Avidyne Homepage
Forum Home Forum Home > Avidyne General > IFD 5 Series & IFD 4 Series Touch Screen GPS/NAV/COM
  New Posts New Posts RSS Feed - auto dimming on 540 vs 440
  FAQ FAQ  Forum Search   Register Register  Login Login

auto dimming on 540 vs 440

 Post Reply Post Reply
Author
Message
chflyer View Drop Down
Senior Member
Senior Member
Avatar

Joined: 24 Jan 2013
Location: LSZK
Status: Offline
Points: 569
Post Options Post Options   Thanks (0) Thanks(0)   Quote chflyer Quote  Post ReplyReply Direct Link To This Post Topic: auto dimming on 540 vs 440
    Posted: 04 Aug 2018 at 4:53pm
I'm sure this has been beaten to death during the lighting parameters discussions in different threads, but I can't quickly find the answer. Perhaps someone can point me in the right direction before I start playing with the setup and maintenance settings.

I have an IFD540 immediately above an IFD440 in my C172 panel. Both have lighting configured exactly the same, using default parameters. I haven't changed a thing.

The 440 is always clearly readable, regardless of ambient lighting conditions. The 540 is always dimmed and not nearly so easy to read. Why the difference? The ambient cockpit lighting doesn't change the relationship. It is the same whether I'm in the cockpit in the dark in the hanger or out in the sun.

What could be the explanation?
Vince
Back to Top
compasst View Drop Down
Groupie
Groupie


Joined: 22 Feb 2015
Status: Offline
Points: 99
Post Options Post Options   Thanks (0) Thanks(0)   Quote compasst Quote  Post ReplyReply Direct Link To This Post Posted: 25 Aug 2018 at 9:13pm
As a data point - I have had the IFD 540 since it was released. I have always had it set for auto dimming. Initially, that worked flawlessly. Around the time of 10.2 release, the dimming became flaky. Sometimes it worked, sometimes it didn't, sometimes it was so dim as to be not usable. Sometimes it changed as I moved the airplane's panel light control (still set on auto dimming). Talked with tech support - got nowhere. For the past several months, it has been mostly working on auto OK. Nothing was changed in my installation - just the 10.2 upgrade.
Back to Top
doog View Drop Down
Newbie
Newbie


Joined: 27 Nov 2017
Location: KCCR
Status: Offline
Points: 4
Post Options Post Options   Thanks (0) Thanks(0)   Quote doog Quote  Post ReplyReply Direct Link To This Post Posted: 26 Aug 2018 at 6:58pm
I thought I was the only one...  I switched to manual brightness setting.  10.2.1

Back to Top
wb8wka View Drop Down
Newbie
Newbie


Joined: 06 Jul 2018
Location: Holland MI
Status: Offline
Points: 6
Post Options Post Options   Thanks (0) Thanks(0)   Quote wb8wka Quote  Post ReplyReply Direct Link To This Post Posted: 30 Aug 2018 at 4:18pm
I've got a new install and mine is quite flakey.

I went to manual mode and noticed a big difference in lighting at a certain point. Here is the video of it below

https://youtu.be/6voJq4OZQg4

Is this a software bug or some kind of hardware issue? And yes, it really is changing that much, not a video artifact. My sensor doesn't seem to be responding either. 


Edited by wb8wka - 30 Aug 2018 at 4:18pm
Back to Top
chflyer View Drop Down
Senior Member
Senior Member
Avatar

Joined: 24 Jan 2013
Location: LSZK
Status: Offline
Points: 569
Post Options Post Options   Thanks (0) Thanks(0)   Quote chflyer Quote  Post ReplyReply Direct Link To This Post Posted: 31 Aug 2018 at 10:06am
I gave up and did the same as doog, i.e. changed the setting to custom/manual & max. I'll adjust again manually if I need to turn it down for some reason. Given the other comments, it sounds like there is a real issue with the IFD540 though.
Vince
Back to Top
ChainSaw View Drop Down
Newbie
Newbie
Avatar

