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Cisco Tuning Adapter (STA1520) Troubles

Discussion in 'TiVo Help Center' started by Pete716, Nov 4, 2018.

  1. Nov 4, 2018 #1 of 23
    Pete716

    Pete716 Member

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    Aug 28, 2018
    Buffalo, NY
    Hi all - I'm looking for suggestions from those that know more and have more experience than I do.

    I'm a Spectrum customer in a legacy TWC area (Buffalo, NY) - I'm fairly new to their tv service after years of satellite and came back to TiVO because it is a better interface and works better than anything else I've ever used.

    Anyway, the first 30 days were great - then all hell broke loose with the tuning adapter. It will work for about 8-12 hours at a time. I can power cycle it and sometimes it works again right away, other times it takes 3-4 hours to start working again.

    I've called and spoken to the Cable Card group and at this point, they believe it is a signal issue, specifically with the Return Data Carrier at this point.

    I've had 3 tech visits that have replaced pretty much every line from the pole to the TiVo and tuning adapter. They put in a zero loss splitter and ran a new line, so now both the tuning adapter and TiVO are connected directly to the splitter. After that, signal levels have improved somewhat. This is where I'm at now for signal levels in the tuning adapter diagnostics:

    Tuner: 9 dBmV
    FDC: 13 dBmV
    RDC: 5 dBmV

    The RDC seems to fluctuate and will go to 13, 17 and 20 dBmV depending on when I look at it.

    The Cable Card group told me that the signal levels should be in these ranges:

    Tuner - from -7 to +7 dBmV
    FDC - from -7 to +7 dBmV
    RDC - from +25 to +55 dBmV

    In researching, I found the Cisco diagnostic manual for the STA1520, it shows about the same, saying:
    Acceptable range for the tuner is -16 to +15 dBmV and recommended range is -8 to +8 dBmV
    Acceptable range for FDC is -16 to +15 dBmV and recommended range is -10 to +10 dBmV
    Acceptable range for RDC is +25 to +55 dBmV and recommended range is +27 to +53 dBmV

    With all that being said, the drop to the house has been replaced, the ground block in my basement has been replaced, the splitter has been replaced with a zero loss and both the TiVo and tuning adapter are on home runs to the splitter. I've also swapped out the tuning adapter with another one received at the Spectrum store. (I also have another one and another cable card on standby in case they need to be swapped again, because their techs don't carry either one on their trucks...)

    Spectrum missed their appointment with me this morning - never showed, and after 2 hours of calling them, I reached a supervisor who scheduled a QA tech to come out Tuesday evening. He also spent A LOT of time trying to convince me to get rid of the TiVo and go with their equipment, saying they have had lots of trouble with TiVo after going all digital.

    So - at this point, I'm pretty sure the issue is with the RDC signal levels, and I don't think much (anything) can be done with that in my house. What recommendations do you all have with what needs to be done and how I can proceed from here?

    (Sorry for the LONG post, but lots of info I wanted to include)
     
  2. Nov 4, 2018 #2 of 23
    dlfl

    dlfl Cranky old novice

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    You already have a better diagnostic knowledge of your TA than 99+% of users. Your FDC and RDC levels are very puzzling. FDC is a signal sent from the cable system. RDC is a signal sent from your TA back into the cable system. RDC is adjusted up or down so that your cable system gets a strong enough signal. The fact it is so low would imply very low loss on your connection, or extemely high sensitivity at the cable system receiving system. Your high FDC (and tuner) level also implies low loss (or that the signal generated by the cable system is too high). A defective TA could be the problem but if two or more TA's exhibit the same problem that is very unlikely. It has to be a problem with the cable system.
     
  3. Nov 4, 2018 #3 of 23
    kpeters59

    kpeters59 Well-Known Member

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    That high FDC makes me wonder if an Attenuator on the TA might not have a positive effect.

