VP-101 Pager LED Power Light Modification

December 2011

Click a picture to Supersize it.
1.

Project Details:

My church was going to replace our pager set because the batteries die during the week. Strange..

So I asked if I could borrow a pager to run an experiment. I measured the "on" current and then the "Off" current to verify no leakage while in the "Off" position. Sure enough, the power switch seemed to be doing it's job perfectly.

So if the switch works then that leaves only one way the batteries could get drained...User Error!

I asked How? My answer was: I think the power switch is not getting fully turned off. The  switch has three positions so maybe the user slides it and thinks it's off but it's still on. The original units DON'T have a power led so it's hard to tell when the unit is on.

Solution:

Add a tiny power led! Don't turn it on too bright so we don't impact the life of the battery.

The unit shown in this picture has been modified and a power LED has been added. It looks like it's original too! Lets look at how to add one.

Feel free to contact me if you want to talk about modifying your pagers to add the LED.

 
2.

Just another view
3.

Turn the pager on it's side to begin the operation.
4.

Remove the battery cover and two screws.
5.

Carefully pry off the back cover using a small tipped screwdriver.
6.

The guts exposed!
7.

Pop out the board and then keep it held up so we can drill it.

8.

Choose a drill that is slightly smaller than the LED your going to use.
9.

Place the LED in a holder so we can work on it. The Longer lead is typically the Anode (+) but that's no always the case. You can use your Ohm meter to check.
10.

I used a 4.7K resistor to set the LED current.

3V -1.2V LED =1.8V

1.8V /4.7K = 380 uA

I think my actual current came out higher. Bench test this to make sure you are happy with your LED brightnes.
11.

Trim the LED leads. Keep the Anode slightly longer
12.

Bend the Anode lead up to make a ring. Do the same for the resistor but before you close the ring, insert it into the LED Anode ring.

Clamp tight with pliers.

Solder the joint.
13.

Tack on two different colored 2 inch wire wrap wires as shown. I assigned Green = ground.
14.

Here is our completed LED assembly. Test on the bench using the two batteries for the pager.
15.

Insert the LED assembly into the drilled hole. Use the screw driver to force it in a little. It should be snug if you chose the correct drill.
16.

Add some hot glue to insulate the solder joints and hold the LED assembly in place.
17.

Route the wires so they come out as shown and then reinstall the board.
18.

Press the green wire against the long soldered ground pad using your soldering iron. The insulation will melt and the wire will be bonded. Tug on the remaining wire to make sure it firmly attached.
19.

Trim the excess wire.
20.

Solder the Blue wire as shown. Make sure the wire will clear the protective switch gasket thingy.
21.

Trim the excess wire.
22.

Put the batteries in the pager and test it out!
23.

Reassemble the unit and give it one last test.

That's all!

I had about 15 pagers to mod so I set up an assembly line to do it.

I estimate I can mode one in about 10 minutes.

The first one will always take longer of course.

Finding the parts will take even longer!

But in the end the frustration level should be reduced when the batteries don't have to get replaced every week.

 Contact me to let me know if this procedure works for  you.

Thanks for looking!

Mark