King KT74

[carusoam]

Neil,

1) Could it be a 12v vs 24v issue?  The display thinks it is running on 24v, but is actually running on 12v?

Something to ask the BK guys when you talk with them again...

2) I would think that the baseline display brightness needs to be adjustable through a menu setting.  This is expected because the BK displays of yesterday won't be able to match the KT74 display of today...

Got any photos?

Best regards,

-a-

[neilpilot]

22 minutes ago, carusoam said:

1) Could it be a 12v vs 24v issue?  The display thinks it is running on 24v, but is actually running on 12v?

Unlikely.  The unit will run on 11v-33v and there's no specifics to differentiate the insallation, nor a user function to specify aircraft voltage spec

2) I would think that the baseline display brightness needs to be adjustable through a menu setting.  This is expected because the BK displays of yesterday won't be able to match the KT74 display of today...

I was surprised to find that baseline brightness display was not user-adjustable, but BK and Trig support both indicated that it was not.

Got any photos?

Only one, attached below.

Best regards,

-a-

 

[thinwing]

Maybe unit position on panel ,but my kt74 is brighter than that even in direct sunlight

[neilpilot]

Here are a couple of better pics taken this morning on way to KNEW.

[Oldguy]

Mine seems to show up well and is easily readable.

(Pay no attention to the extra holes in the panel.)

 

[ArtVandelay]

Here are a couple of better pics taken this morning on way to KNEW.

That's not even direct sunlight, an interesting test would be to pull the unit and just hook up the power (12v) and nothing else and see what the display looks like, if bright then it is an installation problem.

[OR75]

2 hours ago, neilpilot said:

Here are a couple of better pics taken this morning on way to KNEW.

 

something is off:

the warranty exchange did not make any difference

I am surprised the shop that did  the job would sign off on it

[neilpilot]

5 hours ago, teejayevans said:

That's not even direct sunlight, an interesting test would be to pull the unit and just hook up the power (12v) and nothing else and see what the display looks like, if bright then it is an installation problem.

That might be interesting but, unlike a navcom, that's not owner approved. I could pull the unit but not re-install.

[neilpilot]

6 hours ago, Hyett6420 said:

Is his a replacment of the one you had in september last year?  If not, i would suggest the light sensor or light sensor circuit is buggered. 

If not done already, get a replacement unit and have them install it.

Not sure I understand you comment. The first KT74 replaced a KT76A in October, after the Mooney Summit. That was exchanged for the one in the photo in Dec, in a failed attempt to improve the display.

[jlunseth]

I have one.  What can I say, works good.  I do recall there was a little extra wiring to get the GPS signal in.  I think I am just going to turn my TIS-A off.  It displays on the 430AW and when it "sees" approaching traffic it pops up a tiny screen to display it, which is an annoyance and blocks the main display.  I also get a verbal notice in my headset when the TIS-A signal fails.  It doesn't fail that often, but again, it is an annoyance.  TIS-A is just a small subset of what is available, ADS-B is better.  I have a Stratus 2 so when I want traffic I get a much better and more complete traffic display on my iPad, thanks to the ADS-B Out from the KT74.

The KT74 is mandate compliant (if it has the GPS signal input).

I don't have any issues at all with the display, mine is plenty bright, but it is over on the co-pilot side so I am not staring at it all of the time.  I remember there was a little bit of set up which was easy, but since then I have two interactions with it.  One, I key in my squawk code when I get one.  Two, I hit VFR when I want to clear the code and squawk VFR.  Oh, and three, I hit Ident when ATC asks.  Other than that, it has some other functions but I would rather fly.  I have messed with them and don't recall that they were thrilling.

[thinwing]

Only thing I can think of is installer is using your dimbus for display brightness rather than built in photocell...your pic shows a really dim display like it's on night setting..

[neilpilot]

 

5 hours ago, thinwing said:

Only thing I can think of is installer is using your dimbus for display brightness rather than built in photocell...your pic shows a really dim display like it's on night setting..

When I operate overhead map light dimmer, there's no effect on KT74.  When I cover the photocell with my finger (night simulation) the display does get even dimmer.

[thinwing]

Ok..I don't have install manual in ft of me..I will check tommorrow

[neilpilot]

On ‎2‎/‎8‎/‎2017 at 10:35 PM, neilpilot said:

That might be interesting but, unlike a navcom, that's not owner approved. I could pull the unit but not re-install.