Joined: 28 May 2018
Location: CA
Status: Offline
Points: 27
Post Options Post Options   Thanks (0) Thanks(0)   Quote ChainSaw Quote  Post ReplyReply Direct Link To This Post Posted: 01 Sep 2018 at 9:30pm
Curious sequence of events after selecting auto dim on the ifd 440 in PA28RT201 Arrow IV:
1. Set auto dim at night ( display was blinding)
2. The very next daylight sortie experienced a burnt out  'radio/NAV light' potentiometer and possibly the transistor on the Piper switch panel (left most thumbwheel). This happened during taxi after turning on the NAV lights which are controlled by a thumbwheel knob that drives a potentiometer that also dims the radio/instrument lights.
This would be the potentiometer/ thumbwheel that dim the ifd440 if it is connected and set to dim with the instrument lights.
3. The NAV lights (red and green) on wing tips no longer work.
Potentiometer and/or the transistor on the switch panel are clearly blown.

Coincidence?

Could the ifd 440 display be drawing more current in the daytime than this dimmer switch was ever designed for?

Any thoughts are greatly appreciated.

Thanks.


Edited by ChainSaw - 01 Sep 2018 at 9:36pm
Back to Top
DavidBunin View Drop Down
Senior Member
Senior Member
Avatar

Joined: 20 May 2015
Location: Rockwall, TX
Status: Offline
Points: 726
Post Options Post Options   Thanks (0) Thanks(0)   Quote DavidBunin Quote  Post ReplyReply Direct Link To This Post Posted: 02 Sep 2018 at 12:43pm
I think the IFD units don't actually take any meaningful amount of power (current flow) from the dimming circuit.  I believe the display and bezel backlights are actually energized from the internal IFD power supply.  It just takes a voltage sample from the aircraft's lighting circuit to decide how bright to make everything.

Sorry to say, but I think your circuit fault is external to the IFD.
Back to Top
MysticCobra View Drop Down
Senior Member
Senior Member
Avatar

Joined: 29 Jan 2013
Status: Offline
Points: 495
Post Options Post Options   Thanks (0) Thanks(0)   Quote MysticCobra Quote  Post ReplyReply Direct Link To This Post Posted: 02 Sep 2018 at 1:50pm
Originally posted by ChainSaw ChainSaw wrote:

Curious sequence of events after selecting auto dim on the ifd 440 in PA28RT201 Arrow IV:
1. Set auto dim at night ( display was blinding)
2. The very next daylight sortie experienced a burnt out  'radio/NAV light' potentiometer and possibly the transistor on the Piper switch panel (left most thumbwheel). This happened during taxi after turning on the NAV lights which are controlled by a thumbwheel knob that drives a potentiometer that also dims the radio/instrument lights.
This would be the potentiometer/ thumbwheel that dim the ifd440 if it is connected and set to dim with the instrument lights.
3. The NAV lights (red and green) on wing tips no longer work.
Potentiometer and/or the transistor on the switch panel are clearly blown.

Coincidence?

Could the ifd 440 display be drawing more current in the daytime than this dimmer switch was ever designed for?

Any thoughts are greatly appreciated.

Thanks.
If your IFD is tied in to the Piper dimming circuit, then that might a bad situation.  My installer wired mine up that way, and I ended up burning up 3 IFDs before we finally figured out what was going on.  Once we got it figured out, my installer added a separate dimmer to my panel just for avionics backlighting, and everything's been good ever since.  

I thought the installation manual was updated with notes about that after my experience (I was an early adopter), but since the install manuals have been removed from public access, I can't confirm that.

I have a '73 PA28-180; I'm not sure if the dimming circuit is the same as your plane.


