Loss of signal strength, but only on three channels

Discussion in 'TiVo Bolt DVR/Streamer' started by spatula, May 28, 2019.

  1. spatula

    spatula Member

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    Mar 31, 2014
    San Mateo,...

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    I'm gathering more data and suggestions for helping my parents troubleshoot their TiVo Bolt Vox. Unfortunately they are in Kansas, and I am in California, so I'm trying to get as many ideas as I can ahead of a lengthy phone call.

    They're using an OTA-only configuration with all their wiring indoors. Their antenna is in their attic, and traverses a surge suppressor, MoCA filter, and 2GHz splitter before reaching the Bolt. On the other side of the splitter is an ordinary TV in a spare bedroom and a Vox Mini. The Mini talks to the Bolt over MoCA.

    The TV in the spare room doesn't seem to have any problems with any channels. I haven't gotten signal strength information from this TV yet, so this might not mean anything special.

    For most channels, they have a signal strength of 72, which I understand is the highest strength a TiVo will report for an OTA channel.

    For *three* channels, which used to have a signal strength of 72, that signal is now around 36.

    Last night we tried a few things with one of those channels, 8-1, which, like many other channels in their list, has both their main channel and a translator available from my parents' location. One is on channel 8 and one is on 17. However, neither one of these worked. Both give a V53 error message.

    We've also tried a reboot of the TiVo, which failed to bear fruit.

    I haven't investigated the other two channels in depth yet, because I think it somewhat likely if I solve the problem for the main channel they're having trouble with, it's likely the same solution will apply to the other two.

    I'm going to have them try a power cycle next before going on to more troublesome steps. I found one other person reporting a similar problem that was cured by re-running guided setup, so I'll also try that if power cycling doesn't work. Then we might also try bypassing the surge suppressor, MoCA filter, and splitter one-by-one to see if something has gone bad. But I also wanted to see if anyone else had additional ideas.
     
  2. V7Goose

    V7Goose OTA ONLY and Loving It!

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    May 28, 2005
    New Mexico...
    First, do a channel scan on the TiVo to re-verify existing channels - sometimes this alone can fix a problem like this.

    Second, see if the TV that is working can show diagnostics information about the received channel - specifically, you need to verify the transmit frequency or channel number (not the display channel number).

    Now check the TiVo channel list to verify that the correct channel (verify BOTH the display channel number and transmit channel number) is available and checked. Also verify no other channel with the same number is checked.

    If you still cannot tune in the questionable stations, see if they display anything in the Antenna Signal Strength screen (which may or may not be working at all, depending on the software version currently running on that box).
     
  3. Intheswamp

    Intheswamp South Alabama

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    Nov 14, 2017
    Disclaimer...I'm not familiar with MOCA technology.

    Be sure nothing has changed regarding the channel repack. Call the stations that you're having problems with and ask them if anything has changed...antenna redirected, transmitters moved to new tower/location, power reduced, etc.,.

    Verify that the spare bedroom television is still receiving with a 72 signal strength measurement. If indeed it has a signal strength of 72 then that tells me nothing is wrong with the physical antenna, don't mess with it. Something between the antenna and the main television is robbing signal strength. There is apparently good signal strength at the antenna feedpoint.

    Beyond the stations having done something that is affecting things I would start by completely removing anything that could steal signal strength from the main television. Remove the splitter, surge suppressor, and MOCA filter, *and* TIVO Bolt (if you have a tuner in the main television). Make a "home run" connection between the antenna and main television. If the main television picks up the missing channels then start adding things back to the feed while monitoring signal strength...start by adding back in the Bolt. If reception is good with the Bolt then nothing to change/adjust/reset with it. Move on to the next piece of equipment. Etc.,.

    *Is the spare bedroom television on a shorter cable run than the main television? Longer coax cables can impact reception.
    *Is the surge suppressor protecting both televisions? Surge suppressors can go bad.

