KNS-80 display has gone haywire...

Hello,

Our KNS-80 today wasn't 100%. Infact, for most of the day it was U/S.


Here is some background... today was cold...-15C (5F). I turned on the
heat in the hangar about 90 minutes before the flight so that the cabin
would get warm.

Once i started the plane and turned on the avionics master, i noticed
that the KNS-80 didn't work right. All the lights behind the numbers
were on and flickering... random garbage was just coming on the display
and changing about 5 times a second.

I left the unit on hoping that perhaps it would "heat up" and that was
the problem. After a long taxi the display finally stopped flickering
for about 10 minutes. I noticed during that time though that the NAV
flag would go in and out even though we were within 10 miles of the
VOR. Then all of a sudden, after about 5 minutes in the air, the
KNS-80 went back to flickering.

The unit seems seated properly -- it hasn't been removed at all.

Any thoughts?

-Dico

Dico wrote:
Hello,

Our KNS-80 today wasn't 100%. Infact, for most of the day it was U/S.


Any thoughts?

-Dico


Condensation?

I really hope thats al it is.

Taking it out today and we'll see.

-dr


Dave S wrote:
Dico wrote:
Hello,

Our KNS-80 today wasn't 100%. Infact, for most of the day it was U/S.


Any thoughts?

-Dico


Condensation?

On Tue, 23 Jan 2007 04:55:19 GMT, Dave S
wrote:



Dico wrote:
Hello,

Our KNS-80 today wasn't 100%. Infact, for most of the day it was U/S.


Any thoughts?

-Dico


Condensation?

That would be my thought as well. OTOH those things are getting old!
The one in the Deb works pretty good, most of the time. It does not
like to set in a cold hangar for a few weeks either.
Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

On Jan 22, 1:31 pm, "Dico" wrote:
Hello,

Our KNS-80 today wasn't 100%. Infact, for most of the day it was U/S.

Once i started the plane and turned on the avionics master, i noticed
that the KNS-80 didn't work right. All the lights behind the numbers
were on and flickering... random garbage was just coming on the display
and changing about 5 times a second.



Any thoughts?

-Dico

Hi,
My stack has a KNS-80 and the rest of the silver crown radios from
circa 1980. My KNS-80 stopped working a couple of years ago, so I had
it serviced at my local avionics shop (Freedom Avionics at BJC). In my
case, they had to replace the processor, and cost was about $300. In
addition to the KNS-80, the plane also has a KN-53 VOR receiver. Last
year I had trouble with intermittent display. I tried sliding the
radio from the rack and cleaning the connector and reseating, which
helped for one flight. I took it in to the shop, and it was a display
problem. Apparently this is pretty common with this vintage of Silver
Crown radios. It can be opened up, and the connector to the display
itself removed, cleaned and tightened. I think this is what the shop
did, as they only had labor on the repair invoice (no parts). It was
about $200.

Good luck and safe flying,
Brian

Dico wrote:
Hello,

Our KNS-80 today wasn't 100%. Infact, for most of the day it was U/S.


Here is some background... today was cold...-15C (5F). I turned on the
heat in the hangar about 90 minutes before the flight so that the cabin
would get warm.

Once i started the plane and turned on the avionics master, i noticed
that the KNS-80 didn't work right. All the lights behind the numbers
were on and flickering... random garbage was just coming on the display
and changing about 5 times a second.

I left the unit on hoping that perhaps it would "heat up" and that was
the problem. After a long taxi the display finally stopped flickering
for about 10 minutes. I noticed during that time though that the NAV
flag would go in and out even though we were within 10 miles of the
VOR. Then all of a sudden, after about 5 minutes in the air, the
KNS-80 went back to flickering.

The unit seems seated properly -- it hasn't been removed at all.

Any thoughts?

-Dico


There are integrated circuits inside the unit seated in sockets.
In my KNS-80 similar symptoms were due to bad contact in sockets,
so just re-socketing all the socketed IC's helped, and it has worked
several years since.

--

Tauno Voipio (PA28RT-201T, OH-PYM)
tauno voipio (at) iki fi

Another poster mentioned socketed chips being a problem. Try re-
seating them, and also the connectors between circuit boards. King
came up with numerous modifications to deal with problems encountered
in the field, and I believe "Mod 10" dealt with contact problems. Your
KNS-80 should have a modification record plate on the rear - check to
see which ones have been done. Perhaps someone alse out there can
furnish a list.

If your efforts are not successful, consider picking up a replacement
KNS-80 on eBay - it may be cheaper than repairing yours. Quite a few
serviceable radios are turning up as people upgrade to whiz-bang color
screen boxes. Look for a yellow tagged unit and Mods through at least
10.

David Johnson