Tuesday, May 26, 2015

FT-707 repair (5) LED lamp replacement

Another fix on one of the FT-707 duo. This unit didn't have the VFO dial ligh's working.

I could had bought those small grain of wheat original bulbs for replacement, instead decided to try LED light on the display, thinking in long term without further maintenance. Got two 3mm high brightness white LED's and placed a 680 Ohm resistor in series across both to limit the brilliance, before placement tested with 330 Ohm limiting resistor and tough it was to much bright.

Here's the outcome (original unit on top, LED fitted unit bellow):

I guess the blue color is because the LED's are white and the rubber grommets blue, maybe with Yellow would stay close to original, anyhow I like it.

And night time, again LED unit bellow:

Now the fixing job, bellow picture, the board with the bulb and LED connections, I removed the frequency counter module (above the VFO box) to better access this board:

The rubber receptacles for the lamps with original bulbs still in place:

Removing them it's just a matter of gently pulling the blue cable. Inserting the LED's it's also easy.

It was a fast job, just need to pay a little attention to not break any of the cables that connect on the board. Fitting the square LED's on the openings of the from panel was also easy.


Don't know if you noticed and I just noticed yesterday, one of the units doesn't have the decimal points on the frequency display, I hope it's just a wire...or soon I will have a degree on FT-707 fixing!

Have a nice day!

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