DarZeelon

I encountered a problem with my JR XP783 transmitter.


I last used it three weeks ago, flying my H9 Ultra Stick Lite.

It was totally uneventful. The radio performed perfectly.

This morning I wanted to charge the system and connected the transmitter to my charger.
The charger's voltage indicator displayed 0.00 V, no change. I have been using this charger for over 18 months and it has been performing perfectly and the polarity is correct. I connected it to another R/C transmitter and verified it indicates proper voltage.

Next I tried to connect the OEM wall charger to it. The LED did not go on.

I tried to switch the transmitter on, but the screen stayed off.

I thought the battery pack may be totally depleted; this would explain the zero voltage and no display (but it is unlikely to happen after only 3 weeks of idle activity).
But measuring voltage on the pack itself, showed over 9 Volts, I momentarily connected a DC motor and it ran fast. The transmitter should 'beep' as it declines to 8.9 V and below, but no beep, no display, nothing.

It cannot be the memory back-up battery, despite the 5 year age of this system, since I received no indication thereof and besides, it should not prevent charging the transmitter.


It seem like something as simple as voltage not reaching, or not being passed by the on-off switch, so voltage is neither displayed in the screen and does not power the system in the 'on' position, nor is it relayed to the charge socket in the 'off' position.

Has anyone here encounter a similar problem with his JR transmitter?

MO_Radio_Tech

You have a blown fuse. You can see it and test it by removing the moule and looking down into the radio. To properly replace it, you must remove the battery, 6 case screws and seperate the halves of the radio. Disconnect the two wire bundles. Then remove the screws that hold the back circuit board to the case. Then you can get at the fuse. Be sure to replace with the 3A fast-blow type. Make sure fuse is in tight. If not bend fuse clips before putting fuse in to make it snug.
Check solder joints at the charge jack. These may need repair as they often crack with age.

If the fuse is not the problem, you will need to send to a JR repair shop in your part of the world for repair.

The charge plug on the wall chargers often wears out, allowing a short and causing blown fuses.

Good luck.

DarZeelon

Thank you, Bill.


I just checked this and the fuse is, indeed, blown.

Coming to think of it, why is the fuse rated at 3 Amperes, when the transmitter uses only 250 mA during operating?
Even when charging I never ever exceeded 1.5 A and usually use only 1.0 A.

Are both working current and charging current, relayed through this fuse?

Mac_Man_UK

That is correct, the charge current does pass via the fuse.

[8D]

MO_Radio_Tech

Yes both charging and power route through this fuse.

DarZeelon

Bill, Mac,

So would you think a momentary current surge from the charger could have burnt it?

MO_Radio_Tech

yes