JR radio internal battery

Hi

I bought an old JR X347 on eBay. The backup battery was about to fai and I replaced it without any backing voltage. Transmitter switched o without any problems (of course the model settings were lost, bu still, they weren't mine :) ), so maybe there are different versions o this transmitter, or maybe I was just lucky. That time :) But several days later my wife accidentally pulled the charging cor and JR hit the floor. Two days later transmitter died, switching it o brought only a light tick from the speaker. I guessed, that the CPU' crystal was broken. I soldered another xtal and JR turned on (but th channel times and timer were way off...). I had to order replacemen crystal (especially manufactured for me because of unusual frequency and after a month of waiting for new crystal my X347 was again up an running

-- MiQ2

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Which country are you in? That would make all of the difference in the world. So to speak.

Ed Cregger

Hi

I'm from Poland, but my JR is from Germany :) It's model number is probably more important - it's NET-C127EZ

Mik

-- MiQ2

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Just for a future need incase

The following was posted somewhere on the Internet

Before I start, I need to mention that most of what I talk about here shouldn't be attempted by everybody. If you have any doubts, send it in for service!

So, here's my story.... I've had my JR X-347 for 13 or 14 years now, and it's been one of those expensive purchases that I haven't once regretted. It was, and still is, an excellent radio.

My backup battery started to fail, giving me the "BACKUP ERR" message. Not to repeat too much of what's already been said, the battery is on the front side of the circuit board that's behind the buttons on the front side of the controller. I should warn you that if you take this apart, it is VERY difficult to get both the springs and buttons back in place! So don't even attempt this unless you're totally committed to doing it yourself.

I replaced the battery with one I ordered from

item number 614-CR2032FH-LF, and cost about $8 including shipping. (Mouser doesn't have the $25 minimum order that Digikey has) It's the same size battery, and has the tabs on it so you can solder it directly to the circuit board just as the original battery. I should also mention that if your soldering (and desoldering) skills aren't very good, you should reconsider even attempting this.

I found this out the hard way, but you'll want to solder or clip a 3V voltage source onto pins common to the battery before you start. Then replace the battery, remove the voltage source, put everything back together, and you're done.

If you weren't paying attention, or you just happened to have replaced the battery without knowing that you had to apply the 3V voltage source (as I found out the hard way), you'll turn on your radio and nothing will come on the display. You'll need to reset the radio's microcontroller. Thanks to André, I played around with the pins a little and found the right ones to do the trick. If you look at the picture attached to this message, you short out the red pins with the controller turned on. The controller will beep and go into a calibration mode. You probably don't want to mess around in there at all, but just turn off the radio and turn it back on, and it should be back to normal.

Now, I've been to other message boards and they suggest that it needs to be recalibrated after you replace the battery as I did. The mentioned recalibrating the battery voltage and the stick throw limits. The configuration menu you see when you first reset the microcontroller appears to set all of these. I plan to hook up my scope to the battery to recalibrate that, but that's about all I would know how to do. I haven't yet found any information on how to calibrate the rest. I did notice that some of the values are non-zero, so I'm hoping that it had some sort of non-volatile memory and saved the calibration settings, but I'm not sure if that's the case or not. If it is, everything is good. If not, then I'll probably have to send it in to get it calibrated anyway. I would also suspect that a recalibration might be necessary once the "BACKUP ERR" message is seen for the first time, regardless of whether or not you hooked up a voltage source when changing the battery out.

Ryan

P.S. If the picture doesn't show up, look under the plastic film on the circuit board the battery was on. You'll see an "R" on a wide trace. If you follow this trace back to the battery, you'll notice it's a ground trace. The microcontroller pins are to the right of the "R". If I was using my head a little more, I would have thought to try to reset the microcontroller, looked up the pinouts of the controller, and found the reset pin. They typically have a reset pin that you either pull high or ground out to reset the microcontroller. I don't know if the pin I found is the reset, and I haven't looked up the microcontroller. So there's a chance that it is something else that just happens to reset the microcontroller. Again, try all of this at your own risk! But anyway, it's the fourth pin of the microcontroller starting with the pin on the bottom left, if you're looking at the side of the circuit board with the traces.

