sticky switches on old transponder

Discussion in 'Instruments / Avionics / Electrical System' started by dick ripper, May 14, 2010.

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  1. May 14, 2010 #1

    dick ripper

    dick ripper

    dick ripper

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    The push button switches on my old ARC (Aircraft Radio & Control), a division of Cessna, RT-859A p/n 42260 102P are sticking and sometimes inoperative. The transponder has 6 square pushbuttons arranged ID-ALT-TEST on top row with ON-STBY-OFF
    on bottom. (BTW, code switches are rotating lever type and working well).

    It has been so long since used that possibly the switches need some cleaning attention <G>. 1st question is what cleaner to use on contact surfaces?

    Looking into the switch mechanism itself (beyond the pushbuttons); it appears that ON and OFF toggle back and forth while STBY should push inwards and hold with another push releasing the standby thereby resulting in ON, STBY & OFF in "neutral". Not sure in that logically STBY would leave ower on...

    Sorry for poor description but don't have a manual to state how switches are to work. ie: push,toggle,interlocks,etc...
    Question2 is how does any other pushbutton transponder's swtiches work ?

    Thanks, Dick
     
  2. May 14, 2010 #2

    lr27

    lr27

    lr27

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    I've saved some contacts in electronics by using ACF 50 (or an equivalent product, Corrosion Block). Probably you want to clean up the surfaces first. If you can get at them, a pencil eraser will do. I have a calculator which had green, corroded battery contacts 15 years or so ago. I cleaned them up and put this glop on them, ONCE, and they've been good ever since.
     
  3. May 14, 2010 #3

    Tom Nalevanko

    Tom Nalevanko

    Tom Nalevanko

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    Buy a can of Contact Cleaner and spray everything aggressively; exercise all the buttons and then let it sit for a day. Then power it up.

    I use this approach on a lot of electronics and it often works. First, however I power down and up and down. Good luck.
     
  4. May 16, 2010 #4

    dick ripper

    dick ripper

    dick ripper

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    Thanks. Results of liberal contact cleaner were negative. Did open up case and switches enough to verify IDent & Test are momentary pushbuttons while ALTimeter latches and unlatches. ON & OFF are to physically toggle per visual exam of them. StandBY has no wires (but appears visually to maybe turn off both the ON and OFF push aspects..)and I don't know what it's function is supposed to be. Anyone care to tell me??

    Dick
     

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