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Very unusual. Light causes circut to connect??????!!!!

Hi, I bought an ipod with a broken menu button. Well i thoght I'd just have to resolder or buy a new switch.. I resoldered the switch with no luck and then I checked it with an ohm meter and it checked good. Now here is the Weird part, I was inspecting the board under my desk lamp with it powered on and the switch started working, well sort of.

If you shine light on part of the board it closes the circut like you pushed the button down!!!??? There is not an optical sensor that i can see anywhere near there, and it is away from the switch that doesn't work. It has some smt resistors in the area and some holes that appear to go all the way through to a chip on the other side.

So my question is what the heck is going on??? I've never seen anything like this before. It is not supposed to be light activated..

I'll put some picures up on my web server when I find my digital camera charger.

- Mike

Reply to
Michael Kennedy
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Some of the newer products are using IR interuption for the switching. They use an IR emitter, and receiver on the circuit board.

This is all surface mount technology. You will have to have access to the proper parts, service information, and the proper tools to do this type of service work.

Maybe the local rep for the manufacture can have it serviced for you at a reasonable price. Or, the person who you bought it from, found that it was not feasible to have it serviced.

Jerry G. ======

Reply to
Jerry G.

Well I had thought about "rigging" it by wiring a switch and a lightbulb in... A small flashlight bulb works just fine.(a mini-mag light bulb) The swithc appears to be a standard smt momantary push switch. The only thing IR on the board that I see is the sensor for the wheel. I can cover that up and it on the other side of the board. It doesn't do anything when you shine light on it.

The unusual thing is I have another Ipod and it doesn't do anything when you shine light on the mainboard. It is the same model and all..

Reply to
Michael Kennedy

You were right about the IR. I used a remote control to do the same thing as the light. So if I cant work anything else out I'll mount a IR diode inside wired in to the swithch. I don't understand why this works though. I don't see ant type of IR devices on the board.

Reply to
Michael Kennedy

This is because you are not able to recognize the IR components visually. Obviously they are there, or it would not respond to the light!!!

--

JANA _____

Reply to
JANA

Well the unusual thing is the fact it doesn't work on my working ipod. It is very likely there is some sort of ir device there. I just cant figure out why it would have infra red devices on the board to start with. It uses standard switches not infra red for the push buttons.

Anyway I don't know what or why its messed up but I'm taking the original switch and wiring it to an IR diode over the spot where it causes it to work.

Reply to
Michael Kennedy

How close are you getting with the light? Could you be causing some sort of thermal effect?

Reply to
Anonymous

That's what I thought to start with to start with also. But I found that it could be activated with an IR diode. I have isolated the spot. It is a testpoint that leads to a chip on the other side. The testpoint is a small hole.

I don't know what or why it works, but I wired an IR diode in and volia. The button is functioning how it should, except you can't do a master reset with it.

My theory on why it is working is that there is a crack in the chip on the other side. But since I know nothing about how chips work I don't know if that is a possible cause.

- Mike

Reply to
Michael Kennedy

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