Edited by MysticCobra - 02 Sep 2018 at 1:51pm
Back to Top
ChainSaw View Drop Down
Newbie
Newbie
Avatar

Joined: 28 May 2018
Location: CA
Status: Offline
Points: 27
Post Options Post Options   Thanks (0) Thanks(0)   Quote ChainSaw Quote  Post ReplyReply Direct Link To This Post Posted: 02 Sep 2018 at 4:39pm
Hmm.... I think Mystic Cobra is closer to the root cause of the burnt NAV/radio light dimmer with the ifd 440 on auto dim in daylight. When my A&P fixes the dimmer potentiometer and transistor, we will have little choice but to test the system holistically. If the replacement parts blow or the ifd doesn't work, we will have a much better idea of where to start troubleshooting. The installer of the ifd440 is not likely to give us a straight answer, based on previous experience. We will have to figure it out ourselves . TM Mystic Cobra.

Edited by ChainSaw - 02 Sep 2018 at 4:44pm
Back to Top
ChainSaw View Drop Down
Newbie
Newbie
Avatar

Joined: 28 May 2018
Location: CA
Status: Offline
Points: 27
Post Options Post Options   Thanks (0) Thanks(0)   Quote ChainSaw Quote  Post ReplyReply Direct Link To This Post Posted: 02 Sep 2018 at 5:32pm
Mystic Cobra, when your dimmer was burning up three ifds, was the main power to the ifd connected through the dimmer, or was the dimmer connected to some dimmer sensing input on the ifd?  The former would clearly be a problem for a power controlled device since the current draw would be inversely proportion to the voltage, assuming the voltage decreased somehow with tthe dimmer wheel or transistor that is in the Piper switch panels and dimmer circuit. P=V*I.

Edited by ChainSaw - 02 Sep 2018 at 5:44pm
Back to Top
Bob H View Drop Down
Groupie
Groupie


Joined: 26 Jan 2018
Location: NH - KMHT
Status: Offline
Points: 91
Post Options Post Options   Thanks (0) Thanks(0)   Quote Bob H Quote  Post ReplyReply Direct Link To This Post Posted: 02 Sep 2018 at 5:45pm
Originally posted by MysticCobra MysticCobra wrote:

If your IFD is tied in to the Piper dimming circuit, then that might a bad situation.  My installer wired mine up that way, and I ended up burning up 3 IFDs before we finally figured out what was going on.  Once we got it figured out, my installer added a separate dimmer to my panel just for avionics backlighting, and everything's been good ever since.  

I thought the installation manual was updated with notes about that after my experience (I was an early adopter), but since the install manuals have been removed from public access, I can't confirm that.

I have a '73 PA28-180; I'm not sure if the dimming circuit is the same as your plane.
So, what exactly is the root cause of the burn out?  What was the incompatibility and why?  For ChainSaw to see if the "...replacement parts blow or the ifd doesn't work...", is not a practical or effective troubleshooting technique especially if the IFD gets bricked.  A good avionics technician ought to be able to troubleshoot it without blowing things up.
Bob
Back to Top
ChainSaw View Drop Down
Newbie
Newbie
Avatar

Joined: 28 May 2018
Location: CA
Status: Offline
Points: 27
Post Options Post Options   Thanks (0) Thanks(0)   Quote ChainSaw Quote  Post ReplyReply Direct Link To This Post Posted: 02 Sep 2018 at 5:57pm
completely agree about not using the ifd or the new parts as expensive fuses. However, we may not have access to ' the good Avionics technician' if you follow my meaning. If the root cause is anything other than worn out parts in the switch panel (pot and transistor) we are in for an expensive episode. We will not be able to troubleshoot back to the ifd or ifd connections/previously known ifd dimmer connections 'do's and dont's' on this issue.
Back to Top
ChainSaw View Drop Down
Newbie
Newbie
Avatar