P.P.S If you want to know about what the service menu does (for calibration, etc...) check out:

frenchomebuilder Wrote: > Look the board on wich is located the BU bat. Under the piece of > plastic, is written "R" on a large vertical track. Close on the right, > 2 pads to be shorted. The back part of the radio must be connected. > Switch on power , short the points just a time, and life is at new > going on . > Excuse my poor english. > André

Hugh

MiQ27 wrote:

I bought a new JR X-347 in 1992. Flew it a few times, fell ill and it has sat ever since. Yes, the backup battery died long ago.

I did change the main battery a couple of times, but never got back to it. Oh, I did use it with Real Flight Sim #1 for a while, so it isn't absolutely pristine, as far as stick pot wear is concerned, but still very low time. It looks brand new.

When I got back to flying again, I picked up an 8103 and eventually a 9303. Now both of them are sitting since I moved to Spektrum and Futaba 2.4 GHz stuff.

I guess it is time to sell off some of the old systems since I have no intention of going back to six meter or 72 MHz freqs.

Ed Cregger

Hi Ed, If you decide to sell your 9303 please keep me in mind. I have a 9303 with an XPS Extreme Link 2.4GHz module. Should need arise I can just plug in my

72MHz modules. Why? If I must send one the other back for maintenance I am not grounded. Having a spare 9303 would eliminate being grounded when a TX required maintenance. IMHO, the 9303 is the best (Futaba fans - I said IMHO ;-)) All early reports indicate that the FASST system is good also but the Spektrum low voltage drop out problem has caused many crashes including one by QQ. Good luck with your new systems and don't let that 9303 gather dust. It deserves a loving owner! :-) Ed, why not keep that magnificent 9303 and buy a spectrum module to replace the 72MHz module? *Or* go XPS - cheaper, more reliable, and more options.

I hear you, Ed. I'll keep you in mind.

I have thought about doing some of the things you mentioned, with the third party 2.4 GHz stuff.

Ed Cregger

Hi Ed, Check out XPS here;

You're in for a surprise. Jim Drew is the CEO, and he is a pilot. Jim spends a great deal of time on his NGs answering questions and listening to suggestions, many of which he has adopted by changing firmware *and* hardware! Check out the

*Forums* tab in the left frame and don't neglect to scroll all the way down on the main page for a complete description of the XPS system. By the end of July Jim anticipates selling 10K units. That ain't bad for a new product and no commercial advertising!

Thanks for the advice, Ed. I may end up doing as you have suggested. The voltage drop problem attributed to the Spektrum systems has been bothering me too, as I have read about it, not through personal experience.

Ed Cregger

To bump an older thread:

I replaced the lithium cell in my X347 last night and it's almost back up and running. The problem is that it's showing the main battery voltage as being 6.3V when it's actually 10.5V. This is way outside of the service menu's ability to tweak - anyone got any ideas?

I have an XF421. On the main PCB there are a pair of pads that when shorted will perform a reset. The set will beep then enter a state in which the volt display can be calibrated. Once the set is powered off it leaves this state.

If X347 behaves like XF421, then to take advantage of it: Hook up a calibrated volt meter to the battery. Perform a reset. Use the up/down keys to adjust the display to match that on the volt meter. Cycle power to the set.

THanks for the reply. I had tried that, but it seems like the maximum you can adjust the voltage by in the service menu is about +-1V, while the calibation is out by about 4V.

I too am an owner of an aging JR X388S radio that recently made the 'beep of death' with the unwanted text "BACKUP ERROR"! On closer investigation (i.e. springs and buttons going everywhere) I discovered that it was far easier to just purchase a replacement button cell lithium battery with out the fancy spot welded tabs. I just soldered two short leads to the +ve and -ve sides of the button cell and then soldered the free ends to the respective +ve and -ve points on the circuit board. However, I did discover that when I tried to turn the transmitter back on to see if I had removed the annoying 'beep', the transmitter did nothing...power on but no one home...no noises or any display?? Remembering an older post about the need to jumper across terminals...I did the very technical thing and turned the transmitter off and then licked the tip of my pointer finger and ran it over the circuit board behind the LCD display...turned the transmitter back on and the old girl had come back to life!! (this method was re-tested 15 minutes later as I needed to solder longer wires to the button cell so I could glue it to the inside of the back cover once I put some heat shrink around the new button cell battery)

I realise this is an older thread and my reply has come many years later, but maybe it may still help someone who is looking to revive an old JR radio like I was.