[TWC] Channel Unavailable: Cisco 4742HDC & Samsung SMT-H3260 box
I've just run into an odd problem and eventually solved it. Wanted to pass it along in case someone else has the problem. I've discovered these two brands of cable boxes apparently fight if on the same drop amplifier.
I had 3 Samsung SMT-H3260 cable boxes for a couple of years. One eventually failed and was swapped with the latest and greatest thing from Time Warner, a Cisco 4742HDC cable box. The local office no longer had Samsung boxes, they said.
I then started getting random "channel not available try again later" messages on the high def channels on the Cisco over the next few days. Tried replacing a splice in the box feed coax, no effect. Then TW sent a tech out who changed the coax connector at the box. He found it was not getting an IP from the cable network and was in "one-way mode" (had great signal levels in both directions) but that stopped while he was here. Problem continued the following day.
Swapped box again for another Cisco 4742HDC at TW's phone support request. No effect. Another tech came out and swapped the ports on the drop amp (A 9 port Evolution EVO1-9-U/U that amplifies 0dB both downsteam AND 0dB upstream, plus 3db passive voice modem port built in) between the problem box and one of the working Samsung boxes and replaced the coax connector on the amp end on the "problem" wire.
The new box failed shortly after the tech left (failed to recognize its cable card). On a subsequent phone call with TW support moved one of the (working) Samsung boxes in the location where the Cisco wasn't working. That worked, which ruled out the wire, connections, and port as the problem. Next business day (was a weekend) swaped the dead Cisco with a new one and now that started having the problem. But it was in a different location, since the tech had swapped the ports on the amp, so it appeared that a Cisco 4742HDC *anywhere* on the network with the 2 Samsung SMT-H3260 boxes was having the random "channel not availble" problem.
At that point I swapped out both remaining Samsung boxes for Ciscos so that the only thing on the system would be the 3 Cisco 4742HDC boxes. Worked! Has been working perfectly for 5 days now. Not one single instance of "channel not available" on any of the 3 boxes.
I have no idea why the Cisco and Samsung boxes were fighting, or why the Samsung boxes were apparently "winning", but I suspect something to do with MoCA. I'm not using MoCA (in house AV networking over the house coax wires) but the new Cisco 4742s are apparently MoCA capabe/enabled while the Samsungs are not from what I can tell.
MoCA is supposed to be way up past the 850mHz cable band at 1150mHz, so I don't see the connection, but apparently MoCA has to put out a lot of power to work output-to-output on splitters and amps. Maybe that was overloading the Evolution drop amp given that particular amp amplifies all 8 video ports upsteam (0dB) as well as down. Or maybe nonlinearities in the amp were causing harmonics when the high power MoCA stuff was forced through the trailing edge of the filter curve (the Evolution is rated to just 1Ghz from what I can tell and I'm assuming the MoCA is at 1150mHz).
Anyway, bottom line, if your new Cisco 4742HDC from Time Warner is having "channel not available try again later" problems on the high def (100's) channels and you have other brands of cable boxes on your system, try swapping your system over to ALL Cisco 4742HDC boxes and see if that fixes it. Worked for me.
EDIT 12/13/2012. The more I read up on it all the odder things get. Apparently MoCA blocking filters on the drop cable entry to the drop amp (Point Of Entry) are a necessity to keep the MoCA stuff out of the neighbors. Just like the internet "network neighborhood" in Windows netBIOS boondoggle 15 years ago when cable first rolled out internet. Not sure I understand why they are passing out MoCA enabled cable boxes when there are no MoCA filters on the existing drop amp and none available at the TW office. At one Time Warner local office today the folks there had not even heard of MoCA. At another they said I would have to sign up for the $200 signature home to get a MoCA filter put on the POE by them. What?? Maybe MoCA is not turned on in the Cisco boxes when they hand them out.
Then I find out just now in a posting that TW may be using switched video for some of the regular channels. I knew that is how the on-demand stuff worked, but it is inconceivable to me that switched video would be used for the regular HD programming. There would be no guaranteed delivery with that setup, which is OK for on-demand but would be a poor design for regular programming it seems. If so that could certainly be the origin of the "channel not available try later" message. Switched video would also explain the fairly long delay I've always had on channel changing on any brand of the Time Warner cable boxes over the last few years.
Switched video would leave 3 causes that I can see. (1) Samsung boxes somehow blocking the Cisco boxes from sending the channel request upstream, (2) no uncommitted channels actually available on the pole hardline, which can't be the problem since the problem went away when I switched to Cisco 4742HDC's for all 3 boxes or (3) the Samsung boxes were somehow blocking the downstream SDV signal from being delivered to the Cisco. And somehow the MoCA in the Cisco boxes may be involved. Curious stuff...
EDIT 12/15/2012. Well so much for my theory that MoCA is causing the problem. After nearly 3 hours of internet searching I finally figured out how to access the ODN diagnostic screens on the 4742HDC via the remote control (this box has not buttons at all on the front other than power). On screen 23/35 in the mfgr diagnostics it shows MoCA as disabled, along with the ethernet home networking port. That at least explains why TW wasn't handing out MoCA POE filters with these boxes.
So I'm back to having no idea whatsoever as to why the Cisco 4742HDC and the two Samsung SMT-H3260s were fighting. But 7 days now and all three sets/boxes are working perfectly with everything switched over to the Cisco 4742HDC boxes. Not one single instance of "channel not available try again later".