x10 IR 7243 reciever poor performance and fix

[m4rky_m4rk]

Hi,

I have had frustrating reliability issues with my x10 IR7243 receiver for a while now. At first I thought it was mains noise from my LCD TV and I bought a FM10 filter. That helped a lot but I still had some problems.

The receiver has an LED on the top surface which should flash when it transmits an x10 command. The problem is that when used as an IR receiver, as opposed to a wall mounted controller, the top mounted LED of the IR7243 was not visible from my seating position and so I was never sure if the x10 command was transceived and then issued or not. This lack of info lead to some incorrect assumptions about the reliability problem.

I therefore decided to take transceiver apart and added a front facing 4mm red LED. If you plan on doing this then its important to ensure that the forward voltage of the LED's are matched; otherwise only the lowest Vf LED will light! In other words you may need to replace the original LED as well as adding a second to ensure the Vf's are the same.

With this additional LED I was then able to discover that my reliablity issues were in fact a sensitivity to the light emiited by my LCD TV. Even indirect light was swamping the receiver. Having discovered this I then built a shade for the 7243 and now it works reliably. I was even able to remove the FM noise filter from the TV without any ill effect.

Hope it helps someone. The LED mod was cheap and easy if your OK with a soldering iron and a Dremmel.

[m4rky_m4rk]

Originally Posted by goooku

could you tell us a bit more about that shade ?
I know my LCD screen makes my settop box act weird...

Thanks

I can but it might not help you. It was nothing clever, just a Blue Peter job.

The IR receiver that had the issue is not very big, about the size of of two fag packets. Instead of having it up front like normal I put down one side of my kit so that it didn't have direct line of sight to the TV screen. I found that even indirect light bouncing of a nearby wall was enough to kill the sensitivity. I built a shade' like a camera lens hood out of black card. I more or less enclosed the enclosed the receiver so that it was shielded and only able to receive light directly from my seating position ie from my remote only. It worked brilliantly.

It does make me wonder if other IR receivers would improve their range if stray light was eliminated. I was surpised how sensitive it was to the LCD TV light. Even a black screen caused a problem. Perhaps its not black to IR though.