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Component modding CRT TV - "China TV"
Razmann4k:
Actually I did exactly that, the screen was pink with only Y and Pr working, when I plugged Pb into Pr of the DVD player it was blue on the TV so I'm sure Pb on the Jungle is working fine! I'm quite looking forward to how this will look in games, the last time I laid eyes on a CRT was when I was around maybe 10, and that was RF/Composite at best! I'm sure a small 14 inch with Component and 240p/480i will make for a good combo! Naturally, the scanlines at 240p will be hard to spot at this screen size.
I hope my arcade joystick works on Retroarch on PS3, I guess we'll see :lol
Razmann4k:
So my PS2/3 TEMU component cables arrived, obviously not of great quality as they costed around $3USD. So I opened them and removed the connector and soldered it onto an unused official Xbox 360 set of component cables, which resulted in a much, much better image with almost no visible noise (I assume the tiny amount of noise I can see in dark scenes is coming from inside the TV itself. Anyway, the picture was actually too green, but after swapping the 103s with 104s that was also solved.
Now that I could finally display a png of a grid from the 240p test suite, I was able to properly calibrate the TV, adjust the V Size, V Pos and H Pos from within the factory menu (and the H Size, but that had to be adjusted with a pot on the board as it wasn't present in the factory menu). I noticed a problem however, when the image was dark the right side of the screen would shrink, so the image no longer stretched to the bezel, and bright scenes had the opposite effect.
Upon researching this I realised it was a quirk of CRTs (at least cheap ones). However, it is pretty bad, and I think adjusting the H Size to fit the entire image in the frame made it more noticable. Turning the contrast way down does help solve the problem and the geometry does improve, but I just don't want to have such a washed out image even if it means better geometry. I did a visual inspection of all the caps on the board and none of them seem to be bulging or aged, despite the TV being almost 20 years old now.
I was wondering what your opinion on this was, and whether I should bother trying to improve it?
Zebidee:
--- Quote from: Razmann4k on July 29, 2025, 11:57:57 am ---I noticed a problem however, when the image was dark the right side of the screen would shrink, so the image no longer stretched to the bezel, and bright scenes had the opposite effect.
Upon researching this I realised it was a quirk of CRTs (at least cheap ones). However, it is pretty bad, and I think adjusting the H Size to fit the entire image in the frame made it more noticable. Turning the contrast way down does help solve the problem and the geometry does improve, but I just don't want to have such a washed out image even if it means better geometry. I did a visual inspection of all the caps on the board and none of them seem to be bulging or aged, despite the TV being almost 20 years old now.
I was wondering what your opinion on this was, and whether I should bother trying to improve it?
--- End quote ---
This picture brightness and size variation is called "blooming", and it is a symptom of poor quality or failing power supply regulation. All CRTs have it to some degree, but mostly you don't notice it until it gets bad.
You can check all the capacitors. Some electrolytic caps blow up or leak dramatically, spraying or spewing junk, some just quietly fail without any obvious outward signs.
Buy and use an ESR meter to check on electrolytic cap health, especially around the power supply and the horizontal output stages (near flyback, HOT, yoke pins). While you are there, also visually inspect other components including the high-voltage "disc" caps for any signs damage. Carefully inspect the PCB board itself for any signs of damage or corrosion.
You could try bumping that 1uF cap on Y down to a 104 (0.1uF), though I don't expect this to do much about blooming.
Do you just accept the blooming and move on? That depends on you. Here is a story:
I once tried to reduce bad blooming, on a "brand-new" cloned Wei-Ya RGB chassis (from China). After replacing all the caps, and some other things, saw no improvement no-matter-what I did. Even cheap TVs had less blooming. I decided I was wasting my efforts on "polishing a turd", so instead chose to component-mod TVs and invent GreenAntz RGB-component transcoders! The final quality was much better and here we are.
Take from that what you will. I'd expect better from even a cheap TV. Buy an ESR meter. Check the power supply.
Razmann4k:
Thanks, will do! And I'm glad you got into component modding TVs because without this guide I wouldn't have one myself!
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