1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Tivo HD Pixelation Troubleshooting

Discussion in 'TiVo Series3 HDTV DVRs' started by Chimpware, Aug 3, 2007.

  1. Dec 4, 2011 #1541 of 1597
    unitron

    unitron Active Member

    16,387
    2
    Apr 28, 2006
    semi-coastal NC
    All OK except the one that was bulging and needed to be replaced?
     
  2. Dec 4, 2011 #1542 of 1597
    classygal31

    classygal31 New Member

    4
    0
    Dec 3, 2011
    That's what the repairman said, although with my Tivo Series 3 still acting up I'm a little suspicious. I took it apart again, examined all the capacitors in the power supply and they all appear to have completely flat tops. If I completely remove the cable cards, the Tivo works fine. I've replaced the cable cards in the last few days on advice of Tivo support. I'm pretty sure it's the power supply, but just not obvious which other capacitor is bad or maybe something else within the power supply?
     
  3. Dec 4, 2011 #1543 of 1597
    unitron

    unitron Active Member

    16,387
    2
    Apr 28, 2006
    semi-coastal NC
    Somebody else around here the other day ran into the "adding cable cards adds just enough extra load to cause problems" problem, and I seem to recall power supply repair fixed it.

    Ask the repairman if he/she used a low ESR replacement. The only acceptable answer is yes.

    Ask them if there was another capacitor in parallel on the same output rail with the one they changed out. (there probably was and it was probably the +5 Volt rail)

    If so, it was in a situation where it was trying to do the work of both and I'd replace it as well just on general principles.

    Get them to look at the +3.3 Volt and +5 Volt outputs with an oscilloscope and watch what happens when a cable card is inserted.
     
  4. Phantom Gremlin

    Phantom Gremlin New Member

    1,555
    0
    Jun 20, 2002
    Tualatin,...
    Hmmm, just like reading the TV repair column in the old Radio Electronics magazine. First debug tip was "scope the B+". :)
     
  5. unitron

    unitron Active Member

    16,387
    2
    Apr 28, 2006
    semi-coastal NC
    "For Men With Ideas In Electronics"!:)
     
  6. classygal31

    classygal31 New Member

    4
    0
    Dec 3, 2011
    Ok. It just so happens that in the time it took for me to get back here to read this post, my Series 3 is now rebooting without the cable cards in it. I'm going to replace the entire power supply. I've been watching eBay, however, it seems the Series 3 prices are being jacked up due to the holidays. They are going for $70+, so I'll have to wait until next month to find a deal.
     
  7. unitron

    unitron Active Member

    16,387
    2
    Apr 28, 2006
    semi-coastal NC
    Get your guy to replace the one he replaced and all the ones in parallel with it with Low ESR caps rated for 105 degrees Centigrade.

    Try it like that for a while.
     
  8. debsmusings

    debsmusings New Member

    5
    0
    Aug 20, 2012
    Are you still seeing pixelation issues on Comedy Central? I am researching this issue that I have been seeing for over a year and am trying to see if I can document other problems in the TIVO community.

    I use FIOS and regularly have pixelation problems with The Daily Show, Colbert Report and TOSH.0
     
  9. unitron

    unitron Active Member

    16,387
    2
    Apr 28, 2006
    semi-coastal NC
    Chances are whoever you get that channel from has a problem with the satellite downlink during those times, or else Comedy Central has a problem with their satellite uplink.
     
  10. debsmusings

    debsmusings New Member

    5
    0
    Aug 20, 2012
    That may be the case. My problem is that its hard to get these kinds of issues percolated to the source of the problem without evidence that multiple users are seeing this problem. So I am wondering how many TIVO users are having pixelation problems with their Comedy Central HD channel. I am on FIOS but I see that other users of other systems also see similar problems.

    I am thinking ultimately it could be a comedy central problem. But it won't get treated at the source if I am the only one complaining.
     
  11. unitron

    unitron Active Member

    16,387
    2
    Apr 28, 2006
    semi-coastal NC
    And as long as the uplink and downlink pass through the atmosphere, it may be incurable.
     
  12. astroglide

    astroglide New Member

    31
    0
    Jun 20, 2005
    S3 TCD648250B with a single 1TB drive and dual M-cards. It started pixelating, and I've discovered that removing a single card is enough to completely resolve it. No other issues - it works perfect with one tuner, using either card. Is there a typical cause for this symptom? Thx!
     
  13. unitron

    unitron Active Member

    16,387
    2
    Apr 28, 2006
    semi-coastal NC
    One possible explanation is the power supply is falling victim to "capacitor plague", and the extra power demand of the extra card is enough to push it beyond its current ability to reliably supply current.

    If it's an S2 or S3 with strange symptoms, suspect the power supply caps, especially the ones on the +5 and +12 V outputs, first.
     
  14. astroglide

    astroglide New Member

    31
    0
    Jun 20, 2005
    Popped the top and checked the caps: one leaking, one bulging. Thx for the pointers! I figure I might as well replace all of them, and I see people starting to put lists together in threads like this one. Anyone know if there's a full kit out there for the S3 OLED PSU a la the badcaps.net motherboard kits? Would love to add just one batch item to a cart and check out with confidence. I did email badcaps about it, BTW.
     