    Maybe try swapping the coax lines coming out of the splitter to see if that affects anything. Splitters seem like they shouldn't fail, but stranger things have happened...there might be a bad output port.

    Just some thoughts.
     
  4. Intheswamp

    Intheswamp South Alabama

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    Nov 14, 2017
    Two more things...

    Are there any new structures nearby that could actually be interfering with reception?

    How long has this system been in place? Years? Several months?
     
  5. LarryAtHome

    LarryAtHome Active Member

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    Feb 18, 2008

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    Recently I had problems with just one channel. It was on real channel 10. My TV did not have any issues with the channel, just the TiVo. Turned out to be LTE interference. A LTE filter solved it for me. I was not aware of any new cell towers anywhere near me.
     
  6. spatula

    spatula Member

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    Mar 31, 2014
    San Mateo,...
    Thanks for all the suggestions. Their system has only been in place a few months, and it was all working very well when I left. No new structures near where they live; they're kind of in a borderline rural area.

    I've sent them some couplers and patch cables to get them to try bypassing everything and going direct from the antenna feed to the TiVo with nothing else inline.

    My dad mentioned what he called a "loud hum" that he gets when trying to check the signal strength of one of the channels that has no signal. I don't remember the signal check screen producing any sound, especially if there's no signal lock... any ideas what he could be talking about? I'm still using an older Roamio myself, on the previous software rev, so I don't see the same things he sees.

    I'm trying to get him to hard-boot the TiVo and check the signal strength on another TV, but of course this is very difficult to do remotely.
     
  7. Jun 1, 2019 #7 of 25
    spatula

    spatula Member

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    Mar 31, 2014
    San Mateo,...
    Unfortunately, nothing seems to help with this TiVo, and I suspect the unit itself is defective. If we connect the coax from the wall directly into the TV, channel 8.1 comes in perfectly. No amount of channel rescanning, re-running guided setup, rebooting, hard booting, etc., on the TiVo manages to get channel 8 to work on this thing.

    In this case, broadcast channel # and virtual channel # are exactly the same- both are 8.

    Their TV reports a SNR of 28dB for the channel, which should be more than enough to get it tuned on the TiVo. It seems like the tuner just suddenly lost a huge amount of sensitivity.
     
    Last edited: Jun 1, 2019
  8. Jun 1, 2019 #8 of 25
    Intheswamp

    Intheswamp South Alabama

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    Nov 14, 2017
    Is there a pre-amp installed at the antenna?
    How long of a coax run is it between the Tivo and antenna?
    What model/brand antenna is installed?
    What are the call signs of channel 8 an 17?

    Sure, the television might possibly have a more sensitive receiver. But, I'm not sure whether the Tivo could suddenly stop receiving on only certain channels. Seems like a problem would affect all channels, but I'm no expert.

    Some thoughts....

    It could be that the problem channels have suddenly moved from the UHF region down to a VHF frequency and the antenna has become less effective at those frequencies (the other channels possibly still in the UHF region).

    It could be that the channels have suddenly increased their power and it's overloading the Tivo. The receiver on the television could be opposite from being more sensitive...it could be less sensitive and thus able to handle the stronger signal. Maybe even add a splitter between the coax and Tivo to create some "loss".
     
  9. Jun 1, 2019 #9 of 25
    Intheswamp

    Intheswamp South Alabama

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    Something else...have you *called* the stations and asked to speak to an engineer? They usually are glad to talk with folks to work problems out. You can find out if anything "changed" about the time the problem started.
     
  10. spatula

    spatula Member

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    Mar 31, 2014
    San Mateo,...
    Note that nothing at all has changed in their configuration, and everything has been rechecked very carefully. The station we're checking is still transmitting from the same facilities on the same channels with the same power output. The coax run is less than 100 feet of RG6-Q. There's no pre-amp as it wouldn't be necessary and it would have been counterproductive. Most of their channels are coming in with a signal strength of 72 reported on the TiVo, SNR 30, which is pretty excellent.

