to-front, and you used 75R instead of 100R, but I see that is how they are in the schematic you provided. I'd probably just stick to ceramic capacitors where possible, though the blue polypropylene film caps you've used should be sufficient. If it works then it works :D
Hope that helps.
Razmann4k:
Well, I've got great news! I followed your advice and took the remote apart, after a few minutes of prodding around different traces, I found the factory mode button! I managed to enable YUV, and I now have component! I also made a v2 of the input mini-PCB with 103 caps instead of the blue ones and shielded wire this time. I wish I had a picture of it but I already closed up the TV because I was glad I could finally get it over with. :lol
The factory menu on this TV has about 20 pages of settings, very thorough, and strangely enough you can enable YUV but right underneath you can enable DVD, which I though was the same thing, and even the TV doesn't seem to know the difference! When I enabled YUV and DVD, the component input showed up under the DVD input, and when I disabled DVD, then it showed up under YUV-in. The only downside to all of this is no matter what I do, this TV no longer shows colours with composite after I enabled YUV and DVD in the factory menu, even when I plug the composite input into the original AV in, which is very strange as I didn't touch any of that. I don't really mind as I don't ever plan on using composite again, but it's quite strange nonetheless.
Thanks again Zebidee!
Zebidee:
--- Quote from: Razmann4k on July 22, 2025, 06:14:37 am ---Well, I've got great news! I followed your advice and took the remote apart, after a few minutes of prodding around different traces, I found the factory mode button! I managed to enable YUV, and I now have component!
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That really is great news! :applaud:
--- Quote ---I also made a v2 of the input mini-PCB with 103 caps instead of the blue ones and shielded wire this time. I wish I had a picture of it but I already closed up the TV because I was glad I could finally get it over with. :lol
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I notice on the very last page of the service manual, there is a simplified schematic, focused on the jungle chip, with 104 caps on the Cr/Cb inputs.
Next time you open up the TV you might try experimenting by adding extra 104 caps in parallel with the 103's, which simply means lightly soldering the 104 legs over the existing 103 legs. This adds their capacitance, gives you 0.11uF, effectively the same as 104 by itself (0.1uF). See if it improves the picture or not. You won't break anything doing this, and the 104 caps are easy to remove if you don't like it.
--- Quote ---The factory menu on this TV has about 20 pages of settings, very thorough, and strangely enough you can enable YUV but right underneath you can enable DVD, which I though was the same thing, and even the TV doesn't seem to know the difference! When I enabled YUV and DVD, the component input showed up under the DVD input, and when I disabled DVD, then it showed up under YUV-in. The only downside to all of this is no matter what I do, this TV no longer shows colours with composite after I enabled YUV and DVD in the factory menu, even when I plug the composite input into the original AV in, which is very strange as I didn't touch any of that. I don't really mind as I don't ever plan on using composite again, but it's quite strange nonetheless.
Thanks again Zebidee!
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Cheers! :cheers:
Try setting various things back to default, especially relevant parts of menu page 3. But for all I know it might be something else, like in the colour system settings.
Razmann4k:
As for the 104 caps, will do! I forgot that that the pdf would contain the defaults, thanks for mentioning that, I'll confim all the settings apart from YUV is set to default (in that menu, not the specific tuned settings for my tube of course!)
At the moment believe it or not but I don't have a decent way to even test my component. I've been using a DVD player but the Cb port on it seems to be dead (confirmed with modern TV). Another old DVD player I have works properly when I plug it into my modern TV via component but when plugged into the CRT it's a garbled scrolling mess, which I've deduced as it outputting 480p instead of 480i. Now the DVD player can output 480i but I don't have a remote to change the settings with! Until my PS2/PS3 component cable shows up, I just have to hope it works properly because the Y and Cr looked good on that other DVD player.
Zebidee:
--- Quote from: Razmann4k on July 22, 2025, 09:33:01 am ---As for the 104 caps, will do! I forgot that that the pdf would contain the defaults, thanks for mentioning that, I'll confim all the settings apart from YUV is set to default (in that menu, not the specific tuned settings for my tube of course!)
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Yeah - I also forgot to suggest trying a 104 (0.1uF, instead of the 1uF can cap) on Y - though it is a little more hassle to test as you'd have to remove the 1uF. On my TVs I found that the default 1uF cap made Y a tiny bit fuzzier, less sharp - though some might see this as an advantage!
This is because these jungles artificially create a slight delay on the chroma signals as it takes a few hundred nanoseconds (fraction of a microsecond) for the IC (basically a tiny computer) to digitally process or "demodulate" the analog Pr/Pb into Cr/Cb and then => RGB, the delay means a visible Y/luma shadow, to the right, can be visible in some situations with a crisp 240p input. So, making the Y a little fuzzier disguises the delay. So I suggest trying 104 (0.1uF) on Y, but ultimately you may prefer the 1uF.
Anyway, probably best to wait until your PS2/3 component cables come in to test that.
--- Quote ---At the moment believe it or not but I don't have a decent way to even test my component. I've been using a DVD player but the Cb port on it seems to be dead (confirmed with modern TV). Another old DVD player I have works properly when I plug it into my modern TV via component but when plugged into the CRT it's a garbled scrolling mess, which I've deduced as it outputting 480p instead of 480i. Now the DVD player can output 480i but I don't have a remote to change the settings with! Until my PS2/PS3 component cable shows up, I just have to hope it works properly because the Y and Cr looked good on that other DVD player.
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Try swapping the red and blue component cables - the colours will be wrong, but at least you can test if the Cb channel on your jungle IC is working properly. If it isn't then your jungle might have a dead channel. This happened to me with my TCL TV mod - I replaced the jungle! Also prompted me to start including 12v zener diodes for input protection.