Joined: 28 May 2018
Location: CA
Status: Offline
Points: 27
Post Options Post Options   Thanks (0) Thanks(0)   Quote ChainSaw Quote  Post ReplyReply Direct Link To This Post Posted: 02 Sep 2018 at 6:13pm
That being said... Please point us to any specific Avidyne IFD documentation that prevents the 3x ifd burn-out episodes that Mystic Cobra described. At least I can take that to the avionics tech and ask, '' Did you connect the ifd like this...'? Then, I am at the mercy of the techs availability and memory. Otherwise, I am heading blindly down the same path as MysticCobra with no information to prevent the same episode.
Back to Top
brou0040 View Drop Down
Senior Member
Senior Member


Joined: 13 Dec 2012
Status: Offline
Points: 584
Post Options Post Options   Thanks (0) Thanks(0)   Quote brou0040 Quote  Post ReplyReply Direct Link To This Post Posted: 02 Sep 2018 at 8:41pm
I fried a few IFDs with the dimming circuit in my 182 as well.  Eventually the shop traced it back to a "improperly manufactured pin" but I'm pretty sure they hooked up the dimmer lines backwards because it would work fine for a long time and as soon as I flew at night and used the dimmer, it would fry.

There are separate lighting bus and aircraft power pins.
Back to Top
Bob H View Drop Down
Groupie
Groupie


Joined: 26 Jan 2018
Location: NH - KMHT
Status: Offline
Points: 91
Post Options Post Options   Thanks (0) Thanks(0)   Quote Bob H Quote  Post ReplyReply Direct Link To This Post Posted: 02 Sep 2018 at 10:46pm
Originally posted by ChainSaw ChainSaw wrote:

That being said... Please point us to any specific Avidyne IFD documentation that prevents the 3x ifd burn-out episodes that Mystic Cobra described. At least I can take that to the avionics tech and ask, '' Did you connect the ifd like this...'? Then, I am at the mercy of the techs availability and memory. Otherwise, I am heading blindly down the same path as MysticCobra with no information to prevent the same episode.
Well, I’m not an avionics technician, but the approach I would take would be something along these lines:
1. Repair the aircraft dimming circuit and make sure it works without the IFD connected.
2. Determine the aircraft dimming circuit's type of operation:
      a.  Varying duty-cycle?
      b.  Varying voltage from low to high?
            i.  Determine minimum voltage and maximum voltage being output
      c.  Other?
3. Determine maximum power output capability of aircraft dimming circuit
4. Determine maximum power being drawn by aircraft circuit without IFD connected
5. Determine IFD input requirements for auto dimming.  Is this compatible with aircraft dimming circuit based on above determined parameters?
6. Ensure auto dimming wires are connected properly to IFD pins, but do not connect into aircraft’s dimming bus yet.
7. Based on #5 above being yes, connect a simulated IFD load on aircraft dimming circuit and determine if dimming works as expected.
8. Based on #5 above, connect a simulated dimming input to the IFD and determine if it behaves properly.  Monitor/Control power input (voltage & current) to ensure limits are not exceeded.
9. Based on the above results and information, decide what steps are next.

Do NOT take the above as a comprehensive step by step approach on how to resolve your problem.  I am merely trying to show that there is much that can be done before just wiring it up, crossing your fingers, and hoping nothing burns up.  The above is how I would begin to systematically think through the logical steps, but I would do a lot more thinking to ensure I’ve got everything worked out.

Bob
Back to Top
ChainSaw View Drop Down
Newbie
Newbie
Avatar

Joined: 28 May 2018
Location: CA
Status: Offline
Points: 27
Post Options Post Options   Thanks (0) Thanks(0)   Quote ChainSaw Quote  Post ReplyReply Direct Link To This Post Posted: 02 Sep 2018 at 11:38pm
Do avionics techs typically perform the load simulating you described before they connect an ifd? I am sure that my installer did not.  I can't wait to hear what you are posing for  the  'simulated loads' for (7) and(8) in your previous thread. The IFD is likely to be a capacitive load, not purely resistive - characteristic of electrical loads for computers And radio circuits. Capacitive load bank? Heat sinks? Surely you didn't envision a resistor that you would hold with your fingers for this test? Then, put your two simulated load devices across the connections of the Piper switch panel... Don't try this at home or in your airplane.... Please make a reference to a connection diagram for the ifd pins in question.

