[mythtv-users] DVB-S locking problem

[Lawrence Rust]

On Sat, 2011-12-03 at 20:07 +1100, Mark Carbonaro wrote:
> Hi,
> 
> I have a strange issue that started happening in the last month and
> was wondering if anyone has some advice on how I can track down and
> resolve the issue.
> 
> I use a DVB-S (Tevii S660) which was working fine, but all of a sudden
> it stopped getting a lock (Tl___).  I thought I may have blown the
> tuner or something like that so I grabbed a PCI DVB-S tuner that I
> had, but the same problem.  I connected my providers decoder back in
> and it works fine (so the dish, cabling, LNB and smart card seem to be
> fine).
> 
> Thinking it may have been my Gentoo install I tried installing Arch
> Linux (quicker than re-doing Gentoo from scratch), but the same
> problem remained. In the end I reinstalled Gentoo from scratch, double
> checked all the config, kernel etc, but still no locks.  I tried
> running dvbscan and szap but again no transponders tuned and no locks.
> 
> This is where it gets strange, if I stop mythbackend and power cycle
> the S660 (its a USB external tuner) without rebooting the computer.  I
> can run dvbscan and szap without issue.  dvbscan finds all the
> channels and szap happily tunes and locks the channels.  If I then
> start mythbackend, I can't lock channels and running dvscan/szap fails
> until I power cycle the device.  Running a channel (scan all
> transports) from mythtv-setup times out trying to tune all transports
> regardless if I have power cycled the device or not.  It seems
> everytime a mythtv component touches the tuner it kills it.
> 
> I am running the following:
> mythbackend version: fixes/0.24 [v0.24.1-101-g5da2367]
> Linux Kernel Gentoo 3.0.6 (I have also tried running 2.6.39 kernel as
> it seemed to stop working around the time I upgraded, but no luck)
> 
> I would appreciate any help you are able to provide trying to figure
> this one out as its got me stumped.

I had a similar problem a while back with a tbs6981 dvb-s2 card.  With
certain makes of LNB, sending a DiSEqC command burst would cause the LNB
to lock-up.  The LNB then needed to be disconnected to be reset.  I
found that if I disabled the DiSEqC message then all was OK.  In the end
I bought a different make of LNB and that solved the problem.

Maybe you have a DiSEqC switch or something that's misbehaving?  Or
maybe you have Myth setup to use DiSEqC?

-- 
Lawrence