[pvrusb2] Tuner problems

[Mike Isely]

On Sat, 2 Apr 2011, Jim Peters wrote:

> My backend has 6 tuners a pvr150 a pvr350 and 4 wintv pvr usb tuners. I am 
> having problems with 2 of the wintv pvr tuners. 

> 1 of them just quits/dies on me, it records blank videos when this happens (0 
> byte files)when this happens I just reboot the backend and everything works fine 
> again for a while (I have actually made a cron job that runs every 4 hours to 
> reboot the server if no recordings/comflaging/mediawatching is going on) this 
> is a temporary fix that doesn't work well because I still get quite a few blank 
> recordings from this tuner, so I would like to fix it. 

Only 1 fails while the other continues to work?  Obviously software 
isn't going to differentiate this unless the models are different.

My experience in cases like this is that either you're running a 
*really* old driver (like something from 2006) or the hardware is simply 
flaking out.  Assuming that you're running a relatively recent kernel 
(and thus a recent driver), then possible hardware issues might be:

1. Bad USB cable, hub, or port - USB works perfectly when it works, but 
noise or marginal wiring can *really* foul things up.  I've been down 
this road many times, unfortunately.

2. Dirty power - your PC benefits from a huge internal power supply that 
can bridge all manner of power line abuse.  All your internal devices 
(e.g. pvr150, pvr350) benefit from this.  But your external tuners are 
powered from little wall-warts that simply can't defend against power 
spikes / glitches / sags.  This can cause the tuner to crash.

3. Heat problems - the mpeg encoder in these tuners uses enough power to 
get fairly warm.  This is why you never see these devices for sale in a 
USB cable-powered configuration - there just isn't enough juice 
available.  But that power creates heat, and while these devices are 
pretty forgiving, it *is* possible to overheat one.  If you have the two 
devices stacked for example, the one on the top is going to be in the 
convective heat flow coming from the bottom tuner, so it will run 
warmer.  I learned of a story once where one person stacked four of 
these in an enclosed box and experienced a lot of crashes...

Since you have 2 tuners, you have a tremendous advantage.  Try swapping 
them.  Does the problem stick with the specific tuner?  Could one be 
lacking ventilation?  Try swapping power bricks between them.  This 
should allow you to quickly zero in on the specific piece of suspect 
hardware...


> The other one has a screen flickering problem, it will flicker badly for a 
> couple minutes then clear up for a few seconds and flicker some more. It looks 
> somewhat like the old horizontal roll of old (really telling my age now!) but 
> with digital attributes (chunks of the picture in the wrong place and stuff) I 
> have this tuner set as the last tuner in the system so it hasn't been a big 
> problem but between my wife learning how to use mythtv for her stuff, and an 
> increased recording schedule on my part, it was the tuner that was used for 
> stargate universe last week..... so now we have a problem that needs fixed! 
> Anyway my big problem is that I have no clue as to where to start looking for 
> answers for these problems. what log files to look at or any special debugging 
> steps i can take to get info that might be useful to figure this out. any help 
> would be appreciated. Thanks

That sounds like a weak signal.  Are both PVR-USB2 tuners doing this or 
just one?  Which model is this?  (24xxx, 29xxx, HVR-1950/1900)  If these 
are HVR-19x0 devices, then are you having the problems in digital or 
analog mode?  If you rip from a VCR or DVD player (using the composite 
or s-video inputs) do you still see the flicker happening?

  -Mike

-- 

Mike Isely
isely @ isely (dot) net
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