Sennheiser EW100 G2 Repair

We use these Lavalier microphone transmitters with the PA in my local church. They are generally well constructed, and I have not had to open one until recently. The plug-in microphones do suffer, however, and I have to re-wire the microphone itself or connector about once a year. New ones don't fare much better than my repaired ones, so I seem to be doing a reasonable job.

 

Sennheiser EW100 G2

This transmitter failed completely, which is a first despite years of use. Disassembly revealed a very compact design, and an obvious issue. A power inductor had broken, so I suspect the transmitter had been dropped onto a hard surface. Finding a replacement was tricky, as I had to match not only the electrical characteristics, but also the replacement had to fit in the limited space available. After examining the wreckage and the datasheet for the associated boost regulator IC, I selected an EPCOS B82472P6223M000 (22 uH +/-20% 1.45A) part as a good match. Replacement was straightforward.

Inductor Replaced (top centre of PCB)

The inductor is the black square component at the top centre of the PCB. The associated regulator IC is on the underside.

The Inductor Shouldn't Look Like This!

After replacement and reassembly, everything worked as it should. The output signal is clearly visible using a FUNcube Pro+ receiver, which I find very handy for testing radio-related things.

Transmitted Signal

The main purpose of this post is to make life easier for anyone trying to repair one of these or a similar unit. I did see an advertisement offering replacement inductors at vastly inflated prices. I declined the offer, but it does imply that this is a known issue with these units.