Series 3 (OLED) Tuning Issues

Discussion in 'TiVo Series3 HDTV DVRs' started by danplaysbass, Feb 29, 2012.

  1. danplaysbass

    danplaysbass I watch too much TV.

    707
    0
    Jul 19, 2004
    Philadelphia

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    Hi Guys,

    I was in here a few months back discussing a problem I was having with tuning on my Series 3 OLED.

    http://www.tivocommunity.com/tivo-vb/showthread.php?t=480756

    The problem is back and with a vengeance. Also, I'm not sure if maybe there aren't some additional problems at play here as well.

    It started with the fact that cablecard 1 was unable tune. It would just go to a blank screen. I ended up replacing the cable card and that seemed to fix the issue. Not too long after occasionally I would have a grey cablecard diagnostic screen popup requesting that I call TWC (Kansas City) and authorize the card. I called them and they verified that they were authorized and could communicate with the card.

    A few weeks later the TiVo started missing shows because it could not tune those channels. It was never the major network shows, only the one in the cable package. I later learned that these are the switched digital channels. It got so bad that if I tried to tune to anything but a major network that cablecard screen would keep popping up. Just 2 days ago we started having some problems on even the network channel while watching live (but buffered) where it would start to stutter and pixelate making everything unwatchable.

    I called TiVo support and they suggested that I pull up the signal strength meter. I was consistently hitting 95-100 on the higher channels so the tivo guys said we needed to knock it down.

    I had a TWC guy out yesterday and we removed almost 15dB of power from the signal and the power meter on the tivo was still maxed out so I'm not putting too much stock in how well that works.

    Anyways, we swapped the cable cards and the problem seemed to follow and moved to cablecard 2. Then we started having problems with both tuners within a few minutes. We replaced both cards and the problem still persisted.

    My only next step involving TWC is to replace the tuning adapter with I plan to do today.

    I have read that these Series 3 units have power supply issues (I can fix that no problem). From your experience do these problems seem TiVo related or cable related? What are the symptoms of power supply failure and hard drive failure? Any other suggestions?

    Thanks in advance for your help!
     
  2. unitron

    unitron Well-Known Member

    16,595
    62
    Apr 28, 2006
    semi-coastal NC
    Everything in the TiVo has one thing in common.

    The power supply.

    S2s and S3s are known to have power supply problems caused by bad capacitors.

    Go read the wikipedia page on capacitor plague.

    Then go find a thread entitled "broken" in the Help forum here at TCF for steve614's excellent picture showing how subtle the visual difference between a good capacitor and a failed one can be.

    Then take the lid off of your TiVo, after unplugging it from the wall socket, and take a good hard look at your power supply.

    If you know how to use a voltmeter, the yellow wire is the +12, the red is +5, and the orange is +3.3 and they should all read within a few percent of nominal, without fluctuating.

    If there's nothing wrong with the power supply, you've eliminated one of the variables, and are that much closer to finding out what is causing the problem.
     
  3. danplaysbass

    danplaysbass I watch too much TV.

    707
    0
    Jul 19, 2004
    Philadelphia
    Thanks unitron. I'll have no problem checking out the PS. I'm an electrical engineer with all the tools I need to repair it but I was just more wondering if anybody experienced anything similar.
     
  4. danplaysbass

    danplaysbass I watch too much TV.

    707
    0
    Jul 19, 2004
    Philadelphia
    Ok. Update. I replaced the tuning adapter with no fix to the problem. I popped the lid and the 12V power is only running about 7.5 volts so that must be the problem (or part of it).

    I have no problem changing the caps inside but is there a schematic or diagram for which ones to replace?
     
  5. unitron

    unitron Well-Known Member

    16,595
    62
    Apr 28, 2006
    semi-coastal NC

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    Depending on the model, there's probably one or two in the neighborhood of 2200uF on the +12V output rail, and another one or two on the +5V output rail.

    I'm sure there's at least one on the +12 that's bulgy, but if it's got two in parallel replace both, because if one was bad that threw its share of the work on the other one.

    Find where the yellow wire solders into the board and look for caps with their + leads soldered to the same land and their - leads soldered to ground (black wire). That's the 12V output.

    Do the same with the red wire. That's the 5.

    The 3.3 (orange wire) is probably alright, but see if there's a cap between it and ground, and check it for bulges or leaks as long as you've got the hood up.

    And, of course, replacement caps should be the same value, the same or slightly higher working voltage, low ESR, and rated for 105 degrees Celsius (or have they gone back to calling it centigrade?).
     

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