    The TV reports an SNR of 28 for the main channel we're troubleshooting, whereas the TiVo reports the SNR as 13. This is KPTS, 8.1 in Wichita.

    I can think of no reason for the TiVo's tuners to see such a massive drop in SNR compared to another device at the same location.

    One more thing I'm having them try is locking up a few tuners by having them record, then tuning to 8.1 to watch live. I've read of other cases where tuner 0 crapped out unexpectedly.

    I certainly can't explain why only three sets of channels were affected.
     
  11. tapokata

    tapokata Active Member

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    Apr 26, 2017
    Sacramento, CA
    I think I would call the station. 17 looks like it’s a repeater of the same channels on 8 (PBS). Both of those going out rules out an antenna issue, as 8 is a Hi-VHF station, and 17 is a low power UHF fill in for the metro area in Wichita. KAKe, the ABC affilliate broadcasts in a similar fashion, with Channel 10 and real channel 21 as the fill in. Both will display as 10.x. If they can get either of those two, I really doubt that this is a Tivo tuner or antenna problem. LTE signals are nowhere near VHF (edited from UHF) banwidths, so you can rule that out.

    Only other possibility is that the tivo channel selected in the Tivo channels setting is the lower power UHF signal, and not the VHF (or vice versa). If the locked frequency was trimmed back for maintenance, it might result in the lower signal strength and SNR.
     
  12. spatula

    spatula Member

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    8
    Mar 31, 2014
    San Mateo,...
    Why would it have anything to do with the station if we can receive it just fine by plugging the coax directly into the TV, and the TV reports an SNR of 26, while the TiVo reports an SNR of 13 for the same frequency? The TiVo is claiming to see about 1/32nd the power that the TV is seeing. At most I'd expect the TiVo to see a few dB worse SNR due to the need of amplifying and splitting amongst 6 tuners.

    We can manually tune to the translator channel on 17 (because both 8.1s appear in the channel list). It's different, but worse.

    At the same time they lost KPTS on 8.1, they also lost K15DD 15-1 on physical channel 15 (no big loss), KSMI 30 (also RF 30) and KMTW 36 (RF 35). These all come from different transmitter locations, but they all disappeared simultaneously on the TiVo, and they all still work perfectly well on a TV at the end of the same coax.
     
    Last edited: Jun 2, 2019
  13. tapokata

    tapokata Active Member

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    Apr 26, 2017
    Sacramento, CA
    Nearly any TV tuner will typically be more sensitive than the tuner array in the Bolt. Its not that the Bolt signal is “split”, as there is no additional insertion loss inside of the Bolt beyond the normal 6 to 8 dB loss associated with any tuning set. The signal to noise ratios are more a function of the Bolts internal circuitry. And I wouldn’t put too much stock in the reported SNR on the diagnostics page: if you pay attention to it, you will notice it moves directly in lockstep and dependent with changes in signal strength. As the Bolt’s AGC limits signal power readout to that magical 72, the SNR reported should be fixed at various levels while the gain is applied or reduced, not after the fact. It’s derived by assumption, not measured.

    Thanks for the info on the other channels going. Thats the first complete detail you posted here, other than “channel 8” in Kansas. With that added info, yep, quite possible the Bolt tuner has gone bad.

    The best of luck to you.
     
  14. spatula

    spatula Member

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    Mar 31, 2014
    San Mateo,...
    Unfortunately all of this information is coming to me second-hand and haphazardly from my parents, 1,350 miles away. If you think it's frustrating for you, imagine how I feel.

    Now the big trick will be convincing one of the drones in TiVo support to RMA this unit. So far all I've managed to get them to do is mindlessly regurgitate the same idiotic script to me or to ask me to do things that I've just told them I've already done.
     