Thanks, but no thanks.


Edited by ChainSaw - 03 Sep 2018 at 12:31am
Back to Top
MysticCobra View Drop Down
Senior Member
Senior Member
Avatar

Joined: 29 Jan 2013
Status: Offline
Points: 495
Post Options Post Options   Thanks (0) Thanks(0)   Quote MysticCobra Quote  Post ReplyReply Direct Link To This Post Posted: 03 Sep 2018 at 12:31am
Originally posted by ChainSaw ChainSaw wrote:

Mystic Cobra, when your dimmer was burning up three ifds, was the main power to the ifd connected through the dimmer, or was the dimmer connected to some dimmer sensing input on the ifd?  The former would clearly be a problem for a power controlled device since the current draw would be inversely proportion to the voltage, assuming the voltage decreased somehow with tthe dimmer wheel or transistor that is in the Piper switch panels and dimmer circuit. P=V*I.
The main power was not connected through the dimmer; main power always came from a dedicated feed from the avionics bus.  I did see the wiring diagrams when we were t/s this issue, but it was a long time ago; if I recall correctly, the IFD has a dimmer high pin and dimmer low pin. 

I could be wrong about this, but I think the IFD expects the dimmer low pin to essentially be ground, and the dimmer high pin to vary from 0 to 5/14/28V.  I think the Piper "dimmer low" is not always 0V, and that caused bad things to happen inside the IFD.


Edited by MysticCobra - 03 Sep 2018 at 9:32am
Back to Top
ChainSaw View Drop Down
Newbie
Newbie
Avatar

Joined: 28 May 2018
Location: CA
Status: Offline
Points: 27
Post Options Post Options   Thanks (0) Thanks(0)   Quote ChainSaw Quote  Post ReplyReply Direct Link To This Post Posted: 03 Sep 2018 at 12:38am
Thank you Mystic Cobra. Did any other electrical components, other than the ifds, get damaged during the three episodes you described? For instance, did you have to replace any of the potentiometers or transistors (2 each) in the Piper switch panel when the ifds were blowing due to dimmer connections?
Back to Top
MysticCobra View Drop Down
Senior Member
Senior Member
Avatar

Joined: 29 Jan 2013
Status: Offline
Points: 495
Post Options Post Options   Thanks (0) Thanks(0)   Quote MysticCobra Quote  Post ReplyReply Direct Link To This Post Posted: 03 Sep 2018 at 1:38am
Originally posted by ChainSaw ChainSaw wrote:

Thank you Mystic Cobra. Did any other electrical components, other than the ifds, get damaged during the three episodes you described? For instance, did you have to replace any of the potentiometers or transistors (2 each) in the Piper switch panel when the ifds were blowing due to dimmer connections?
No, in my case the only damaged component was the IFD itself.  I would typically catch an occasional light whiff of electrical smoke, then over time, increasingly stronger/more frequent whiffs, and then eventually:  Zzzzot.  In hindsight, those whiffs might have been related to me dialing up the inst panel brightness as the sun was going down (light scent when dim, stronger scent as lighting came up), but the smoke smells didn't come immediately after fiddling with the dimmer, so I never made that connection when it was happening.


