Zenith DTT901 - Page 77 - AVS Forum
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post #2281 of 2288 Old 10-31-2014, 01:58 PM
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I've been trying to figure out why the converter boxes do some of these strange things, as most of them do lock up in various ways. In most cases it seems to be that the signal gets corrupted and the PIDs that the box sees do not match the channel info that they have for the channel and that gives them trouble--usually just requires changing channels to fix. But sometimes the signal get so corrupted that the boxes go into an error mode and rather than reboot under that condition the box just stays in the error mode.
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post #2282 of 2288 Old 10-31-2014, 03:01 PM
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I've been trying to figure out why the converter boxes do some of these strange things, as most of them do lock up in various ways. In most cases it seems to be that the signal gets corrupted and the PIDs that the box sees do not match the channel info that they have for the channel and that gives them trouble--usually just requires changing channels to fix. But sometimes the signal get so corrupted that the boxes go into an error mode and rather than reboot under that condition the box just stays in the error mode.
They were designed to government specifications and to be produced for as low a cost as possible.

That means lower cost parts which will mean a short intended life span and many problems.

----------------------------

When I ordered my top of the line RCA last analog NTSC TV the sales person explained that the set I ordered was built on the same production line as a cheaper model, but with better components.

Spending top dollar paid me back a huge amount in enjoyment. It controlled my VCR almost as well as I control my HTPC with a program I just reinstalled as the paid listings server will change at midnight.

http://www.avsforum.com/forum/26-hom...-new-post.html

SHF
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post #2283 of 2288 Old 11-01-2014, 11:03 AM
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Quote:
Originally Posted by jvvh5897 View Post
I've been trying to figure out why the converter boxes do some of these strange things, as most of them do lock up in various ways. In most cases it seems to be that the signal gets corrupted and the PIDs that the box sees do not match the channel info that they have for the channel and that gives them trouble--usually just requires changing channels to fix. But sometimes the signal get so corrupted that the boxes go into an error mode and rather than reboot under that condition the box just stays in the error mode.
Yeah that is the case on my CM, changing the channel and powering off then back on didn't work. It seemed to do the interline bit the most when watching football on certain stations, maybe something with the football field grid lines; I think NFL Monday Night Football when it was on NBC was the most common for me.
I've read of other boxes with the potential PID problem you mentioned.
One model of Zinwells gives me a pixelation problem when there's noise on the same AC line like a fan turning on. Retuning the channel cures it. Looks like insufficient power supply filtering inside as these use a simple wall-wart. I have another model of Zinwell that doesn't have this problem yet it uses the same wall-wart, but it uses a different tuner and maybe a different MPEG decoder IC.

I think these type of problems have more to do with lack of thorough software testing&debug than cheap parts. Parts are parts for the most part in this day and age (although some of the more complex ICs could be the same software culprit if they were designed only for these inexpensive tuner boxes - ex: if they weren't produced for HD output use too). It takes a lot of engineering resources and time to thoroughly test modern digital electronics, plus when these were designed there wasn't a lot real world and finalized infrastructure to system test.

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post #2284 of 2288 Old 11-03-2014, 08:44 AM
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I've had rca, channel master, and higher end digital stream boxes to play with and all had the trouble that seems to be PID corruption during signal acquisition trouble. All seems to have the error on other corruption issue too--at least all seem to have to be rebooted by a power cycle. My best guess is that since they are diff platforms and diff processors, that the only common element is the code that came from the ATSC format owners--I'm guessing that they supply flow diagrams or sample code for various core functions (like signal acq) and the box programmers just wrap that in the user interface as is (maybe they are prohibited from changing the core functions as part of license). If that is true then all of the boxes and TVs that follow the ATSC format have built in bugs.
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post #2285 of 2288 Old 11-03-2014, 10:09 AM
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Never had these kind of problems with my Zinwells, Artecs (although my Artecs haven't been used much), and HD tuners. My HD tuners are from way before CECBs; One is a Hughes DirecTV right before they started requiring sat. subscription for the ATSC to function 'freely' and one is Motorola's first HD tuner.

What's odd on the CM is that I have to pull the plug live to fix it. When I plug it back in it goes through some kind of unique display cycle that I don't see on normal power on, kind of lack they do out of the box but without any setup screen.

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post #2286 of 2288 Old 12-03-2014, 03:35 PM
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Guide Limitations on the 900/901?

What are the guide limitations? Always thought it was 2 pages, but on one of my PBS subs I noted 7 pages of program summary on certain programs.

My Westinghouse TV only gives 2 lines, then cuts it off, shows an arrow but no way to scroll down.

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I've been trying to figure out why the converter boxes do some of these strange things, as most of them do lock up in various ways. In most cases it seems to be that the signal gets corrupted and the PIDs that the box sees do not match the channel info that they have for the channel and that gives them trouble--usually just requires changing channels to fix. .
Note, the Zenith has to be on the channel to gather PID
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post #2287 of 2288 Old 12-05-2014, 01:44 PM
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I don't know the guide limits for the Zenith box as I don't own one. I've seen a lot of variability in various other devices and in documentation--limit seems to be what the TV channel operators decide to put on the air. One TV I had would do about 8 hours of guide on PBS, but it took 10 minutes or so to gather the last couple of hours of that.
The RCA DTA800b only does what is on and what is next.
One TV I have now only give what is on--and that is the newest device I own so you would think it would do more than older devices.
The docs for guide data suggest that TV operators send out some data very very often. A 3 hour guide every 3 minutes or so. And more data at longer intervals if they desire, but it is not required.
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post #2288 of 2288 Unread Today, 01:13 PM
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My bad I meant the program description box in the upper Left corner (which is part of the guide.... well sort of)....

That was one weak point of the Zenith/Insignia/LG, only gives you the next program, where the Magnavox/Sylvania went 6-8 hours ahead in some cases (much like the iView).... forgot how the guide was in the Apex, but believe it was still better than Zeniths.
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