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Thread: New RGB to Component converter design using the BA7230LS

  1. #151
    Co-Creator of the MegaAmp Raging in the Streets villahed94's Avatar
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    I tested the circuit on several LCD TVs too (Samsung and Sony), and they present the greening at different degrees.
    Something curious though, is that one of my Samsungs actually rendered the picture as proper 240p or in terms of that TV:
    720x240 @ 60Hz.

    I think it's blue that's causing the issues, because Red gives out the proper colours and white when using just Pr is still white. However when using just Pb, the picture becomes yellowish, incluiding white. Any ideas?


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  2. #152
    Creator of the Mega Amp Raging in the Streets Ace's Avatar
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    Quote Originally Posted by villahed94 View Post
    So which TV were you using for the Daytona USA Saturn pic? It seems to be a CRT.
    The TV in question is an Electrohome 27E510 CRT TV from 2007.

    If you say you get excess green when Pb/B-Y is plugged in, you may need to add a resistor to B-Y. If you have a POT, solder it in and tell me what you get when you adjust it.
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  3. #153
    Co-Creator of the MegaAmp Raging in the Streets villahed94's Avatar
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    I just got home and I'm going to test with several values:
    100 ohm, 1k, 5k and 10k.


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    This's why I hate component video, the colour balance always seems to get thrown off.

  5. #155
    Co-Creator of the MegaAmp Raging in the Streets villahed94's Avatar
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    With Luma at 0 ohms(bypassing the 75 ohm one) the greening gets reduced A LOT.
    As a Side note I used the 2SC1741 as the transistor, I don't think that's the cause.

    Also is the greening a general problem or there are some BA7230s that don't have this issue?


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  6. #156
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    Since I had the same problem with the BA6592F (including the one in my SHVC-CPU-01 Super NES, but to a considerably lesser extent), I assume it is a generalized problem with ROHM encoders and Component video. I think they were really meant to just be used as RGB to S-Video and Composite encoders, not RGB to Component, but that may not necessarily be the case.
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  7. #157
    The medium-sized mang. Raging in the Streets Lastcallhall's Avatar
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    Just consolized a MVS 2 slot this afternoon and I used pots for ALL of my resistors. With some tweaking it looks very nice on my RPTV.

    That's 2/2 using pots - I may just go this way from here on out on all my consoles.

  8. #158
    Co-Creator of the MegaAmp Raging in the Streets villahed94's Avatar
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    Lasthallcall, could you please describe the tweaks you made to the circuit? It would be really helpful.


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    I built 9 of these circuits I followed the schematic ace posted to the key with all components and the colors came out fine, the only problem I ran into was that I found out that the circuit would only show up on my crt displays and not lcd which then I read that lastcallhall had used a potentiometer on the sync line to fix the problem, and well yes it works perfectly now I did notice that every display has a slight diffrence on how they handle the sync its strange 3 diffrent lcd tvs neded adjustment of the pot when changing between them. But the Picture quality was really good. I did this on n64 consoles snes jr and 2 diffrent sega genesis consoles. one was a VA2 board revision which I fully recaped and for some odd reason this one had the better picture quality of the two less jailbars also, not sure if it was because of the recap being that I did not test the console before recapping. the 2nd genesis was a VA4 model 2 genesis which had superb sound quality but was not recapped and had pretty bad jailbars, also had some slight streaking that I was unable to resolve, I want to do some more testing and recap the console however I no longer have it. Also with the snes jr it had the regular srgb encoder, I put a ncs2553 in place of it to give better rgb output before the component encoder the picture quality was really good, but in dark screens there was some very slight noise in the picture that I was unable to resolve I was thinking possibly these things could be caused by old caps on board but not really sure. The n64s were perfect no noise or jailbars in picture they were superb on just about every display I tried them on except for a vizio lcd, maybe it was the tv, anyways this is a good encoder over all but a lil touchy, I did like the ba6592f a bit better as far as sync was concearned just because you didnt need a pot on the sync line and it makes for more user friendly for customers, however picture quality comes first so I go for the ba7230ls.
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    The medium-sized mang. Raging in the Streets Lastcallhall's Avatar
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    Well that's the problem - like Drakon said, the green values are tv dependent, so what worked for one won't necessarily work for someone else. That's another reason that I used pots: they can be adjusted by the end user if things don't work out.

    I'll post values soon - I have a minor emergency in the house to deal with first.

  11. #161
    Co-Creator of the MegaAmp Raging in the Streets villahed94's Avatar
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    OK. All the TVs I tested my circuit on have the same issue, ALL OF THEM! Regardless it was LCD, LED or CRT.


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  12. #162
    Co-Creator of the MegaAmp Raging in the Streets villahed94's Avatar
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    OK. I went to experiment with the Sync line and curiously enough when I ommited the 2.2k resistor ,the greening became more severe.
    However, when I didn't connect the Sync line I got a very good image(although shaky) with almost no greening at all!
    I'm going to test adding 10k and 100k to the existant 2.2k resistor

    EDIT: Those values are waay too high. 3.3k gave me a very weak sync , but with better colours. I'm going to try 2.7k and 3k

    EDIT2: 3.1K is a pretty nice value, going to test with 3.3 and 3.5k
    Last edited by villahed94; 01-06-2013 at 09:35 PM.


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  13. #163
    Creator of the Mega Amp Raging in the Streets Ace's Avatar
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    Looks like I may need to modify the circuit with a POT on the Composite Sync. I also came across some pretty severe sync issues with the Genesis on the Samsung SyncMaster 244T 24" computer monitor (which doesn't like 240p through Component and shifts the image upwards considerably) and the Toshiba 26HL37 26" LCD TV (for some reason, I kept saying this was a 32" TV, but it's actually 26" - it supports 240p via Component, but has REALLY nasty deinterlacing on 240p and 480i sources). While Master System games are fine, Genesis games either have severe sync issues or the displays don't pick up the video signal at all. Looks like adding a POT would be a good idea. What I would like to know is how the BA6592F mixes Composite Sync with Luminance since, unlike the BA7230LS, Composite Sync is mixed with Luminance BEFORE the signal gets fed back into the encoder. No such thing with the BA7230LS. Unless... you feed back Luminance into the chip and feed Composite Sync into the chip? Might this work?
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  14. #164
    Co-Creator of the MegaAmp Raging in the Streets villahed94's Avatar
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    I'm going to check that tomorrow.

    BTW, at 5k the image is pretty decent, with colours close to the proper ones. The greening is still there, but at that resistance fringing issues appear.

    EDIT: Checking the block diagram, it shows me that if you feed Luma back into the chip and you input Sync, they get mixed and it results into the "Video out" pin (Pin 1). I have an idea about feeding the luma back, and amp the video out with a transistor, and treat it as our Luma. The question though is: Should the Luma be fed back unamplified or after being amplified by the transistor. I guess it should be unamped.
    Last edited by villahed94; 01-07-2013 at 01:03 AM.


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    Co-Creator of the MegaAmp Raging in the Streets villahed94's Avatar
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    OK, that was useless. Mixing both signals doesn't give out anything useful at all. Tested both with an unamped and an amped luma.
    BTW, I can't test anymore for now because my iron tip broke down.


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