# Bolt pixilation problem solved - for the moment



## Roger45 (Dec 19, 2018)

I spent 6 weeks blundering about with this problem. I hope this account helps somebody avoid the same frustration.

Cable: Comcast Houston
In home distribution: POE filter, 4 way splitter of incoming signal. No further splitters in the system.
Equipment : Tivo Bolt
Symptom: Pixilation on almost all live TV channels. Some had no signal at all. Problem varied marginally over time, but generally unwatchable. Same on all tuners. Signal strength 65-70%.

Actions:

This is roughly the path we took over numerous calls to Tivo help, Comcast help and 6 comcast technician visits.

1. Replaced cable cards over 5 times

2. Replaced drop from utility pole to house, POE filter, splitter, cables, and connections.

3. Installed amplified splitter. 

4. Replaced Bolt. 

None of this helped. At this point Bolt signal strength was 67% SNR 27dB. Also, I have a Tivo Premier. It worked fine with the Bolt's connections (coax, cable card, TV and ethernet). Premier signal strength 96% SNR 37dB. Also an Xfinity X1 DVR worked fine with the same connections (except the cable card).

5. About to give up. Tivo help were constantly advising the Bolt required a signal strength of over 80% and SNR 30-36dB. Escalated, and they initiated a 3 way conversation with Comcast Tivo help. Comcast adamant the pixilation caused by insufficient signal strength and also diagnosed a line problem within 85ft upstream of the house.

6. Measured signal at modem: downstream signal power 13 dBmV SNR 40 dB, upstream signal power 37dBmV

7. Comcast supervisor technician arrived after a day or so. Measured signal at modem: downstream power 11 dBmV SNR 37 db, upstream power 37 dBmV. Removed inlet amplified splitter and installed 5 way splitter. Measured signal at modem: downstream power 6 dBmV SNR 40 db, upstream signal power 44 dBmV. Tested a variety of additional splitters just upstream of the Bolt, to optimize Bolt signal. Settled on 7dB loss at splitter. Bolt signal strength 77% SNR 30dB, no pixilation.

Final thoughts

The current signal strength is not ideal, but improved and I have no pixilation.

I read in an online thread that upstream signal strength must be greater than downstream SNR for the Bolt to work. 

It appears that Comcast adjusted the incoming signal to some extent upstream of the house. The Comcast supervisor technician then balanced the downstream and upstream signal at the Bolt. Comcast also refunded the temporary X1 rental and cable card rentals!

The first escalation to the Tivo help supervisor resulted in a new Bolt. The second escalation resulted in the 3 way conversation that, along with the length of the problem log, seemed to spur some action. Prior calls to Tivo help ended up with a recommendation for somebody else to do something: replace cables; remove splitter; amplify signal, attenuate signal. It would have helped to provide downstream signal requirements in units the technician could measure, so that we knew what to aim for. And if there is a criterion for upstream signal strength, it would be helpful to know what it is.


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## Roger45 (Dec 19, 2018)

Bolt Pixilation - Take 2
The saga continued. After 2 months the Bolt pixelation returned with a vengeance. The signal arriving at the Bolt was:
downstream power 5dBmv
downstream SNR 41 db
upstream power 45 dBmv
upstream SNR 32 dB

The Premier and the Bolt rquired an additional 3.5 dB drop across a splitter and then recorded (from the same outlet)
Bolt signal strength 77% SNR 31dB
Premier signal strength 93% SNR 37dB

Called up Tivo and almost immediately they offered me another Bolt. This was the 3rd I received (the second replacement). When this one arrived it was newly manufactured. The previous replacement was 18 months old and refurbished. The new one worked perfectly out of the box measuring similar signal strength and SNR to the premier.

So now I wonder if the original Bolt overheated when it was in a cabinet.
Then the second refurbished Bolt lasted a couple of months on top of the cabinet (ODT 64 deg C), but either wasn't well refurbished or overheated or both.
The third is on bottle caps on top of the cabinet with a 5" AC Infinity fan on continuously (ODT 57 deg C) in a room at 70 deg F and I'm keeping my fingers crossed.


