Trouble removing King KX-155 from recent panel

Discussion in 'Technical Corner' started by JimNtexas, Oct 17, 2019.

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  1. JimNtexas

    JimNtexas Pattern Altitude

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    I had something strange happen today. A couple of weeks ago our club's C177RG suffered failure of the PS Engineering audio panel. PS Engineering was great, they gave me an RMA, I sent it to them and got it back in about a week, looking brand new. Cost ~$600 plus shipping to them.

    So today I go to put the refur audio panel back in the Cessna using a 3/32" driver, it worked fine, but when I selected the #2 KX-155 radio the audio panel did not key when the PTT was pressed. No sidetone, no 'tx' indication on the KX-155 display, and no radio output. :(

    Is there a problem with the new audio panel, or the #2 King radio?

    Well, our club has a Warrior that also has a KX-155. No problem I thought, I'll pull the Warrior's KX-155, plug in the Cessna's KX-155, and see if the Cessna radio works in this other airplane.

    Now comes my problem. This is a ~2 year panel in our Warrior, the KX-155 sits right below a GNS-650.

    So I put my 3/32" in driver into the tiny hole, and start to turn. In all other times I've done the radio begins to back out as soon as you start turning. Not today. I can turn this KX-155 release mechanism lock to lock and the radio does not move at all. I tried a bunch of times, the radio never move even a fraction of an inch.

    Is it possible that new panels use some other method of securing radios in light planes instrument panels, besides the 3/32" drive procedure?

    Or do I need to dig it out with a crowbar?

    I'm befuddled, and suggestions as to how to get this radio out would be appreciated.
     
  2. kgruber

    kgruber En-Route

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    Take the radio that is above the KX-155 out and examine the mechanism.
     
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  3. EppyGA

    EppyGA Touchdown! Greaser!

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    How many turns did you go? If the slot is wider it might take several turns before the mechanism contacts the back of the slot and starts to move the radio.
     
  4. JimNtexas

    JimNtexas Pattern Altitude

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    It takes a lot of turns to take these radios out, I've done it before. It sure feels like the jack screw is turning all the way from tight to lose to tight. Probably taking the box above the radio is a good idea. But that's a fairly new GTN-650 that we paid a boat load of money for, and I'm kind of reluctance to mess with it.

    I may try to borrow somebody else's KX-155, since I can't get ours out of the panel for the moment.
     
  5. SoCal 182 Driver

    SoCal 182 Driver Pre-Flight

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    :yeahthat:
     
  6. bbchien

    bbchien Touchdown! Greaser!

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    The lock lug does not rotate until it reaches the end of travel of the screw, and it’s a long one....
     
  7. JimNtexas

    JimNtexas Pattern Altitude

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    I’ve done this before, when you start turning the tool the radio starts moving immediately. You are correct, it takes a lot of turns, but the radio does move as you turn.

    I think the suggestions that there may be something amiss with the screw mechanism is credible.

    Sine this is a fairly new panel I was afraid there might be some new to me system for holding in the boxes. I think that fear is unfounded.
     
  8. wilkersk

    wilkersk Cleared for Takeoff

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    When you get it out, and before you put it back in, turn the hex head all the way counter clockwise till the dog-ear thats closest to the face of the radio is pointing down. With the hex wrench in one hand, holding the dog ear in this position, push the radio in gently till this down dog ear contact the open notch in the end of the tray.

    Now, turn the hex wrench clockwise while pushing gently. The down dog ear will move 90 degrees and the dog-ear behind it will rotate down into the enclosed slot and grab the tray bottom and draw the radio into the back plate, seating the connector. Turn the hex wrench only enough to firmly seat the connector and so the face plate of the radio is even with the stack. Don't over tighten it!

    The next time you remove that radio, just turn it enough that the latching dog ear travels along the hex screw and pushes against the slot, driving the radio out from the tray enough that the other dog ear drops into the open notch at the bottom edge of the tray. Do not turn the hex key any more. The radio should pull easily the rest of the way out of the tray.

    Reading this might not make sense at first. But, if you study the mechanism, the light bulb will go on and it will make perfect sense.

    Every King radio I've ever pulled out of a tray (other than brand new) has had a warped tray and worn latching mechanism because people really don't understand how this fairly simple latching mechanism works.