Written by Rob Bingham Thursday, 03 December 2009 01:03
At long last I have done my back light modification to my DX7 and have written a “How To” for anyone wishing to do their own. A list of components and their suppliers will be at the bottom of this page. Some of the Photo’s are not in focus, but it was too late once I loaded them to my computer as the Tx was back together. I also took this opportunity to do the ball race mod as well.
Now the boring bit:-
This is how I did mine, and it is entirely your responsibility and at your own risk if you copy this process. It will make your warranty void on your transmitter. It can also invalidate your insurance as you have modified the transmitter beyond it's original specification. Please take these warnings seriously and only carry out the modification if you are happy with the issues this could potentially raise. HeliTuning accepts no responsibility for any consequence of attempting this modification and it is done entirely at your own risk.
I carried this out following lots of research and contact with people in the USA and Canada for advice and components that they had used successfully.
1. Remove battery and back of Tx.
2. Remove internal screws on the bottom PCB marked on the photo below.
3. Slide grey tab down with finger nails to release the ribbon cable (do not pull cable before releasing clamp).
4. Lift PCB, swivelling the board from the bottom upwards. This will expose the LCD display that will just lift out.
5. Make a note of position of the plastic LCD retainers and then remove from LCD by sliding off sideways. There are 2 tabs that need to be trimmed flat, as shown in the picture shown below.
6. Using a thin blade (exacto/scalpel) carefully lift the corner of the silver foil backing on the LCD. NB, you must leave the “green” polarising layer in place. GENTLY peel off the foil and do not apply too much pressure on the glass screen or it WILL crack. Once foil is removed, there is a layer of adhesive on the glass that can be “rolled” off using your thumbs/fingers.
7. Cut your EL panel to size using sharp scissors only. Do not use a knife, the pressure can separate the layers of the panel.
8. Now solder on a length of twisted wire ( reduced RF noise) and use heat shrink to cover any bare wire. Use some black PVC tape to hold the panel to the screen, but not up to the ends where the plastic retainers fit. You need to keep the extra thickness of the panel to a minimum.
9. Re-fit the retainers to the screen. Do not use any pressure (you will crack the glass), then use the small location pins on the retainers to line up with the holes in the PCB. Now install the 2 inner screws but not tight. The screen is not going anywhere. Put the PBC back into the Tx and install the outer 2 screws. Gently insert ribbon cable back into its socket and press grey clip back into place to secure the cable.
10. Now for wiring it all up! I wanted to turn mine on and off, as and when I needed it, so I installed a toggle switch for this. Follow the diagrams for the wiring and make sure you use heat shrink on all the joints and use twisted cables.
11. I also opted to install the DE-SW033 at the same time, as this uses a lot less battery power. I use the V.in and ground from this to power my back light. See the photo below.
12. Make sure now wires are fouling the locating pins for the back panel. The inverter will need to be loose in the bottom left corner and it will just fit with the wires adjacent to the charge socket. The 5v voltage regulator will fit in the bottom right hand corner adjacent to the trainer socket. Please see photo below.
Now you should have this!
List of Parts I used
Red & Black Wire: Equipment Wire (7/0.2)
Ultra Miniature Toggle Switch
Voltage Regulator DE SW033: 3.3V switching voltage regulator
Voltage Regulator DE SW050: Switching voltage regulators
Servo ext lead. (I used both ends to make a plug and socket to disconnect the switch for easy removal of the Tx backpanel.
Heatshrink tubing. I used 3mm diameter.
Tools I used
Small Phillips Screwdriver
Exacto Knife and sharp scissors
Soldering Iron and Solder
Wire cutters and Plyers
Electrical PVC tape
Drill and 5mm bit (if fitting switch)
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