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  #1  
Old 01-11-2015, 04:00 PM
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Sounds like OP had mixed up terms, I though he was asking if a set can accept component inputs- not composite.
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Old 01-11-2015, 05:15 PM
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Originally Posted by miniman82 View Post
Sounds like OP had mixed up terms, I though he was asking if a set can accept component inputs- not composite.
I'm Bad!! I meant composite I got that mixed up.
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Old 01-11-2015, 06:07 PM
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I'm Bad!! I meant composite I got that mixed up.
Has anybody here figured out a way to modify an older set to take component video? I imagine that it would be much more difficult to accomplish, but even better picture quality might be obtained.

How about an isolated input circuit for use on "hot chassis" sets?

jr
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Old 01-11-2015, 06:23 PM
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Originally Posted by jr_tech View Post
Has anybody here figured out a way to modify an older set to take component video? I imagine that it would be much more difficult to accomplish, but even better picture quality might be obtained.
jr
IIRC user Tomcomm did that on his 21CT55 along with composite video, and S-video.....I would not be surprised if he tried do VGA as well.
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Old 01-19-2015, 04:22 PM
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Quote:
Originally Posted by jr_tech View Post
Has anybody here figured out a way to modify an older set to take component video? I imagine that it would be much more difficult to accomplish, but even better picture quality might be obtained.

How about an isolated input circuit for use on "hot chassis" sets?

jr
Well, if you find the "right" DVD player it actually isn't hard at all, for B&W sets.

By "right" I mean one that doesn't bother turning off the YBR ports when its in "composite out" mode. (Older is better, usually.) Essentially the Y (Green) outputs a standard 525 line luminance signal which on modern component inputs results in "no signal" or something not all unlike a B&W set with the horiz oscillator running at 2x normal freq. Easiest way to see if you have this type of DVD player is just whack a scope on the green jack while confirming a normal picture is coming out of the yellow or S-video connection on a normal TV set.

Just shove that signal into the appropriate point on the chassis. (You may need to rig up a phase inverter, depending on if the tuner in your chassis is positive or negative sync. YMMV.)


Edit for related ramblings:

If you're going to add a baseband input to anything B&W you should always try and feed it from an S-video jack, using only the Luma signal pin (and ground, obviously.) Unfortunately a lot of things that have "S-video out" don't actually supply both discrete Luma and Chroma signals, the really cheap crap just mixes them together or duplicates the composite signal on both pins. Same can be said for the really cheap stuff with an "S-video input" on it. Usually a resistor and cap combining the signals near the jack and feeding the result to the same point as the Composite jack goes. (I do miss TVs that had properly designed/engineered comb filters.) Poke an S-video jack with a 2 channel scope sometime to see what goes on. Ideally you're supposed to have pure 525 line Luma available, which is great for pre-color sets! As above you may need to add a sync inverter depending on your chassis. (Possibly bypass a built in sync inverter, as long as its before the vertical drive pickoff, otherwise you'll not get sync.)

Last edited by NoPegs; 01-19-2015 at 04:30 PM.
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Old 01-20-2015, 04:04 PM
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Quote:
Originally Posted by jr_tech View Post

How about an isolated input circuit for use on "hot chassis" sets?

jr
Well, the best way IS to use the set's tuner and IF strip, and the RF output of a VCR or RF modulator. There the isolation is the small caps on the tuner's input.

As for the CECB I placed inside a TV I did, I used the audio and video output jacks of the CECB to feed the baseband video into the video circuits of the TV, and the audio to audio. For this set, it was easy, as this set used to have a built in VCR that died.
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Old 02-04-2015, 05:27 PM
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I would be interested in hearing from anyone else who attempts a similar mod on a tube-type TV set of any kind. I would like to do this on several of my sets mainly because the modulator is one more box and one more power brick, and because a direct connection will give a cleaner signal. I've seen success here with an early Zenith color set, and Phil Nelson's site documents a composite input on an Admiral B&W set, that's two that I know of. My understanding is that some sets may require a signal inversion or a gain stage, so it would be interesting to document that somewhere. Has anyone successfully added a composite input to an RCA?
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