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Repair of King luminescent / gas discharge displays, and LED replacements

Any recommendations for a shop to fix the display on my KAP150 autopilot? The unit works ok but recently, after some avionics upgrading, the display has become erratic with many modes not illuminating at all, even though they’re working.

I’d heard King are no longer offering to supply parts to repair, rather offer only complete replacement. Does this rule out any “fix” at all in the UK other than replacement?

First Q is whether you need an EASA-1 form (necessary for a fully official job on an EASA reg aircraft) or indeed any form at all. If you are N-reg then you don’t need the 8130-3 either (contrary to popular belief). Or you may be happy with a repair “off the books” in which case some little avionics repair shop in a wooden shed may be able to do it. Most of the King display issues are corrosion in the display connector and the display itself is fine. I know a “shop in a wooden shed” which seems to spend most of its time repairing these connections… but no paperwork of course

Administrator
Shoreham EGKA, United Kingdom

I’ve noticed some of the segments on my KN 64 DME LCD display have started to become unreliable. Is this likely to be a corrosion thing too?

EIWT, Ireland

My DME display failed on a 3 hour trip yesterday. It’s a KN62. It is showing the number 8 on the extreme left and you can see a sweeping across the rest of the display.

It looked like the classic issue with dodgy contacts on the gas discharge display to the plug below but cleaning the contacts and switch cleaner has not worked. The display is bright so it’s not the issue with the LDR (light dependent resistor) on the front panel going open circuit. The LDR is in excellent condition.

Is @Simon around and does he still work for Nav Com Avionics or has he moved? If you get this Simon can you PM me?

After the bank holiday I will be on the phone to Nav Com as they were one of the few places in the UK who could do proper repairs. Does anybody else have any recommendations in the UK? I also thought about Avionik Straubing as I have used them before but the DHL’s both way gets a bit expensive.

United Kingdom

Simon has like no gone from Nav/com, unfortunately like so many long term employees the managment treated him like part of the furniture and when he found out that they had employed a semi skilled guy and paid him considerably more he quit.

We did offer him the opportunity to start his own radio workshop but our base is too far from his home to make this a realistic proposition for him. The loss of his skills are a real blow to GA and a demonstration of just how badly some companies are managed.

Navcom repaired a few bits for me a while ago. They were blocked by Honeywell from doing these in the future, apparently, due to something to do with this. Their top guy was Ted Honey but I believe he’s long gone. They issued an EASA-1 form with “Airtime” on top of it, which I thought was really funny

I was also that King withdrew the LED replacement option, or maybe EASA made it impossible to install it.

Administrator
Shoreham EGKA, United Kingdom

So what causes these King displays to fail? I have read some past posts about arcing and conductivity building up between the tracks but this one has been cleaned with switch cleaner and still does not work.

The displays are as rare as hens teeth now and even “chop shops” are running out. My DME is off for a proper repair shop but I’m interested from a theoretical point of view.

There is a stub of glass on the back where the Neon gas went in and the hermetic seal was made. If the failure mode was loss of gas, you would think that some Chinese entrepreneur would drill out the rear stub with a 1 mm drill and introduce gas and epoxy the seal.

Perhaps it’s not loss of gas – over to the very informed forum…………….

United Kingdom

I guess a great many readers will be interested in the answer and a solution!

UK, United Kingdom

The main reason why these DME’s have a dim display is that there is a Light Dependent Resistor which breaks down at the front of the unit. You can get LDR’s for 10 pence each and it can be soldered in to the pins of the existing unit.

I am hoping that my unit has a good display but there is a power supply issue. Perhaps recent disuse has caused an Electrolytic capacitor to fail. We’ll see what the repair shop comes up with.

United Kingdom

The usual reason for failure is usualyas stated inthe first post, arcing promoted by conductivity between the tracks . The other thing that causes problems is the fact unit that drives them fails.

If it is the drive unit it can be fixed in the UK but the problem comes when the display ( having been cleaned three or four times ) finally quits and the unit has to return to BK to have a Liquid crystal display fitted at huge cost.

As to why they finally fail to respond to cleaning, I don’t know the answer to that.

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