I had my DX7s open while trying to connect to an EzUHF - see post on FPVlabs about that here

While I had it open, I thought I would solve an irritating issue with the DX7s. The designers apparently decided to save about $0.05 per unit by not including a backlight LED! Duh! (any excuse to market an 'upgrade' )

I used two white SMD LEDs, two 100 Ohm SMD resistors, a small switch and some wire (oh - and a bit of white card). Note you can also use normal components (with legs). They are easier to solder, but perhaps harder to fit in.

1. Take it all apart (see elsewhere, like the manual, to see how)
2. Cut the white card to fit behind the LCD screen
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3. Bend the card a bit to make the light, which will come from the bottom, catch the card evenly
4. Use some non-corrosive glue, like contact, to glue the bottom of the card to the PCB board, checking the LCD will still fit. The top of the card should touch the lcd screen, the bottom should clear it by as much as possible.
5. Drill small holes to make space for the toggle switch to protrude through the front panel.
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Make sure the switch will not touch any other component when all is assembled
6. Smooth this out into a rectangle to allow the switch to move when in place
7. Glue the switch carefully in place (I used cyano and kicker)
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8. Solder the SMD resistors to each LED. Then add wires to reach the vibrator motor positive on the one side, and the switch on the other.
9. Use a 1S battery to check polarity, to make sure things are the right way around
10. Connect the positive side of the LED/resistor pairs to the + of the motor connector
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11. Connect the negative to the switch, and the other switch terminal to negative (ground) which you can find anywhere closeby
12. Before assembling, use some tape to keep the LEDs facing upwards into the gap between the card and the LCD screen
13. Switch the LED's on when needed, and keep them off otherwise for max battery life
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Hope that's useful to someone!