    -KP
     
  4. Nov 4, 2018 #4 of 23
    dlfl

    dlfl Cranky old novice

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    Dayton OH
    I agree. For example search Amazon for "cable attenuator". The Parts Express coaxial attenuators look good. Perhaps a 6 dB and a 10 dB. You can put them in series for 16 dB. Of course Spectrum should be able to figure this out and they could then furnish them.
     
  5. Nov 5, 2018 #5 of 23
    Pete716

    Pete716 Member

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    Aug 28, 2018
    Buffalo, NY
    Thanks guys, that gives me a little more info to have in my pocket when this QA tech comes out tomorrow.

    I really hope he/she is able to solve this.
     
  6. Nov 6, 2018 #6 of 23
    Pete716

    Pete716 Member

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    Aug 28, 2018
    Buffalo, NY
    So, the tech just left and you were absolutely right. He tried several different attenuators and finally this combination had the FDC at 1 dBmV and the RDC at 43 dBmV!

    For the past two weeks, when it works it’s been 8-12 hours at a time so I’m not declaring victory yet but I’m very hopeful now that the signal levels are within spec.


    BC35301F-F840-4648-A70A-D655121ABED4.jpeg
     
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  7. Nov 7, 2018 #7 of 23
    dlfl

    dlfl Cranky old novice

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    Dayton OH
    Wow that looks like four attenuators in series. What total attenuation?

    Makes me wonder if the signal into your TiVo tuners also might be too hot, or are these attenuators also reducing that signal? What are the signal strengths in TiVo diagnostics? If they are pegged at 100, that's too hot. Ideally they should be in the 90 to 95 range. Running too hot can cause video dropouts by protective circuits and over the long term can damage the tuner. (All this is per Tivo support web pages).

    The real solution here would be for Spectrum to properly adjust their system, of course. I've been monitoring TA issues in these forums for many years now and don't recall ever seeing RDC and FDC levels as far out of spec as you had.

    Did the Spectrum tech deduce the need for attenuators or did you suggest it to him?
     
    Last edited: Nov 7, 2018
    kpeters59 likes this.
  8. Nov 7, 2018 #8 of 23
    Pete716

    Pete716 Member

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    Aug 28, 2018
    Buffalo, NY
    The tech had the idea of the attenuation on his own. He actually had a bag full of them and tried a few before getting to this combination that achieved the desired results.

    I’m not entirely sure what the total attenuation is... the labels say:
    1st one: EQF4-54/860
    2nd: SSA6-54 6kV
    3rd: SSA12-54 6KV
    4th: FAM-06

    The 4th one in series has smaller print indicating it is a 6dB attenuator. The first three don’t have any other printing other than what I wrote. The first has a thin white label, the second has a wide blue label and the third a wide red label.

    I checked 5-7 different tv channels across the spectrum and most were 95% in the diagnostics. One was 92% and one was 97% the rest were all 95% I *could* move the line feeding the TiVo to the port on the splitter that has -4 dB loss (it is currently on a port with 0 loss) if that’s advisable. I certainly don’t want to damage the tuner.
     
  9. Nov 7, 2018 #9 of 23
    Pete716

    Pete716 Member

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    Aug 28, 2018
    Buffalo, NY
    The second and third in the series appear to be attenuating the upstream only so the transmit level gets increased thereby improving the signal to noise ratio.

    I’m still not sure what the first one is doing (and google hasn’t been much help so far)
     
  10. dlfl

    dlfl Cranky old novice

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    Dayton OH
    I'm guessing the first number is the dB attenuation, so you have 4+6+12+6 = 28 dB total attenuation. Don't understand "appear to be attenuating the upstream only"? However all your levels are looking really good. I'm impressed the tech figured this out, and still amazed things were so far out of spec to begin with.

    Still curious: are the attenuators affecting just the TA signals or also the TiVo tuner signals? IOW, are you using a splitter to separate the TiVo and TA inputs? And where are the attenuators inserted?
     
  11. Pete716

    Pete716 Member

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    Aug 28, 2018
    Buffalo, NY
    The attenuators are only on the line to the tuning adapter. There is a 6-10 inch cable between them and the TA coax in.

