PCM 10X transmitter
US versions have a fuse in place of the diode, but the fuse looks much like a diode. US versions use the fuse to protect the battery from an overcurrent situation, but still allows the battery to be cycled. If any problem occurs without the fuse or the diode, the battery will be damaged, and if the problem is severe with the pack in the transmitter it may also damage the TX as well.