1 of 2 active tuners goes blank/dead - reproducible DCX-3510 problem

Discussion created by bcb on May 7, 2014
Latest reply on May 10, 2014 by bcb

This is a frustrating problem with my 3510 that's been bothering me for many months. Only now have I been able to reproduce it semi-reliably, so before now I haven't reported it. I'm willing to bet money there's some bug in the way the 2 tuners buffer live TV.


In summary: occasionally 1 of th 2 tuners in active use in the DCX-3510 suddenly goes blank - no video, no audio, however you still see the quick menubar at bottom of the screen when you first switch to that tuner (so it's clear you have actually changed the channel).


This typically happens when switching back and forth between tuners (e.g. flipping between watching 2 shows) shortly after setting or canceling a manual recording in the guide for an upcoming timeslot. The tuner that goes blank stays stuck in this blank/dead state until you change channels to a 3rd channel you weren't flipping between previously.


below I'll describe ONE possible way to cause 1 tuner to get stuck in this blank state - however it's important to note that it doesn't always happen when you follow this particular sequence of commands, however it IS quite repeatable. In trying to figure out what sequence causes this condition in the past couple days, I've managed to repeat this blank/dead tuner state dozens of times (and yes before you ask, I have rebooted my 3510 and can thereafter still reproduce this problem).  Sometimes, a slightly different sequence of similar commands may also trigger the blank/dead state. Sometimes the blank/dead tuner condition can be repeated several times in a row, sometimes it takes several tries before it happens. Sometimes I can repeat the problem on a pair of channels several times in a row and then I cannot repeat again until I try it on another pair of channels. It's very strange, but perhaps these are all clues.


So the behaviour isn't 100% consistent, but as I said, the problem CAN be reproduced. 


this is a sequence of commands that I've discovered will quite often trigger the problem:


1) press Pwr to turn the 3510 on. let's call the currently showing live TV channel, "Channel A"

2) Open the Guide. Select the current show in a adjacent channel, let's call it "Channel B". Live TV now is showing Channel B

3) Open the Guide. Select a show on Channel A in the next timeslot (e.g. 1 hour from now). SET a recording for that show

4) while still in the Guide, now select the current timeslot/show on Channel A - live TV from Ch A is now displayed

5) Open the Guide. select the recording you just set on Ch A, then Change Recording Options/CANCEL the Recording

6) while still in the Guide, now select the current timeslot/show on Channel B - live TV from Ch B is now displayed

7) Open the Guide. now select the current timeslot/show on Channel A ---> instead of live TV, Channel A is now blank/dead !!!


at this point, you can switch back and forth between Ch A and Ch B, but only Ch B displays normally and Ch A remains dead.

Channel A only returns to normal if you first switch to another channel (e.g Channel C) then back to A and/or B.


sometimes, the tuner will go dead at step #6, or as I mentioned with a slightly different sequence of events. The common things seem to be switching back and forth between 2 tuners and in between setting and/or canceling a recording in an upcoming timeslot. This has happened to me many times in real-life TV watching situations (e.g. flipping between 2 different hockey games, sometimes 1 feed goes blank/dead if I go to set/cancel some other recording).


theory & observations:

- I assume that after step #2 described above that both of the 3510's tuners are alive and actively buffering the 2 live TV shows (to allow pausing/FF/REW of live TV on both channels).  My theory is that somehow setting then canceling a future recording on one of the active channels somehow screws up the buffering of one of the tuners?  Note that the tuner that failed and the set/canceled recording were both on the same channel (Ch A). Anyhow, whatever the cause, there's something odd going on here with the live TV buffering, I think - and I don't see why setting/canceling a future recording should affect the tuners and/or buffers, but it seems to do so. And I guess the reason the blank/dead state is finally cleared when you tune to Channel C is because this forces one of the tuners to now start buffering the newly selected channel and the stuck channel resumes correct buffering & display


I have a short 1min video clip of the above sequence triggering the problem, if you need, but I believe if you try the sequence above enough times you can cause the failure. important - remember I said the behaviour is not consistent so it may take a number of trials to reproduce. i.e. Shaw don't pass this off as a "one-of" problem if you try to reproduce once and cannot...


I hope that this problem gets some attention and doesn't disappear into the depths of this forum as have some of the other outstanding issues...