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KX-155 LEDs



 
 
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  #11  
Old November 18th 03, 09:00 PM
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John Purner wrote:
: I have the same problem with one of my KX155's and my ADF. Funny thing is
: that about five minutes after takeoff. The problem clears up. It seems like
: low voltage, but it isn't.

As I said it my post, I'm pretty sure that it's a pseudo-grounding
of the high-voltage that runs the displays. They're not LED's, and they
require a fairly high voltage, which is easier to bleed off due to
humidity. It's definately high enough to make you notice if you
accidentally brush up against it!

-Cory


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  #12  
Old November 18th 03, 10:34 PM
Victor J. Osborne, Jr.
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Related perhaps: My display is to dim to read at night. If I sine a
flashlight at the sensor (left side) the display brightens up. Any
suggestions?

--

Thx in Advance, {|;-)

Victor J. (Jim) Osborne, Jr.



take off my shoes to reply


  #15  
Old November 19th 03, 04:26 AM
Steven Barnes
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One of my co-owners flew the plane a couple days after the digits vanished
on me. He said it worked fine. Hmmm.
I was very cold on my flight. Enough that I could see my breath. I wonder if
that had something to do with it.

"John Purner" wrote in message
.. .
Aaron,

I hate to press to much but I really need the help. How exactly do you
remove the displays?

Thanks very, very much

--
John Purner
Editor - The $100 Hamburger
http://www.100dollarhamburger.com
"Aaron Coolidge" wrote in message
...
wrote:
: John Purner wrote:
: : I have the same problem with one of my KX155's and my ADF. Funny

thing
is
: : that about five minutes after takeoff. The problem clears up. It

seems
like
: : low voltage, but it isn't.

: As I said it my post, I'm pretty sure that it's a pseudo-grounding
: of the high-voltage that runs the displays. They're not LED's, and

they
: require a fairly high voltage, which is easier to bleed off due to
: humidity. It's definately high enough to make you notice if you
: accidentally brush up against it!

: -Cory

John, Cory, try this:
Take the displays out. Burnish the silver contacts on the displays.
I used a pencil eraser. Note that the contacts are not gold, if they
were they would not tarnish. Put a bead of dielectric grease on the
display's contacts. This will create a gas-tight contact, and keep
the condensation from bleeding off the +150V used to light the
displays. Put the displays back in.

This is what Conrad up at the Radio Shop at KORH did to my KX155's
when I was having similar difficulties a few years ago. No further
problems.

--
Aaron Coolidge (N9376J)







  #16  
Old November 19th 03, 06:24 AM
Aaron Coolidge
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John Purner wrote:
: Aaron,

: I hate to press to much but I really need the help. How exactly do you
: remove the displays?

: Thanks very, very much

John, this is for the King Crown equipment (KX155, KN62, etc).

Take radio out of plane. Remove front bezel, there are small philips
screws on the sides or top & botton of the radio. You don't need to remove
the knobs and switches (in fact, you can't until you've removed the bezel).

Now, you'll be looking at the display. It's the very fragile, very expensive
glass thingy. On the bottom, you'll see a row of 20 to 60 bent silver metal
fingers - these are the radio side of the contacts. The display contacts
are the dull silver squares that these bright metal fingers are touching.

To remove the display, carefully slide it away from the fingers. This is
hard to explain without graphics, but the display will slide a small distance
directly away from the fingers (toward the top, on a KX-155), and then
the bottom (again on a KX-155) will pivot slightly inward and the top
slightly outward. This pivoting will allow you to take the display out
of the radio, moving it up and away from the radio.

There is a little stub on the back of the display; this is how Dale fills
them with neon. The stub is exceptionally fragile! The rest of the display
is pretty solid, though.

Now, you'll see those 20-60 silver-plated fingers on the bottom edge of the
display. You can "burnish" them to remove the tarnish with a business card,
a pencil eraser, or whatever your favorite burnisher is. Be careful, the
silver isn't very thick! NEVER use abrasives of any sort (well, a pencil
eraser is technically an abrasive, but it's very fine). Try not to touch
these silver-plated contacts as your finger oils & acids will tarnish
them again. Do a final cleaning with alcohol.

