[mythtv-users] Two mysteries

[Stephen Worthington]

On Sun, 28 Apr 2013 10:21:27 -0700 (PDT), you wrote:

>Hi folks,
>In the face of plummeting WAF and rising frustrations I'm appealing to you to help me solve two mysteries plaguing my mythtv.
>
>First the background:
>My recently retired mythbox ran for several years with excellent reliability.  I have all my AV gear in another room and I control it all with a wired IR repeater (the Xantech dinky link).  I was using an MCE remote receiver (the big blocky one that came with a model 1039) and everything worked fine.  However, I was looking to add more storage and my case was already bursting so I decided it was time for an upgrade.  I chose a mini-ITX motherboard (DQ77KB) with a DC power input from an laptop style brick.  
>
>I finished my build and plugged in the MCE remote receiver but it didn't work.  The little LED on the MCE receiver said that it was seeing button presses but they weren't being relayed to the OS.  I tried several different things with LIRC but concluded that somehow the USB3 ports wouldn't work with this ancient remote receiver (possibly incorrect conclusion).  My old box was running ubuntu 10.04 with mythtv 0.24 while the new one was ubuntu 12.04 with 0.25.  What also happened when I plugged in the new mythbox is that my dinky link was registering button presses randomly as if there was a remote being pressed randomly.  I discovered later that the new mythbox was causing the spurious signals, whenever I powered off the new mythbox the dinky link stopped seeing bogus signals.  About a week after I converted my old mythbox into a remote frontend with the new machine as master backend/FE the old machine died.  So now I have a FE/BE machine with not
> remote control (except mythmote android app) and a little LED on the dinky link that flashes randomly 24/7.  Both together are sinking the WAF.
>
>Mystery #1:
>With my new mythtv box turned on but disconnected from HDMI and ethernet (so the only cord attached is the DC power cord) my dinky link IR repeater is firing randomly.  It is worse when I'm playing back content and seems to be quieter when the mythbox is idle.  I thought electro-magnetic noise might be coupling from the new mythtbox into the dinky link.  So I tried wrapping the dinky unit in tin foil but that didn't help.  Then I wrapped the AC/DC power brick and my network switch in tin foil but it didn't help.  So now I'm thinking that somehow the mythbox is putting a ton of noise onto the AC lines and that's how it is messing up the IR repeater.  

My experience with my IR repeater is that it can get signals from
unexpected places.  Like a TV screen, or fluorescent lighting.  I am
afraid it is many years since I was last using it, so I do not
remember exactly what I worked out was triggering mine, but I do know
that it caused symptoms just like what you are describing, and I had
to shift its placement to avoid the signal.  So, have you checked
whether it is triggering from an environmental IR signal instead of
electrical noise, by shielding the receiver hole?  I just used to cup
my hands around the receiver and move them in and out and around to
try to work out what direction the spurious signal was coming from.

>Mystery #2:
>Based on the failure of my MCE receiver I bought a FLIRC IR receiver.  However when I plug it in to the mythbox it receives bogus key presses such that I can't program it.  I've tried covering every LED I could find with electrical tape but that didn't help.  If I plug the flirc into my laptop then I can program it successfully but when I plug it back into the mythbox it keeps on getting random button presses.
>
>If the new mythbox was emitting IR randomly then that might explain both symptoms but I've done everything but wrapping the whole machine in a light proof bag.  I guess that'll be my next step but maybe these two problems are not related?
>Any suggestions and/or brilliant ideas?
>
>
>thanks for reading,
>Matt

The operation of IR receivers changed drastically after 10.04 - the
drivers for most moved into the kernel.  This tends to break LIRC
operation when you upgrade.  I found this page:

 http://linhes.org/projects/linhes/wiki/Architecture_and_Customization

to be a great help in working it all out with my MCE remote and my
Hauppauge Nova remotes.  The page tells you what tools to use for
debugging each stage of operation.