    Both the tuning adapter and the TiVo are directly connected to the main (and only) splitter which is located in my basement. One of the techs that came out ran another line thinking the 2 way splitter I had was part of the problem.

    This is the product sheet on the two attenuators that attenuate upstream only:

    http://www.tvcinc.com/shared-downloads/SSA.pdf

    It has a little more info on how those two work. Ingenious, really.

    I was absolutely thrilled that I finally had a tech that had the depth of knowledge on TiVo, cable cards and tuning adapters that he did. I had documents printed, fully expecting to have to educate the tech (as I had done with one or two of the previous ones)

    We’re at 36 hours so far. If we get to 7-10 days (I think we will) I’m going to send an email to charter to tell them this guy deserves recognition.
     
  12. dlfl

    dlfl Cranky old novice

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    Dayton OH
    Wow! Great info and I have learned something for sure.

    I noticed it looked like you needed more attenuation for RDC than for FDC.
    The FDC and RDC frequencies are listed in your TA diagnostics and on my system RDC has been either 10.0 MHz or 16.5 MHz (it changed recently) while FDC is always 74.0 MHz. It looks like you have 3 step attenuators with cutoff at 54 MHz and that is exactly what would give you huge upstream-only (RDC) attenuation, 22 dB assuming the first 3 models you listed are step attenuators.

    I agree your tech needs commendation. Must be one in a thousand IMO.

    I wonder what causes this upstream/downstream imbalance? Cable attenuation per foot does vary with frequency but not enough to cause 22 dB difference between those two frequencies.
     
  13. Pete716

    Pete716 Member

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    Aug 28, 2018
    Buffalo, NY
    My RDC is at 10 MHz and FDC at 74 MHz. I was kind of surprised they go as low as 10 MHz, but I guess they need to use every bit of spectrum they can.

    He seemed to think some plant maintenance was in order to truly correct the signal issues, but he was hesitant to request that right away as then the attenuator setup would need to be adjusted or possibly eliminated. He suspected there was too much noise at 10 MHz and they needed to 'clean it up' This makes sense, as now after attenuation, the upstream signal is louder giving a better signal to noise ratio.

    He did leave me with his email address and asked to know one way or another what happens so he can request maintenance or know that it's working well.
     
  14. Pete716

    Pete716 Member

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    Aug 28, 2018
    Buffalo, NY
    ...and today the SDV channels aren’t working again and RDC has been all over the place between 1 and 43 (mostly 1, 17, 20) even after a full reboot of the tuning adapter.

    I emailed the last tech letting him know and also called in, cable card support wants to do another tech visit (5th in 20 days) Still hoping to get to the bottom of this so I can have reliable service.
     
  15. kpeters59

    kpeters59 Well-Known Member

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    Has it rained since the last visit?

    Maybe a leaky connector outside...

    -KP
     
  16. Pete716

    Pete716 Member

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    Aug 28, 2018
    Buffalo, NY
    It’s definitely rained (and even a little snow) - It’s a single cable from the pole into the ground block in my basement (and then to the splitter) when that was replaced, the tech could have left something loose at the tap.
     
  17. kpeters59

    kpeters59 Well-Known Member

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    Any chance he already replaced the fittings at either end of the 'drop'? Or replaced the drop?

    -KP
     
  18. Pete716

    Pete716 Member

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    Aug 28, 2018
    Buffalo, NY
    He replaced the entire drop from the pole into the basement.
     
  19. kpeters59

    kpeters59 Well-Known Member

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    Well, that doesn't mean it couldn't be a connection further back down the line.

    I'd see if they might not be able to check signals at some of the neighbors equipment.

    -KP
     
  20. Pete716

    Pete716 Member

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    Aug 28, 2018
    Buffalo, NY
    I tried to ask them about signal levels of neighbors but they shut that idea down and just want to send another tech out (basically beating a dead horse at this point) - my tech from last week did reply to my email and tell me he asked his manager to submit it to the team that does plant maintenance to clean up those frequencies.

    I'm a little hopeful, but I know better than to hold my breath for anything.
     
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