Now is the time to put a bead of dielectric grease on top of those silver
square contacts. If you don't have dielectric grease, you may be able
to get it at Radio Shack, a good auto parts store, or a boating store.
Don't use "white lube", it's lithium based and conductive. Don't use
"heat sink grease", or anything but silicon-based dielectric grease!

To put the display back in, reverse the process. Drop it into the plastic
carrier with the bottom angled in and the top angled out. Push the top down
while guiding the bottom into contact with those shiny metal fingers. You
can push the left a little, then the right a little, back & forth. Soon, the
display will pop back into place. You'll have a big glop of dielectric
grease on your dining room table, and on the front of the display.
Make sure that the display contacts and the radio shiny fingers are properly
aligned, and not touching 2 contacts, etc.
Clean the display face with alcohol (rubbing, not bourbon). Takes off
the fingerprints, too!

Put the front bezel back on, and the radio back in the plane. Presto!
No more funky digits! (Probably.)

What if this doesn't work? Then, the display itself is probably no good.
The neon gradually leaks out, and the display gets dimmer and dimmer.
When it's cold, the display is dimmer yet. If this describes the problem
you're having, you need a new display, which will cost around $200.

Good luck! (PS, to email, remove 'spam' and 'off')
--
Aaron Coolidge (N9376J)
  #17  
Old November 19th 03, 06:27 AM
Aaron Coolidge
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Steven Barnes wrote:
: One of my co-owners flew the plane a couple days after the digits vanished
: on me. He said it worked fine. Hmmm.
: I was very cold on my flight. Enough that I could see my breath. I wonder if
: that had something to do with it.

I have seen a couple digits on one of my KX155's stop working in extreme
cold. I haven't been able to fix this, except by GENTLY pushing in on
the translucent lens, which makes them come back on. Usually by 1000' AGL
climbing out they're back on and stay OK for the rest of the day.
I suspect there are some questionable contacts that the extreme cold
makes, uh, more questionable.

--
Aaron Coolidge (N9376J)
  #18  
Old November 19th 03, 03:27 PM
[email protected]
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Aaron Coolidge wrote:

: John, Cory, try this:
: Take the displays out. Burnish the silver contacts on the displays.
: I used a pencil eraser. Note that the contacts are not gold, if they
: were they would not tarnish. Put a bead of dielectric grease on the
: display's contacts. This will create a gas-tight contact, and keep
: the condensation from bleeding off the +150V used to light the
: displays. Put the displays back in.

I'll give that a try. I wasn't really excited about taking it
apart too much, since it works fine 95% of the time. Of course the 5% of
the time it doesn't work is before it dries out on a nice, humid, damp IFR
day when having a 2nd nav shortly after takeoff would be nice...


-Cory



--
************************************************** ***********************
* The prime directive of Linux: *
* - learn what you don't know, *
* - teach what you do. *
* (Just my 20 USm$) *
************************************************** ***********************

  #19  
Old November 19th 03, 04:38 PM
Ron Natalie
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"Aaron Coolidge" wrote in message ...

Take the displays out. Burnish the silver contacts on the displays.
I used a pencil eraser. Note that the contacts are not gold, if they


They probably are not silver. Silver is too soft and tarnishes worse
than these do. They're probably some alloy of tin.


  #20  
Old November 19th 03, 11:25 PM
David Megginson
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Steven Barnes wrote:

One of my co-owners flew the plane a couple days after the digits vanished
on me. He said it worked fine. Hmmm.
I was very cold on my flight. Enough that I could see my breath. I wonder if
that had something to do with it.


Probably. I fly right down to -30 degC, and I notice that my KX-155
display gets extremely flakey on cold days until the plane starts to
warm up.


All the best,


David

 




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