Sunday, 11 May 2014

Making my Lenovo MCE RC-6 IR Receiver immune to interference by my TV backlight

Sadly due the newer technologies employed in CFL bulbs (which incidentally is the technology behind my TV) emit a lot of IR interference on the frequency ranges used by the older IR controls. Vishay publishes a summary which goes into more technical detail here: http://www.vishay.com/docs/80072/disturan.pdf.

My MCE receiver is an RC-6 system by SMK RXX6000-40 branded Lenovo, if you want to buy one of your own then please checkout eBay.


HP Remote with USB Receiver RC-6 [Taken from eBay auction linked here]

However despite being aesthetically excellent the receiver suffers from interference from the TV backlight which makes it unusable if the room light isn't bright, wholly unsuitable for certain movies.

This is a pretty common problem for the older IR systems however newer IR receiver modules have been enhanced with better filtering systems.

 Opening the receiver is easy, a single screw hidden in the center of the label and the top and bottom come apart to reveal a single PCB.


The IR module is the black module standing up on the lefthand edge of the PCB (the "front" of the PCB is the south west side). Careful scrutiny of the top of the module reveals it is a Vishay Siliconix TSOP34838, a 38kHz filtered IR module.
Consulting the datasheet from Vishay, http://www.vishay.com/docs/82489/tsop322.pdf, we can see that there is another, pin compatible module, with an enhanced filtering system (Vishay's Active Gain Control 4 or AGC4) to exclude the interference the TSOP34438 is vulnerable to.

I have the new module on order and when it arrives I'll post the results.