Edited by MysticCobra - 03 Sep 2018 at 1:39am
Back to Top
Bob H View Drop Down
Groupie
Groupie


Joined: 26 Jan 2018
Location: NH - KMHT
Status: Offline
Points: 91
Post Options Post Options   Thanks (0) Thanks(0)   Quote Bob H Quote  Post ReplyReply Direct Link To This Post Posted: 03 Sep 2018 at 8:59am

Originally posted by ChainSaw ChainSaw wrote:

Do avionics techs typically perform the load simulating you described before they connect an ifd? I am sure that my installer did not.  I can't wait to hear what you are posing for  the  'simulated loads' for (7) and(8) in your previous thread. The IFD is likely to be a capacitive load, not purely resistive - characteristic of electrical loads for computers And radio circuits. Capacitive load bank? Heat sinks? Surely you didn't envision a resistor that you would hold with your fingers for this test? Then, put your two simulated load devices across the connections of the Piper switch panel... Don't try this at home or in your airplane.... Please make a reference to a connection diagram for the ifd pins in question.

 

Thanks, but no thanks.

No, avionics techs don’t normally do what I described, but then boxes and circuits don’t normally burn up when simply being connected.  In the absence of root cause information, a modicum of caution and analysis is in order prior to just hooking things up.  I’m merely suggesting an alternative approach.  By stepping through 1 to 6, no further action may even be necessary, especially with MysticCobra’s additional insight.  Your only proposal to date was to just hook things up and hope, but that didn’t stop you from being snarky when someone was only trying to help with an alternative approach.  You even made up load scenarios with which to criticize with “Don’t try this at home or in your airplane”.  You don’t have to agree with or accept advice that you receive here on the forum, but if you ask for help don’t bash those who try.

Bob
Back to Top
ChainSaw View Drop Down
Newbie
Newbie
Avatar

Joined: 28 May 2018
Location: CA
Status: Offline
Points: 27
Post Options Post Options   Thanks (0) Thanks(0)   Quote ChainSaw Quote  Post ReplyReply Direct Link To This Post Posted: 04 Sep 2018 at 11:31am
No worries.  Point being is that installing the simulated electrical  load  in an an aircraft electrical system poses more danger than  ringing out harnesses in the usual manner and connecting the ifd - what most installers do.  The others in this thread describe what installers and users actually experience  in practice. Avidyne units apparently failed safe in these common situations and did not cause electrical system damage or fires, even with the problematic dimmer design described in this thread. Avionics techs/installers, with the  possible exceptionon of Avidyne, are not likely to build a fail safe, simulated electrical load. The  simulated  electrical load was not a good suggestion.

Edited by ChainSaw - 04 Sep 2018 at 3:50pm
Back to Top
Bob H View Drop Down
Groupie
Groupie


Joined: 26 Jan 2018
Location: NH - KMHT
Status: Offline
Points: 91
Post Options Post Options   Thanks (0) Thanks(0)   Quote Bob H Quote  Post ReplyReply Direct Link To This Post Posted: 04 Sep 2018 at 9:38pm
Originally posted by ChainSaw ChainSaw wrote:

No worries.  Point being is that installing the simulated electrical  load  in an an aircraft electrical system poses more danger than  ringing out harnesses in the usual manner and connecting the ifd - what most installers do.  The others in this thread describe what installers and users actually experience  in practice. Avidyne units apparently failed safe in these common situations and did not cause electrical system damage or fires, even with the problematic dimmer design described in this thread. Avionics techs/installers, with the  possible exceptionon of Avidyne, are not likely to build a fail safe, simulated electrical load. The  simulated  electrical load was not a good suggestion.
Glad you got it all figured out.  Good luck.
Bob
Back to Top
ChainSaw View Drop Down
Newbie
Newbie
Avatar

Joined: 28 May 2018
Location: CA
Status: Offline
Points: 27
Post Options Post Options   Thanks (0) Thanks(0)   Quote ChainSaw Quote  Post ReplyReply Direct Link To This Post Posted: 04 Sep 2018 at 10:13pm
Thank you. Glad I could help.
Back to Top
 Post Reply Post Reply
  Share Topic   

Forum Jump Forum Permissions View Drop Down

Forum Software by Web Wiz Forums® version 12.01
Copyright ©2001-2018 Web Wiz Ltd.

This page was generated in 0.055 seconds.