  15. LarryAtHome

    LarryAtHome Active Member

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    Feb 18, 2008
    Yet it was a LTE filter that drastically improved my channel 10 reception. My CH10 reception disappeared overnight. No new towers in my area and I am at least 3 miles from a cell antenna. My Roamio continued to receive CH10 fine, just my BOLT lost CH10.
    You can always get one from a place that allows returns to try it out.
     
  16. djones18

    djones18 Active Member

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    Jan 6, 2006
    Alexandria, VA
    I read your post over in the Coffee House and understand your frustration. If the Bolt is still under warranty, I wouldn't get overly complicated explaining the problem to the CRs. I don't know how detailed your present trouble ticket is based on your conversations with TiVo.

    I've been through this before with TiVo and replaced two broken Bolts. One under warranty and one outside warranty which TiVo replaced for $50.00. I kept it simple. We're not expected to be trained technicians, diagnosticians, and I simply told them I did the basics: check all the wires, reboot, plug/unplug. Imagine you are one of your parents calling TiVo support. I would simply state the Bolt fails to now receive OTA channels when it worked fine last week. Yes, I have done the diagnostics my limited technical abilities allow and it still doesn't receive TV channels which work fine on a TV without the Bolt connected. It is clearly broken and I want it replaced. Stick to your script. Be respectful but firm. Tell them you are not satisfied if they tell you they won't do anything to assist. They will escalate the issue when pressed.
     
  17. spatula

    spatula Member

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    Mar 31, 2014
    San Mateo,...
    I'll keep after them, of course. The most recent chapter from this morning is that someone at TiVo support invented a change of frequencies in the case for the main channel we're trying to troubleshoot (KPTS, 8.1) which has certainly not changed frequency:
    upload_2019-6-2_13-14-31.png
    That was after I said in no uncertain terms that I wanted to RMA the unit because its tuner has crapped out and it's still under warranty. I really hate being lied to, and they definitely just made this up. The only station in their market that's still due for a repack is 3.1, from channel 45 to channel 15, in 2020 during phase 8.

    I think LTE is unlikely to be the culprit in this case, because they lost RF on 8, 17, 15, 30, and 35 simultaneously, and the antenna I got for them (a Winegard HD7694P) has a pair of band-pass filters as well.
     
  18. Davelnlr_

    Davelnlr_ N5GGG

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    Jan 12, 2011
    North...
    While I am no expert on Tivo, but each tuner in a Tivo will require a split. If you have two OTA tuners, that would be a 3DB loss compared to running the coax directly into the TV. If it has 4 tuners, it would be 6 db. Attic mounted antennas typically lose up to 10db going through the roof (up to 20db if the roof is metal or wet). I would highly recommend moving the antenna outside, which would probably solve all your parents problems. If that is not possible, try adding a medium gain, low noise amplifier at the antenna. As a test, bypass the 2GHz splitter. Connect the line to the Tivo directly to the Moca filter. That will add 3db to the Tivo's signal strength. If that fixes the problem, then you will need a distribution amplifier instead of the splitter.
     
    Last edited: Jun 4, 2019
  19. spatula

    spatula Member

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    Mar 31, 2014
    San Mateo,...
    This would not explain why they had no reception problems of any kind for two months, until about 2 weeks ago.

    They could even receive 8.1 with the antenna sitting on the floor in the living room when we were initially testing things out.

    Something happened. And as far as I can tell, it didn't happen to the antenna system.
     
  20. Intheswamp

    Intheswamp South Alabama

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    Nov 14, 2017
    DaveInlr_, a preamp isn't a bad idea. I know that in my rural setup that if I didn't have my Juice preamp I wouldn't have very good OTA reception. I've got probably a 70' coax run from antenna to Tivo with a splitter in the line. It's just the area that I'm in with lots of forest between us and the towers some of the signals at the antenna are just too weak to make the cable run without being amplified.

    I did a "shoot out" with the (then) new Channel Master Amplify and the AD Juice. Without a doubt the AD Juice worked best for me in my location...it's low noise I think really helped with my weak signals.
     

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