What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

KING KLN-90B TROUBLESHOOTING IDEAS..

RV-4

Well Known Member
Hello Gents

I have a vintage King KLN-90B installed in my RV-4 and I have a bit of a snag with it and was wondering if someone here familiar with these old GPS would have a clue on what could be the problem..

it looks like that it is no longer seeing the satellites or at least it doesn?t after 1/2 hrs and I?m getting a ??FLAG?? annunciation when in the NAV window.

I tried a different antenna, made sure the coax was good, enter a present position just to give it a head start in finding where it is etc...but it still doesn?t appear to see the satellites...

In the ??STA+1?? window where you see the satellites it is looking at all I get are ??00?? for SNR & ELV ... After 1/2 hr today I had 1 or 2 satellites that were showing some sort of SNR ( Sound to Noise ) and elevation but that was it...

Any idea what might be the problem??

I?m thinking that the internal memory battery is either dead or very weak and the GPS has to find where it is every time it boot up and it takes a long time.. Am I right on this...??

If so, how hard is it to replace the battery if someone has ever done it??

Thank you for any info you may provide.

Bruno
[email protected]
 
The battery is not that hard to replace, but it is soldered onto one of the boards and takes some work to get at it.

Not sure this is your issue. You can tell the 90 what day and time it is now. That is what the unit needs to find the satellites. If you do that and don't get reception in 5-10 minutes, I would guess that the battery is not the issue.

Your present position doesn't help the unit, without more data. In order to find the satellites, it needs to know, in addition to where your are, where in the sky they are and they are constantly moving. Having the present position does help speed up acquistion. The 90 has an internal almanac / table that tells it where they will be at every minute during every day of the month. There are new algorithms to do this, but the old ones are crude and slow and the 90 has slower processors. It will take the 90 a LONG time to find them with a bad date/time. I kinda of think that 30 minutes would be enough to find one satellite. Once it finds one, it grabs the date/time from it.

Larry
 
Last edited:
Just wondering what antenna you're using? I have a -90B in my -9 (and quite like it) but it came with a GA35 antenna - and those are reported to have a known oscillatory failure mode.

The only other thing I could suggest, is to pull it and the antenna, and make a short pigtail to connect the antenna to the unit with power applied on your back deck to see if it works then. I was adamant I hadn't made a mistake with mine, but after not finding satellites in the plane, but it did at home made me double-check the coax, and sure enough, there was but one strand of the **** thing creating an intermittent short so it'd test OK when held 'just so' but fail in the 'as installed' position.

For a bad battery, I would think you'd get the "RCVR Hardware Error 0008" fault before you'd need to consider getting too deep into troubleshooting it.
 
I also have the KLN-90B. Never seen that indication. Is the database up to date? Can you even update the database anymore? I know mine is expired.
 
KLN-90B TROUBLESHOOTING ISSUE

Hello Gents

Sorry for the late reply but I've been busy flying the friendly sky at work..

I really do appreciate you guys taking the time to help me out in this.

Larry, as far as I can remember it is showing the right time and date but I would check next time at the hangar to make sure..

KR: My present antenna if my memory serve me right is a Comant 420..something and also tried it with a Garmin GA-56 I had in stock with no change.

Jim: The database is up to date as off yesterday and will update it with the new release first chance I get.

If you have more ideas, please let me know and I will report any new developpement

Thanks again

Bruno
[email protected]
 
Larry, as far as I can remember it is showing the right time and date but I would check next time at the hangar to make sure..
[email protected][/email]

The battery really just keeps the date/time and present position at shutdown. If your observation is correct, the battery isn't your issue.

Larry
 
KLN-90B TROUBLESHOOTING ISSUE

Hi Larry

I checked today and the Date& Time were accurate so as you say, the internal battery appears to be out of the equation..

