Using a box's passthru to feed a digital TV? - AVS Forum
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post #1 of 20 Old 11-21-2009, 08:04 PM - Thread Starter
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I've got a digital TV in my living room (don't get excited, it's got a cathode ray picture tube and is SD only...just has a built-in digital tuner), and i've got a converter box feeding a recorder.

Would I be able to run the antenna into the converter box and from there feed the TV?

If the passthru would let a TV's analog tuner work, would it also let the TV's DIGITAL tuner work?

I don't want to go messing with all the wiring before knowing there's a chance.

Anyone know?
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post #2 of 20 Old 11-21-2009, 10:22 PM
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Quote:
Originally Posted by gastrof View Post

If the passthru would let a TV's analog tuner work, would it also let the TV's DIGITAL tuner work?

Yes. The so-called "analog passthrough" feature is misnamed, because it simply passes all the channels through when the box is "off". It doesn't strip out the digital channels and leave only the analog ones, which would require very sophisticated processing.

For your situation, the catch is that (as far as I know) the analog passthrough feature is always "all or nothing." That is, if you have the converter box on, no signal reaches your TV's tuner, and if the converter box is off, no signal reaches your recorder. So if you want to be able to record one channel and watch another one simultaneously on your TV, you need to split the antenna feed first, then feed part of it to the converter box and part of it directly to the TV. Your TV doesn't need the converter box because it has its own digital tuner.
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post #3 of 20 Old 11-21-2009, 10:26 PM
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Quote:
Originally Posted by gastrof View Post

I've got a digital TV in my living room (don't get excited, it's got a cathode ray picture tube and is SD only...just has a built-in digital tuner), and i've got a converter box feeding a recorder.

Would I be able to run the antenna into the converter box and from there feed the TV?

If the passthru would let a TV's analog tuner work, would it also let the TV's DIGITAL tuner work?

I don't want to go messing with all the wiring before knowing there's a chance.

Anyone know?

I suppose that your goal is to allow recording one channel while watching another.

As with the Magnavox 2160 I would think that a CECB pass through is a pass through no matter if the downstream device has an analog or digital tuner.

Your questions raise other connectivity/functionality questions related to the different methods by which CECBs implement the "pass through." Some CECBs implement the pass through when they are powered off (Zenith/Insignia) while others implement the pass through with a menu selection and the converter box remains powered on (Magnavox/Philco).

Perhaps those with a powered on pass through have some type of electronic switching or even offer some little amplification to the signal as it's passed through but powering the converter box off disables the pass through feature.

Perhaps the powered off pass through models are similar to DVD recorders with modulated RF outputs that cease to be modulated when the device is powered off.

The method used to implement the pass through probably determines the answers to connectivity/functionality questions.

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post #4 of 20 Old 11-22-2009, 07:49 AM
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Quote:
Originally Posted by gastrof View Post

If the passthru would let a TV's analog tuner work,
would it also let the TV's DIGITAL tuner work?

In a word ... YES

Quote:
Originally Posted by gastrof View Post

Would I be able to run the antenna into the converter box and from there feed the TV?

Trick is to use a CECB box with RCA-Video or S-Video outputs,
and use a CECB box that also performs A.P.T. while powered on.
(A.P.T. = Analog Pass Through)

Antenna >>> CECB >>> Recorder >>> TV

Just connect the RCA or S-Video output of the CECB
to the corresponding input on your recorder.

Record one / Watch another:
1 - Select channel on CECB to record.
2 - Select line input on recorder and start.
3 - Select pass-through on both units.
4 - Watch any channel on TV simultaniously.

No splitter causing loss this way.

Additional Benefit:
By connecting the line out of the recorder to the TV,
you can check on your recording once in a while easily.

