Chinese Assembled Analogue IO/Component Video Color Issues
Posted: Wed Jan 05, 2022 3:18 pm
I'm new to Mister and wanted to relay some of the experience I've had regarding issues with component video. Like some others, my IO board came pre-assembled from China and I was immediately dissapointed with the component video output. It appeared to have a slight magenta hue that I wasn't able to properly correct for using my CRT's service menu (Toshiba 27A43). As far as I could tell (tested with one VGA lcd monitor), VGA appeared normal.
I tried different .ini settings but was able to verify that mine were correct. I re-flowed most points on the board with no change in the issue. After searching through many different forums, I came to the conclusion that it was most likely the resistor array combination. My board was using a 201/471 combination, which was wrong because the second resistor set should be as close to 2 times the first as possible. I read that some UK boards were using a 240/470 combination that appeared to work correctly so this is what I intended to aim for. I also found that 300/604 was popular.
I went ahead and ordered some 240's/300's/604's from Mouser just to have enough to try all of them. First, I simply replaced the existing 201's to create the combo 240/471 (from what I heard, the 471's are still 470 ohm). Maybe one of my joints was bad, or maybe there were issues with the 471's, but this combo did not provide a desireable effect. The magenta hue was gone (yay!), but in return, I got missing colors and some other distortion.
Next, I tried the 300/604 combo and this was the winner. The colors were accurate and no percievable distortion. However, it comes with it's own downside, the RGB output was noticeably weaker which I was easily able to correct with some contrast/brightness adjustments on my TV.
Sorry any technical errors that may be in this, I just wanted to piece this together for anyone else that may be experiencing this and not know how to proceed.
Moral of the story, if you buy one of the cheaply built IO boards and are getting color issues, check the resistor combination and if it's 201/471, you might want to look at getting a refund if you don't have the equipment to replace the resistor arrays.
I tried different .ini settings but was able to verify that mine were correct. I re-flowed most points on the board with no change in the issue. After searching through many different forums, I came to the conclusion that it was most likely the resistor array combination. My board was using a 201/471 combination, which was wrong because the second resistor set should be as close to 2 times the first as possible. I read that some UK boards were using a 240/470 combination that appeared to work correctly so this is what I intended to aim for. I also found that 300/604 was popular.
I went ahead and ordered some 240's/300's/604's from Mouser just to have enough to try all of them. First, I simply replaced the existing 201's to create the combo 240/471 (from what I heard, the 471's are still 470 ohm). Maybe one of my joints was bad, or maybe there were issues with the 471's, but this combo did not provide a desireable effect. The magenta hue was gone (yay!), but in return, I got missing colors and some other distortion.
Next, I tried the 300/604 combo and this was the winner. The colors were accurate and no percievable distortion. However, it comes with it's own downside, the RGB output was noticeably weaker which I was easily able to correct with some contrast/brightness adjustments on my TV.
Sorry any technical errors that may be in this, I just wanted to piece this together for anyone else that may be experiencing this and not know how to proceed.
Moral of the story, if you buy one of the cheaply built IO boards and are getting color issues, check the resistor combination and if it's 201/471, you might want to look at getting a refund if you don't have the equipment to replace the resistor arrays.