Hi,
I have my bedroom TV (upstairs) connected to my DirecTV receiver downstairs through a Gefen HDMI extender balun. This balun also sends IR signals from the bedroom to the Directv receiver. I use two Universal MX-500 to control the two TV in my house; the one in the TV Room (downstairs) and the one in the bedroom upstairs. This setup is one month old and it had been working fine i.e. I was able to properly control the DTV receiver in the TV Room from my bedroom's MX-500.

A couple of days ago the bedroom MX-500 stopped working. It controlled the bedroom TV OK, but not the DirecTV receiver downstairs through the balun.

These are the tests I made to diagnose the problem (with fresh batteries in all remotes):
The bedroom MX-500 works fine when taken downstairs to control the DTV receiver with line of sight.
The TV room's MX-500 does control the DTV receiver through the balun when taken to my bedroom. (same behavior as the other MX-500).
The original DTV remote CAN control the DTV receiver from the bedroom through the balun IR repeater. (the balun is working)

This indicates the following:
The bedroom MX-500 is working fine (since it works downstairs).
The balun IR repeater is working is fine since it can repeat the original DirecTV remote IR signals.

The only explanation I can think of is that the MX-500 lost IR power because it was working properly before, but the fact that the other MX-500 does not work upstairs does not support this hypothesis.

Can you please help me... I'm going nuts here.

Thanks