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post #5 of 20 Old 11-22-2009, 03:10 PM
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Quote:
Originally Posted by WeThePeople View Post

In a word ... YES

Trick is to use a CECB box with RCA-Video or S-Video outputs,
and use a CECB box that also performs A.P.T. while powered on.
(A.P.T. = Analog Pass Through)

Antenna >>> CECB >>> Recorder >>> TV

Just connect the RCA or S-Video output of the CECB
to the corresponding input on your recorder.

Record one / Watch another:
1 - Select channel on CECB to record.
2 - Select line input on recorder and start.
3 - Select pass-through on both units.
4 - Watch any channel on TV simultaniously.

I believe Gastrof may be using a DTVPal.

It will pass through a digital signal when powered on or off, but will not work to record one / watch another as you described.
When the DTVPal is put in (powered on) analog pass through, there isn't any signal available from the RCA video/audio outputs.

Only a few brands/models will work as you suggested. (RCA outputs active during powered on pass through.)

When the DTVPal is powered off, the pass through signal will be interrupted occasionally, when it does maintenance.
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post #6 of 20 Old 11-23-2009, 04:39 AM
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Thank you for that Beeper,
he was a bit light on equipment details.

I searched his posts and found this:
"I have a TR40 and 970A on order"

I'm near sure the TR40 and the 'Pal are identical hardware,
is the (APT) firmware implementation the same too?

Could those knowledgable of these two CECB's
confirm APT style used, to confirm applicability?

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post #7 of 20 Old 11-23-2009, 08:34 AM
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Quote:
Originally Posted by WeThePeople View Post

Thank you for that Beeper,
he was a bit light on equipment details.

I searched his posts and found this:
"I have a TR40 and 970A on order"

I'm near sure the TR40 and the 'Pal are identical hardware,
is the (APT) firmware implementation the same too?

Could those knowledgable of these two CECB's
confirm APT style used, to confirm applicability?

The TR40 and Pal are virtually identical.

The Zinwell 970A is reported to have active RCA outputs when in (powered on) pass through, according to a post by systems2000.
The only other CECB that I am aware of that reportedly would work similar to the Zinwell for the stated purpose is the Philco TB100HH9.
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post #8 of 20 Old 11-23-2009, 12:39 PM
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The Zinwell 970A will do the job BUT he'll have to keep it powered up to use his digital TV even when not using the recording setup. The signal still passes through when the 970A is off but is very weak. The component (RCA) outputs do stay active in APT mode.

I don't know of any boxes that do this AND pass-through when powered off, but I don't know them all (this forum would be a good place to list this info). Ideal would have been designed like a VCR (TV/VCR switch & active composite out).

I would have liked to have done this too to save the splitter loss but chose to be green (plus the hassle of having to remember to turn it on and APT on). Too bad the CM doesn't have APT as it's my equivalent of his digital TV in the setup (I suspect the TV doesn't have RF pass-through).

The Zinwell 950A APT only works while the box is off.
The Artec T3AP-LL APT only works while the box is off.
The Artec T3A Pro does not have APT.

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post #9 of 20 Old 11-23-2009, 06:02 PM
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I either hadn't tested the 950A for that ability or had forgot that it had changed. I took a look at mine and did find that Zinwell had removed the option, from the "Setup" menu.
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post #10 of 20 Old 11-24-2009, 09:37 AM
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Also, the 970A's remote has a DIGITAL/ANALOG button not on the 950A's remote; when I use this remote>button on my 950A it turns the box off (how fitting! LOL).

I had assumed the 950A came before the 970A (# and remote #) but hard to say the way these wacky manufacturers flip their model numbers around (I suspect some do it to fool the consumer).

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post #11 of 20 Old 11-24-2009, 10:28 AM
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The TRT 2009 has an RF on/off option.
I haven't confirmed if that acts as a pass through yet.
It has no effect on the RCA/S-video output.
Same with the LPCM/raw data option.
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post #12 of 20 Old 11-25-2009, 12:03 AM
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Quote:
Originally Posted by Floydage View Post

Also, the 970A's remote has a DIGITAL/ANALOG button not on the 950A's remote ...

