sticky switches on old transponder

HomeBuiltAirplanes.com

Help Support HomeBuiltAirplanes.com:

dick ripper

Member
Joined
Jun 18, 2009
Messages
23
Location
Lakeland, Florida, USA
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
 

lr27

Well-Known Member
Joined
Nov 3, 2007
Messages
3,822
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.
 

Tom Nalevanko

Well-Known Member
Joined
Oct 10, 2007
Messages
1,324
Location
Alpine, WY
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.
 

dick ripper

Member
Joined
Jun 18, 2009
Messages
23
Location
Lakeland, Florida, USA
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
 
Top