I’m hoping someone here might have an idea before I give up on my 4th-generation Tablo and replace it with another OTA DVR/tuner.
The problem involves KOATCBS 7.4 in Silver City, New Mexico (ZIP 88061). This is the new CBS service recently added to KOAT.
The problem
The Tablo channel scan finds KOATCBS 7.4, identifies it correctly, and shows full/excellent signal strength. The scan identifies it as 720p.
However, selecting 7.4 results in a playback error stating the following “Failed to load. A network error occurred. An unrecognized error occurred.” and the channel will not play.
This ONLY happens with 7.4. All of the other OTA channels work normally.
Importantly, KOAT 7.1 works perfectly and shows full signal strength. My understanding is that 7.1 and 7.4 are both carried on the same physical RF channel/multiplex from the same KOAT Silver City transmitter.
Interesting history
When this CBS channel was first added, 7.4 actually DID play through the Tablo.
The initial problem was that the Tablo guide information for the new channel wasn’t populated.
After going through rescans/guide updates/etc. trying to correct the guide, the guide information eventually became correct — but then 7.4 stopped playing and began producing the playback error.
I have not been able to get it to play since.
Troubleshooting performed
I have tried all of the following:
- Rebooted the Tablo multiple times.
- Completely power-cycled the Tablo.
- Rebooted the streaming devices.
- Confirmed the Tablo is running the current firmware.
- Removed/deselected 7.4 from the channel lineup.
- Saved the lineup with 7.4 removed.
- Updated the guide.
- Performed a fresh channel scan.
- Re-added 7.4.
- Saved the new lineup.
- Updated the guide again.
- Repeated the remove/save/rescan/re-add process multiple times.
- Tested with the Tablo’s built-in antenna amplifier enabled.
- Tested with the Tablo’s built-in antenna amplifier disabled.
- Tested playback through two Onn Google TV/Android TV streaming devices.
- Tested playback through the Tablo iPhone app.
- Tried recording programming from 7.4. Recording fails as well.
- Enabled Audio Compatibility Mode after the iPhone app specifically suggested doing so.
- With Audio Compatibility Mode enabled, I initially got a different behavior where 7.4 did not immediately produce the playback error but simply sat there trying to load indefinitely.
- After that initial attempt, it returned to producing the normal playback error.
- With Audio Compatibility Mode still enabled, I again removed 7.4, saved the lineup, updated the guide, rescanned, re-added 7.4 and updated the guide. It still does not work.
- Performed a complete factory reset of the 4th-generation Tablo and set it up again from scratch. The problem remains.
- I have also tried changing zip codes in the channel setup but this also did not result in a change in behavior.
Direct TV tuner test
This is probably the most important troubleshooting result.
I disconnected the Tablo from the equation and connected an OTA antenna directly to a television.
After scanning for channels on the TV:
KOATCBS 7.4 played normally.
All of the other channels worked as well.
The antenna I used for this test was actually the small indoor antenna that came with the Tablo, in a less-than-ideal temporary location.
I then took that same Tablo-supplied antenna that successfully received 7.4 on the television and connected it directly to the Tablo.
After rescanning:
7.4 still produced the playback error on the Tablo.
So the same antenna can receive and play KOATCBS 7.4 when connected directly to a television, but the Tablo cannot play 7.4 from it.
Outdoor antenna / signal testing
The Tablo is normally connected to an Onn outdoor OTA antenna.
I initially wondered whether its amplifier, excessive signal strength, multipath, or antenna direction could be responsible.
However:
- Tablo’s internal amplifier has been tested both ON and OFF.
- The separate Tablo indoor antenna was also tested as described above, with the same failure.
- The outdoor antenna is already pointed directly toward the transmitter site.
- KOAT 7.1 (An ABC affiliate) shows full signal strength and plays flawlessly.
- KOATCBS 7.4 also shows excellent/full signal strength during the Tablo channel scan.
Therefore this doesn’t appear to be a simple weak-signal or antenna-aiming issue.
What makes this particularly strange
The combination of symptoms is:
KOAT 7.1: Full signal, works perfectly
KOATCBS 7.4: Full signal, detected correctly, will not play or record
7.4 connected directly to TV: Works normally
Same antenna connected to Tablo: 7.4 fails
Other Tablo OTA channels: Work normally
Factory-reset Tablo: 7.4 still fails
Multiple Tablo client devices: Same failure
And again, 7.4 initially worked on this Tablo before the guide/channel-lineup troubleshooting was performed.
Tablo support
I have also been working with Tablo support.
Unfortunately, both phone and email support have mostly continued suggesting basic troubleshooting steps that I had already performed and described to them. I have asked for the issue to be escalated and for someone to examine the Tablo’s diagnostic logs, but so far I haven’t received any useful technical explanation.
What I’m wondering
Has anyone encountered a situation where one specific subchannel within an otherwise-working OTA multiplex is detected at full strength but cannot be played or recorded by a 4th-gen Tablo, while a normal television tuner plays that same subchannel without a problem?
I’m particularly wondering about:
- MPEG-2/MPEG-4 or other codec compatibility
- AC3/audio stream issues
- PMT/PID/PSIP or transport-stream differences
- Some unusual encoding parameter on the new 7.4 CBS feed
- A Tablo firmware bug involving this particular stream
- Stale/incorrect guide or station metadata, especially since 7.4 originally played before the guide information was corrected
- Anything else specific to newly added OTA subchannels
At this point I believe I have exhausted the normal antenna, signal, rescan, guide, app, reboot and factory-reset troubleshooting.
I’m considering replacing the Tablo with an HDHomeRun FLEX DUO, but I’d really prefer to get the Tablo working if someone here recognizes these symptoms or knows of another diagnostic/fix I can try.
Any ideas — particularly from anyone familiar with the technical side of the 4th-generation Tablo tuner/playback system — would be greatly appreciated.
