Spmar410 - on board capacitor
 

I have a couple of the new AR410 receivers; these receivers have a fairly large ( in size ) cap that is soldered to the board and then held in position with a hot glue of some sorts.

One of my units had a cap that began to swell ( never had more than 2s lipo on receiver ) so I removed the cap from the board. To my surprise I found the board would still power up and all channels will work.

What is the purpose of this cap?

Probably there to smooth out voltage ripples and voltage spikes.

Sort of my thought as well but was not sure. Certainly the receiver still works and now with the cap removed it fits even better in small spots. With the case these are really too big to use in a DLG so no idea why Spektrum is pushing it as so. With the case off the fit is much better and with the cap gone it is even better. :)

If I may, rather go to an electronic shop and purchase a replacement capacitor of the same size and voltage (for example - 4700 uF,16V - it is printed on the side of your capacitor). This capacitor provide extra power when you make a severe deflection with your servos, like full rudder at high speed. Without this capacitor, your voltage powering your receiver electronics might drop significantly for a very short time and your receiver might go in a start-up sequence. The result is that you will be without a functioning receiver for a second or two while your aircraft is in the air.

Think of it this way - why would the manufacturer insert an unnecessary capacitor in every receiver? They could save money and sell the receivers at a better price than the competitors.

Just watch out, your capacitor has a negative and positive side, it matters which leg you solder into which hole. If you have never done this before, rather take it to someone who is familiar with working on surface-mounted electronics. It is a simple procedure but too much heat via the soldering iron could damage your receiver board.