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Garmin 430W Display Problems

larosta

Well Known Member
We have had a Garmin 430W in our aircraft for several years and it has become a treasured asset. Recently we began having problems with the display brightness. The problem is intermittent and all of the other functions seem to work fine even though the display does not. I would like to find out if others have seen similar symptoms and if so what the solution might have been.

* Several times, the display went to full brightness and contrast in daytime and became unreadable.
* Once, it went almost completely dark at night and also became unreadable.
* When it fails, the brightness changes gradually, not instantaneously, as if it was adapting to changing light conditions.
* When that happens, the brightness no longer reacts to changing light (e.g. covering the photocell does not reduce the brightness when it is at full bright, and shining a light at it in the dark does not increase the brightness).
* In each case, we were able to recover by switching the lighting from "auto" to manual and reducing/increasing the brightness and contrast values manually to a brightness and contrast close to "9999", their maximum.
* Restarting the unit in the air did not help (after restart, the unit goes back to "auto" lighting).
* However, after the plane has been sitting for a period of time the display operates normally for the next few flights.
* We have checked the avionics buss voltage and it is OK.
* We have checked the cooling air fan and it appears to be OK.

Thoughts, experiences, solutions, recommendations, etc. are welcome.

- larosta
 
I had one GNC-420 that had similar screen issues. The local Garman dealer could not repair it. Garmin's repair/recondition flat fee was about $1100+. Last year my second GNC-420 screen started going dim with warmer summer temperatures. Garmin offered a trade-in deal and I traded both and some $ to upgrade to a GTN-750Xi. I am very pleased with the ease of operating the GTN750 and its capabilities.

The incentive to replace my two GNC-420s was based on a Garmin seminar and tour at the factory that I attended in Olathe, KS. They said that they planned to support the Garmin 400/500 series for repairs only until about the 2025 timeframe. My interpretation of the 2025 date was that it was based on their parts stockpile. BTW, I observed the Garmin avionics factory at Olathe to be impressive and a first class operation.
 
The 430/530's are terrific units, but I would think twice about spending any money on repairs this late in the game, especially non-WAAS units. If you can swing it, the new line of Garmin navigators are pretty slick.
 
You can always install a pot to supply 0-12 volts to the dimmer input on the 430. The manual dimming can be selected to override the photo cell.
 
I just bought a plane with a 430W, and have the exact same problem you described.

All my searching only finds simple "it's dim" or "it's fried" type comments. You're the only one I found who described something similar to my problem.

Mine is too dim to read the first time I turn it on, no matter how long I wait. If I power it off and back on, it's a little brighter. By the 4th time or so, it's a full brightness the rest of the day.

Did you ever figure out a solution? Before I send it in to Garmin, I'd like to have a good diagnostic, to prevent possibly more than one repair journey.
 
We have had a Garmin 430W in our aircraft for several years and it has become a treasured asset. Recently we began having problems with the display brightness. The problem is intermittent and all of the other functions seem to work fine even though the display does not. I would like to find out if others have seen similar symptoms and if so what the solution might have been.

* Several times, the display went to full brightness and contrast in daytime and became unreadable.
* Once, it went almost completely dark at night and also became unreadable.
* When it fails, the brightness changes gradually, not instantaneously, as if it was adapting to changing light conditions.
* When that happens, the brightness no longer reacts to changing light (e.g. covering the photocell does not reduce the brightness when it is at full bright, and shining a light at it in the dark does not increase the brightness).
* In each case, we were able to recover by switching the lighting from "auto" to manual and reducing/increasing the brightness and contrast values manually to a brightness and contrast close to "9999", their maximum.
* Restarting the unit in the air did not help (after restart, the unit goes back to "auto" lighting).
* However, after the plane has been sitting for a period of time the display operates normally for the next few flights.
* We have checked the avionics buss voltage and it is OK.
* We have checked the cooling air fan and it appears to be OK.

Thoughts, experiences, solutions, recommendations, etc. are welcome.

- larosta

Sounds like the photosensor is failing. I would wire in a manual dimming circuit and re-program the 430 for external dimming. This will bypass the photocell (light sensor) and should solve your problems.

Larry
 
I’m with Larry - I have never had great luck with the “Auto” dimming on our avionics in these bubble-canopy airplanes with lots of light….and then the IFR navigator in our -3 is mounted down between the knees, so it is REALY confused….

I wire up manual dimming and go manual, bypassing the auto setting, in general.

Paul
 
It is quite possible to program the 430w autodimming to work well in night and day.
The settings are essentially y=mx+b linear with a minimum floor dimness for the black of night.
In my case the stock settings were WAY too bright for night flight.
Yes, it is as hard as programming a custom GRT EIS sensor, but no more than that.

Recently my backlight has been acting up but not terrible. Using the manual dimmer input is something this cheapskate will definitely do before giving up. Thanks for the reminder of its existence Larry.
 
Sounds like the photosensor is failing. I would wire in a manual dimming circuit and re-program the 430 for external dimming. This will bypass the photocell (light sensor) and should solve your problems.

Larry

Is this something my local avionics person should easily be able to understand / do?
 
Is this something my local avionics person should easily be able to understand / do?

Yes. The 430 has a Lighting bus HI and LO connection. Just feed 12 volts through a rheostat (wired as a voltage divider) and feed to the HI connection and a ground to the LO. Then go into config mode and change the setting to external/lighting bus from photo sensor. If your shop doesn't know how to do this, it's best to find a different shop.

Larry
 
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