[mythtv-users] Tuner Failure

[Jay Foster]

I recently experienced a tuner failure, or what mythtv interpreted as a 
tuner failure, and am looking for some information to help explain the 
behavior of mythtv under such circumstances.

I have a combined FE/BE system with 3 HDHR (6 tuners).  A couple of 
weeks ago, I noticed some really bad corrupted recordings.  I confirmed 
that the recordings were all from the tuners using the first HDHR 
(tuner1, tuner2).  I suspected a HDHR power supply issue, and confirmed 
this using the hdhomerun_config_gui application to check each tuner.  I 
did not have any more spare power supplies, so noticed that there were 
no upcoming scheduled recordings using tuner5 or tuner6 (HDHR #3) for 
the next 10 days, so I unplugged the power supply from HDHR #3 and 
plugged it into HDHR #1 and ordered some replacement power supplies.

This left HDHR #3 (tuner5 and tuner6) powered off for about a week. When 
the new power supplies arrived, I reconnected HDHR #3 and tested all of 
the tuners again using the hdhomerun_config_gui application.

Last night, was the first scheduled recording using tuner5, and it 
failed (B recording).  Oddly, mythtv attempted to record this program 
twice at the same time on both tuner5 and tuner6, both of which failed 
(same HDHR).  I retested the tuners using the hdhomerun_config_gui 
application and they are still working fine.  I tried using the mythtv 
watch tv to see if it was just mythtv having a problem using tuner5 and 
tuner6, but I could not determine which tuner live TV was using.  I 
tried using the Y key to switch tuners, but the OSD does not tell me 
which tuner is selected.

I rebooted the FE/BE, and scheduled some test recordings using tuner4, 
tuner5, and tuner6 at the same time.  These appear to be working properly.

Some questions about the behavior of mythtv.
1) How quickly does/can mythtv detect a tuner failure when starting a 
recording and schedule the same recording on another tuner?  I did not 
think mythtv did this, only rescheduling at a later time, not the same time.
2) Did having tuner5 and tuner6 powered off for about a week somehow 
inform mythtv that these tuners were not working?  If so, why did mythtv 
not determine that they were working again when tuner5 and tuner6 were 
powered back on?  I thought that mythtv only queried the tuners when 
attempting a recording.
3) Is there some process, other than rebooting, that needs to be done if 
a tuner is taken offline for a while and then put back online later?

Jay