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Handling different tint for different sources
I couldn't think of the actual subforum for this.
Apparently I have some seriously crappy sources. My Roku, Sega Genesis, and DTA all require drastically different tint settings on my TV, just to be correct. Luckily on all of them, I can pull up the SMPTE patterns (even on the Sega with a special test cart). Let's see. Sega: -19 DTA: +4 Roku: +13 I have never seen equipment so out of whack like this, but the TV's I have, are either the knob types, or the OSD menu types that sadly only treat the tint setting globally and not per input. Is there any possible way to shift the hue with a circuit I can construct from the composite video signal, to add some form of correction? It's getting so old changing the tint settings just when I decide to watch something different. It's a minor nitpick, I know, but damn, I've never seen such drastic differences in the sources like that.. Sad thing is, I think the only one that's actually accurate, is the Sega Genesis, ironically. It matches perfectly with my Sencore generator. (I know the Sega internally is RGB and is converted to NTSC, and the DTA and Roku's are both internally Y/Cr/Cb and converted to NTSC--maybe that's why?) |
#2
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There's a reason NTSC was nicknamed Never The Same Color twice.
This was a common issue going from Station to Station back in the days of Broadcast TV. |
#3
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Quote:
If it is a crystal frequency difference problem, I don't know of a simple solution. It would require a proc amp with adjustable burst phase for each source or going into each device and finding a way to retune the color oscillator. |
#4
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There's gotta be a way to make a circuit that shifts the color burst signal slightly. I'm hoping that simply shifting the color burst is all it'd take to correct the tint. Saturation or anything else I don't care, I just want the tint looking right. something I can manually set per input, to some "reference" which would be my TV at "0". |
#5
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Aw geez, another "something is wrong, but I aint giving any clue as to what Brand or model of TV we're dealing with.....
'Tis a Secret? Some of us have RESOURCES to help, but you gotta give us some meat on the bone.....
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Brian USN RET (Avionics / Cal) CET- Consumer Repair and Avionics ('88) "Capacitor Cosmetologist since '79" When fuses go to work, they quit! |
Audiokarma |
#6
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Wow.. Chill. Thought I made it clear it's happening to ALL TV's.
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Want a specific model? Here, Sony PVM 1390. But out of every TV in the house, the problem is the SAME. Last edited by lnx64; 08-26-2017 at 10:02 PM. |
#7
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This is overkill but I'll just save up for a few of these if I can't find any better solution..
http://www.allaboutadapters.com/vitibacowifr.html So far the only thing that'll shift the tint of the SOURCE, as it's not a TV problem, happens on all TV's. Last edited by lnx64; 08-26-2017 at 10:00 PM. |
#8
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There is one fishy thing here, though, and that is that all your sets behave the same (is this exactly true? or is the amount of error different?). The same magnitude of error on all sets could indicate that the effect is not due to chroma frequency (which you would expect to produce an error in the same direction but different amounts in different sets), but could actually be due to burst phase errors in your sources. This conceivably could be fixed if you could get into the right place in each source hardware and adjust the burst phase. However, if that adjustment is fixed somewhere internal to an IC in the device, you are out of luck. Last edited by old_tv_nut; 08-26-2017 at 11:04 PM. |
#9
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The amount of error isn't quite the same, but it's in the same relation to each other (like the Sega and Sencore are both polar opposites to the DTA and Roku). Then again, each sets tint control is different, so I couldn't say for certain, I'd need to hookup my scope and really see what's going on.
About the only system I can adjust is the Sega Genesis, but it would entail an adjustable oscillator on the Sony RGB to Y/C converter that's in it. (Well technically I use a 32X on my Genesis, and THAT is what generates the composite signal, not the Genesis--and it does have an adjustable capacitor that does modify the hue also, along with other things.) It's either this or just get the equipment to modify the sources, and being the Sega is actually close to matching my Sencore, I'd have to modify something that's actually correct. But it's beginning to seem like the only other option is the expensive soute. |
#10
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now you can understand why PAL and SECAM were developed...
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____________________________ ........RGBRGBRGB ...colour my world |
Audiokarma |
#11
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If you have a bunch of video capable OP amps around, lots of time, and like analog circuit design, then it might be possible to design and build such a device. You would need to strip the color burst, create a new phase shifted burst and add it back.
Probably would want to create the new burst from the old one...Using something like the color osc/sync circuit from a TV/monitor and modifying the H AFC sync feedback control system for the oscillator or creating a variable phase delay in the incoming sync such that you could manually control the phase delay. Might even be able to just separate the burst, phase shift it and re-add it.
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Tom C. Zenith: The quality stays in EVEN after the name falls off! What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4 |
#12
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or use VIR?
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Rick (Sparks) Ethridge |
#13
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VIR has to exist natively in the source (only was broadcast for a few years, several decades ago), and be built into the set. Neither of which is practical to achieve in his system....
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Tom C. Zenith: The quality stays in EVEN after the name falls off! What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4 |
#14
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I might have found a possibly easier method for this.. The Roku, the furthest off from the other two sources, is using an HDMI to composite adapter. I took that adapter apart, and I might be able to do something with it. If I can get that closer, I'll care less about the DTA because I don't watch much OTA TV anymore, it's all smut and crap on these days.
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#15
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I would just suggest getting a better TV, you can probably pick up a high end Sony XBR or Panasonic Tau from the early 90's for little or nothing.
In addition to just flat out having better color rendition than a $99 Apex these sets will have multiple composite/component inputs with individual settings for each one. |
Audiokarma |
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