  15. unitron

    unitron Active Member

    16,387
    2
    Apr 28, 2006
    semi-coastal NC
    Replacing all of the caps is usually overkill, as it's most often just the ones on the 5 and 12 outs that fail, and the more of them the home gamer has to replace the greater the chances of putting one in backwards or getting two of them swapped, and although unlikely, it's not impossible that there's some other component gone bad (or that there's also a problem that's somewhere other than on the power supply board), so anyone offering a "kit" has to be ready to deal with buyers who come back yelling they've been cheated.
     
  16. astroglide

    astroglide New Member

    31
    0
    Jun 20, 2005
    Okay okay, you've sold me :) Ordering just the three bad ones, for now. Thx, unitron!
     
  17. unitron

    unitron Active Member

    16,387
    2
    Apr 28, 2006
    semi-coastal NC
    Find all of the ones with their negative leads connected to the black wires via the copper on the bottom of the board, and with their positive leads connected directly to either the red or yellow wires, and replace all of them.

    Haven't yet had my hands on that particular PS before, so I don't know how many caps that would be, although probably no more than 2 per voltage (i.e., 2 on the red and 2 on the yellow)

    Of course any other visually bad (and any that are electrically in parallel with them if you know how to determine that) should also be replaced.

    If the place where the negative lead of a cap comes out the bottom of the board is directly connected to where the negative lead of another cap is connected, AND the place where the positive lead goes through is also directly connected to the positive lead of the second cap, that's being in parallel, and if one had gone bad, the other's been trying to do the job of both, and has probably suffered for it.
     
  18. GerryFR

    GerryFR New Member

    12
    0
    Aug 7, 2003
    I have been having problems with my two HD Tivos (Series 3 and HD) for several years with lost channels and pix-elation. I have had numerous Cox service calls but most ended with replaced cables and with blaming me for putting the coax cables where they could be bent or stepped on.

    The Cox tech, that came out to my house today, fixed my Tivo problem, but it took him about two hours to do it. It seems that there are two sets of channel signals in this Cox system, the older analog signals, and the newer HD signals. The front end of the Tivo, as well as any other tuner device, had an automatic gain control on the input RF signal so that the receiver in the tuning device had the proper signal level going into it. Unfortunately, if these two types of channel signal levels are too far out of balance, the AGC circuitry, in the Tivos, would attenuate the input signals down so that the most powerful signal was adjusted properly but this meant that the lower power signals would get attenuated down to where some of the channel signals would be too low for the Tivo tuners. This would result in pictures breaking up and missing channels.

    The tech took channel signal level measurement on a special spectrum analyzer meter, that he carried, and found that my channel signal levels were severely out of balance. To fix the problem, he put several filters in line with my cable input, which lowered the power level of the higher frequency channels to make all signal levels the same value. Two filters, in series, were required to attenuate the signal enough. Once the signal levels were the same, he then found that both signal levels were now too low to work properly. He then needed to amplify the incoming signals to get them to the proper power level. He did this by putting an amplifier, outside, in front of the outside power splitter and powered it with a power injector module that I power with a standard power supply module in my living room. With the amplifier in place, both of my cable outputs now had the proper power and noise levels. We had to restart all of the Tivo's associated equipment, but once they were running again, my channel and pix-elation problems went away on both Tivos. It took him several hours to do the job, but it was worth the wait. It was ironic, that when these previous Cox techs fixed any "bad" coax cables, that I had, that they actually made the power differential between these two different sets of channel signal levels greater. The higher frequency channel signal levels would improve the most, with the cable improvements, and that would result in the Tivo's AGC circuitry attenuating the input signals even more. That is why my Tivo problems got worse with each service call.
     
  19. unitron

    unitron Active Member

    16,387
    2
    Apr 28, 2006
    semi-coastal NC
    Very interesting and informative. Are all of the "digital" channels fed at a higher frequency than the analog channels on your system? It would seem that the AGC should be reacting in real time to the level of the particular frequency being tuned regardless of the levels of other frequencies.

    Of course if the digital channels are interleaved in any way with the analog ones, then strong adjacent channels could perhaps swamp the AGC regardless of modulation scheme.
     
  20. dlfl

    dlfl Cranky old novice

    6,996
    16
    Jul 6, 2006
    Near...
    Would have been interesting to see what Signal Strengths were reported in DVR Diagnostics for the high, low, and medium frequencies (before the tech did all the adjustments). I suspect they would have been outside the ranges where TiVo works properly (roughly 60 to 99) due to too much "tilt" at the cable tap, which means the tech was turning cartwheels to compensate for poor initial setup of the neighborhood distribution system. lrhorer has given a detailed explanation of "tilt" here:
    http://www.tivocommunity.com/tivo-vb/showthread.php?p=7604378#post7604378
    Of course if neighbors with Cable Co equipment were not experiencing problems this suggests TiVo tuners are just not as robust as they should be.
     

Share This Page