I will put a battery charger on the a/c and turn the GPS ON and let it search for satellites for a long time and see if it can acquire them again..If not I guess it will become a boat anchor..:eek:

Thanks

Bruno
 
Last edited:
Bendix King KLN 90B track up, not north up

I am posting this on the chance that someone can help me. I am building an RV-10, but my question has to do with the Bendix King KLN 90B GPS that I have in my Mooney. Can anyone tell me how to change the GPS to show track up, not north up.
 
I am posting this on the chance that someone can help me. I am building an RV-10, but my question has to do with the Bendix King KLN 90B GPS that I have in my Mooney. Can anyone tell me how to change the GPS to show track up, not north up.

Here is how you do that:

First place Both screens (left/right) into SuperNav. (I hope you know what that means, but basically, if you have a course DIRECT to some point…. place the left screen onto screen 5, and then the right screen onto screen 5…and the entire display will become one large view.)

Afterwards, press the Right Cursor-button …and a small screen will appear upper-right…and that screen will allow you to use the large and small/right knobs to activate certain options for display along your course…. such as “VOR”… if you want all VORs to display then select TLH (Terminal, Low, High VORs) and rotate the knob to “Yes’….and they will display.
The next line will enable NDBs.
The third line will enable Airports.
The fourth line will allow you to select N up, DTK, or Track up.

Depress the right cursor button again to disable the cursor….and you are finished.

HOpe this helps.
 
Last edited:
Hello Gents

I have a vintage King KLN-90B installed in my RV-4 and I have a bit of a snag with it and was wondering if someone here familiar with these old GPS would have a clue on what could be the problem..

it looks like that it is no longer seeing the satellites or at least it doesn?t after 1/2 hrs and I?m getting a ??FLAG?? annunciation when in the NAV window.

I tried a different antenna, made sure the coax was good, enter a present position just to give it a head start in finding where it is etc...but it still doesn?t appear to see the satellites...

In the ??STA+1?? window where you see the satellites it is looking at all I get are ??00?? for SNR & ELV ... After 1/2 hr today I had 1 or 2 satellites that were showing some sort of SNR ( Sound to Noise ) and elevation but that was it...

Any idea what might be the problem??

I?m thinking that the internal memory battery is either dead or very weak and the GPS has to find where it is every time it boot up and it takes a long time.. Am I right on this...??

If so, how hard is it to replace the battery if someone has ever done it??

Thank you for any info you may provide.

Bruno
[email protected]

Technically this should only be done by an avionics station…but here’s how to do it.
Remove the data cartridge.

Make certain you are discharged (you aren’t full of static electricity).

REmove the bottom cover. Remove the screws which hold the bottom PC boatrd. Be careful to note the orientation of the flat-cables and individual wires as you pull that bottom PC board out…because you want to reinstall it the same way.

OPening the PCboard like a book…you can now view the main board and the Pink battery. See the pics I posted.

The Battery is the size of an AA battery, but has two leads, one on each end.
The Mx Manual instructs that it must be soldered to the PC main board….but that is not what most techs do….. they clip the leads AT the old battery…leaving the old batterrys’ leads soldered to the PC board.
Now all that is necessary is to remove the battery from it’s mounting clips….and install the new battery… soldering the new batterys’ leads directly to the still-existing leads from the removed battery.

Put it back together. ReInstall the database.

When you turn the unit back on….you may have to re-initiate the unit for date, Zulu time, etc. …and let it acquire the Almanac of satellites.

Afterwards, it should navigate again.

Using this method, your personal memorized waypoints will be lost because you did not keep the unit powered during the batt replacement. So if your batt hasn’t already died (sounds like yours has)…then you’ll have to re-insert them into memory.

HOpe this helps.

The battery can be found online: https://www.amazon.com/TADIRAN-BATT...nics&sprefix=tl-5104/p,electronics,221&sr=1-1
 

Attachments

  • IMG_1973.jpeg
    IMG_1973.jpeg
    31 KB · Views: 23
  • IMG_1972.jpeg
    IMG_1972.jpeg
    42.5 KB · Views: 19
  • IMG_1974.jpeg
    IMG_1974.jpeg
    21.9 KB · Views: 13
Back
Top