I have the opportunity to send my KT74 out for a bench comparison with another unit.  I don't think I'll gain anything from this exercise, since I've already done an exchange that appears equally as "dim" and that probably points to some installation issue.  However, am I correct in thinking that a non-A&P owner is NOT permitted to remove, and then re-insert, a transponder?

[Andy95W]

24 minutes ago, neilpilot said:

  However, am I correct in thinking that a non-A&P owner is NOT permitted to remove, and then re-insert, a transponder?

Yes, but you wouldn't be the first one to do so.  Or the last.

[carusoam]

How does the box handle the 12/24 v question?

does the display know it is running on 12V?

Does it get a resistor removed during installation?

Something simple isn't right.  Like a 24V bulb lighting a 12V installation...

PP guesses, not an instrument guy...

Best regards,

-a-

[carusoam]

Some radios are three or so different electronics in one metal box. Often a 24V line may enter the box on a number of wires.  An old nav/com is often two distinctly different radios in one box...

a wiring diagram for the plugs at the back of the radio would indicate how the radio is supposed to be wired.

a 12V line going to the proper transmitter node will work well.  If there are two nodes to supply the display and 12V is supplied to a 24V node.  It would be dark, yet work properly.

Good idea to check what the plug wiring diagram looks like.

BK radios today are built by several sub-suppliers, this is starting to make sense to me....

Still just a guess on my part.

Best regards,

-a-

Edited February 17, 2017 by carusoam

[ArtVandelay]

Would this not manifest itself in weaker transmissions as well?

Modern electronics use voltage regulation to step down 24 or 12 to 5v, which is used to power the electronics, search for LM7805, IIRC the 74 (and probably most other) have a pin it uses that is fed by the dimmer and will dim based on the voltage or current passing through this special circuitry, I've seen 2 separate pins to handle the 12/24.

[neilpilot]

6 hours ago, teejayevans said:

Modern electronics use voltage regulation to step down 24 or 12 to 5v, which is used to power the electronics, search for LM7805, IIRC the 74 (and probably most other) have a pin it uses that is fed by the dimmer and will dim based on the voltage or current passing through this special circuitry, I've seen 2 separate pins to handle the 12/24.

I still don't know why my KT74 appears dim (remember this is the 2nd one to appear dim).  I can confirm, based on what I'm told, 2 things.  First off, there's a single power supply input that's rated for 11-33v.  There is not resistor removal, wiring change or setup to change from 12v to 24v operation.  Secondly, in discussions with Bendix-King and the shop manager of another authorized installer, I can confirm that the KT74 does not connect to a separate dimmer circuit.  The dimming function is entirely internal to the unit, and controlled by the light sensor.  My light sensor is properly configured, and does dim (even more) when covered.  As previously mentioned, based on both BK and Trig user manuals and several discussions with customer service, the user is not able to configure the display brightness, only the night dimmer function.

I do understand that the TRIG version of the KT-74 is internally identical to the KT-74 EXCEPT for the display.

[OR75]

what does the shop that did the install say ?

 

[neilpilot]

They said "yes it looks dim", both before and after they installed the exchange unit

[ArtVandelay]

They said "yes it looks dim", both before and after they installed the exchange unit

Have they tried just hooking it up to 12v power supply on the bench? This should take them 5 minutes and if not dim would point to the installation.

[neilpilot]

1 minute ago, teejayevans said:

Have they tried just hooking it up to 12v power supply on the bench? This should take them 5 minutes and if not dim would point to the installation.

I don't know (partner flew up for the exchange), but that's a really good point.  I may call the shop Monday.

[OR75]

It looks to me that you are trying to do yourself (solve an issue if there is one because pictures can be misleading ) what the shop should be doing 

[neilpilot]

Just to put a close to this rather old thread, where I posted that my KT74 display was extremely dim to the point that it's difficult to read in sunlight...........after several return visits to my shop, including installation of an exchange unit, the display remained dim,

Recently we visited a different avionics shop.  The technician's initial response, after looking at my panel, was that "that's not right (i.e. too dim), and it needs to be either fixed or returned".  However, after that shop had many discussions with BK customer service, and they checked our installation, we were told that the KT74 was installed & working correctly.

Bottom line - I'm flying behind a new KT74 that works fine, except that the display is often too dim to read without using my hand to shade the display.  Based on my experience, I obvious cannot recommend the KT74.