That button is on the remotes only of the later, blue-box 970A's [EDIT: and on only some of those at that].  I don't know what they'd do on an earlier, orange-box 970A such as the 0830 unit I have, which come with remotes that don't have that button.
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post #13 of 20 Old 11-25-2009, 09:11 AM
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My "Blue" box ZAT-970A (0920) has the ZRC-4501 remote (without the APT button), not the ZRC-4502 remote (with the APT button).

EDIT: The ZRC-4502 remote (from my ZAT-950A) APT button has no effect on my ZAT-970A (0827), although the shifted buttons still work the same.
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post #14 of 20 Old 11-25-2009, 10:38 AM
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So where is Gastrof hiding? He hasn't eluded to exactly why he wanted to wire the tuner as he stated, other than passing through a digital TV signal.
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post #15 of 20 Old 11-25-2009, 12:29 PM
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Baffling! All of my ZAT-970As (0914, 0920, and 0940) came in blue boxes with the ZRC-4502 remote.

My ZAT-950A (0901) came in a purple box with the ZRC-4501 remote.

My boxes also have a picture of the remote on the top that matches the contents.

I suppose I need to use "my" instead of "the" when describing this stuff.

systems2000, maybe your remotes got mixed up between your 0920 and ZAT-950A?

I would have gladly sacrificed the APT button for the hidden EPG.

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post #16 of 20 Old 11-25-2009, 12:42 PM
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Quote:
Originally Posted by Beeper View Post

So where is Gastrof hiding? He hasn't eluded to exactly why he wanted to wire the tuner as he stated, other than passing through a digital TV signal.

He was trying to use the converter box as a tuner for a recorder while passing through to his digital TV (saves a power split). Oddly enough, very similar to this topic started a day earlier:

http://www.avsforum.com/avs-vb/showthread.php?t=1198317

The planets align.

Appears to be a pretty common situation. Part of my gripe about the gov't leaving non-digital tuner recorder folks in the dust. Lots of VCRs out there.

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post #17 of 20 Old 11-25-2009, 08:06 PM
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Baffling! All of my ZAT-970As (0914, 0920, and 0940) came in blue boxes with the ZRC-4502 remote.

My ZAT-950A (0901) came in a purple box with the ZRC-4501 remote.

My boxes also have a picture of the remote on the top that matches the contents.

I suppose I need to use "my" instead of "the" when describing this stuff.

systems2000, maybe your remotes got mixed up between your 0920 and ZAT-950A?

Not baffling at all. I checked the boxes, that my ZAT's came in, and they show I was mistaken. The ZRC-4502 came with the 0920 (not the 950A), although the ZRC-4502 does work on the 950A.

I really believe that if there was a way to remove (copy for distribution) the firmware from a 0930 or earlier, everyone would want it. Same goes for the 1st run of the Sunkey SK-801ATSC units.
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post #18 of 20 Old 11-25-2009, 08:07 PM
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post #19 of 20 Old 11-26-2009, 09:27 AM
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Quote:
Originally Posted by systems2000 View Post

I really believe that if there was a way to remove (copy for distribution) the firmware from a 0830 or earlier, everyone would want it.

Well I'll be watching the threads for that one.
______________________________________

OT: These portable digital TVs I see in recent ads got me wondering how well they tune with that short monopole antenna? The analog versions had a hard enough time as it was.

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post #20 of 20 Old 11-26-2009, 09:46 PM
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Quote:
Originally Posted by Floydage View Post

OT: These portable digital TVs I see in recent ads got me wondering how well they tune with that short monopole antenna? The analog versions had a hard enough time as it was.

With the builtin - forget it...

If you can hook it to a REAL antenna - it should probably work.

You CAN put antennas on your owned and/or controlled property...
http://www.fcc.gov/mb/facts/otard.html

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