I'd had my Taranis X9D+ transmitter for 5 years. It was right after applying an OpenTX update to the X9D+ that I was met with a new message after turning on the radio. I was informed that the real time clock (RTC) battery needed replacing. The RTC battery keeps the date/time working when you power off the X9D+. Lots of equipment have them and require periodic replacement. It is easy to do.
First, purchase a new 3 volt lithium CR1220 battery. They are readily available online and cost a dollar or two. Shopping around will get find you a vendor with free shipping.
After you have your new RTC battery, remove the main battery cover (bottom of rear case), unplug the battery, and set the battery aside. DO NOT work on the transmitter with the main power battery connected. It is a perfect recipe for shorting something out and smoking your transmitter.
There are six screws to remove so that the rear panel of the transmitter can be removed. A small Phillips screwdriver will do the job.
Sometimes one of the switches will separate from the case half it is mounted in (a couple of them are mounted on the seam of the case). To make it easy to ensure the switch is returned to its mounting location correctly, I always position all of my switches in the same direction. That way, I don' put a switch back in backwards, only to find out later when I do a pre-check on my plane and find out the flaps are going the wrong direction or something similar.
The front and rear case halves are easily separated once the screws are
removed. There are circuit boards mounted in both halves of the case with
ribbon cables connecting them together. Be gentle as you separate the
front from the rear. Leave the cables attached as there is no reason to
remove them. The RTC battery is mounted on the circuit board in a holder.
I've read that some transmitters had the battery on the opposite side of the
board but I've not seen that myself. The RTC battery holder is circled in
GREEN in the above photo.
NOTE: You can see that one of the switches, in the lower right corner of the photo, has slipped out of its mounting location. I told you it can happen.
The CR1220 battery is held in the battery holder with a little spring tension. I used the tip of a small screwdriver to pop it out of the holder. The positive (+) side of the battery faces up, in case you didn't take notice prior to removing it. Remove the battery and gently press the fresh battery into the holder.
Carefully join the two case halves back together, taking care to ensure no cables have been pulled apart and that no wires are pinched. Make sure any switches that dropped out of position are placed back where they belong. Be sure they are oriented correctly.
After replacing the six screws, plug the main battery back in and replace the battery cover. Power up your radio and navigate to the Radio Setup page (long press on MENU button) to set the date and time. You are done!
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