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## hankuro (Nov 7, 2009)

Roger45 said:


> Bolt Pixilation - Take 2
> The saga continued. After 2 months the Bolt pixelation returned with a vengeance. The signal arriving at the Bolt was:
> downstream power 5dBmv
> downstream SNR 41 db
> ...


Best of luck with no future pixelation. You deserve it! I admire your perseverance. It might motivate me to get back on trying to work this through in my system. I'm with Cablevision/Optimum on Long Island, NY.

I too have been through multiple cable cards and multiple Bolts and still have pixelation. Mine occurs as intermittent horizontal zigzag lines. But I've given up multiple times. It's just too time consuming and gut wrenching. Incompetent or inexperienced tech support, hold times, having to go through ridiculous exercises that I know go nowhere.

My only good solution has been to watch less and less cable TV and watch apps instead.

How confident are you that the TIVO advised 80db signal strength and 30-36db SNR are worthy goals?

Do you get the downstream and upstream values from the diagnostic screen?

Still don't know if I want to go through this again. But for some perverse reason, I still love TIVO.


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## jefny (Feb 13, 2008)

Some years ago I had a serious pixelation problem using a tivohd and the problem was that the signal was too strong according to the FIOS technician. I should mention that I previously had Cablevision whose technicians had all sorts of problems with Tivo and Cable cards while Verizon techs seemed much more conversant with Tivo and I was able to install the cable cards myself. Anyway, I then used coaxial cable attachments called attenuators that come in various strengths of attenuation and can be plugged into one another at the point that the tivo connects to the cable company's coaxial in. It cleared up the problem. I am using the same attenuators for the bolt that I had upgraded to and the results have been good.

JohnF


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## Roger45 (Dec 19, 2018)

hankuro said:


> Best of luck with no future pixelation. You deserve it! I admire your perseverance. It might motivate me to get back on trying to work this through in my system. I'm with Cablevision/Optimum on Long Island, NY.
> 
> I too have been through multiple cable cards and multiple Bolts and still have pixelation. Mine occurs as intermittent horizontal zigzag lines. But I've given up multiple times. It's just too time consuming and gut wrenching. Incompetent or inexperienced tech support, hold times, having to go through ridiculous exercises that I know go nowhere.
> 
> ...


I believe the signal strength and SNR are good starting points. The problem is that quoting signal strenth in % is useless to any outside agency because everybody else uses dBmv. In addition, as I mentioned above, my Bolt with pixelation measured 77%, then the latest one measured 93% from the same signal, as did the premier. That is why I posted the signal parameters from all sources for comparison. Comcast kept telling me my signal was good and it seems they were correct.

I got the downstream and upstream values by logging on to my modem, except for the upstream SNR which is not listed. When ever I called up Comcast for help I asked them to give me a reading of the signal which arrived at the house. They provided all the upstream and downstream values, which checked out pretty well.

The advice I received mostly centered around signal, cable hardware and cable card. I can only add that next I would look for the manufacture date of the Bolt and the operating temperature, which is ODT in Help / Account & System Info / System Information


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## Roger45 (Dec 19, 2018)

jefny said:


> Some years ago I had a serious pixelation problem using a tivohd and the problem was that the signal was too strong according to the FIOS technician. I should mention that I previously had Cablevision whose technicians had all sorts of problems with Tivo and Cable cards while Verizon techs seemed much more conversant with Tivo and I was able to install the cable cards myself. Anyway, I then used coaxial cable attachments called attenuators that come in various strengths of attenuation and can be plugged into one another at the point that the tivo connects to the cable company's coaxial in. It cleared up the problem. I am using the same attenuators for the bolt that I had upgraded to and the results have been good.
> 
> JohnF


Yes, I have the same problem and attenuate the signal using a splitter. Here are some readings I took.

Attenuation Signal Stength SNR
(dB) % dB
0 0 0
-3.5 93 37
-7 90 37
-10.5 89 37
-14 0 0


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## Roger45 (Dec 19, 2018)

Roger45 said:


> Yes, I have the same problem and attenuate the signal using a splitter. Here are some readings I took.
> 
> Attenuation Signal Stength SNR
> (dB) % dB
> ...


The formatting did not come out too well, but -3.5dB attenuation is the sweet spot in my application.


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