Dimming the Icom A200

[reid]

Greetings.... Despite a search to find the answer I'm seeking, I've
found nothing. I hope some of those who've bolding built and flown
can give me a heads up on what I'm missing.

To be as concise as possible, yet not mislead anyone, here goes as to
my problem.

I'm helping a friend put his Icom A200 into his Europa. All is well,
with the exception of not being able to figure out the dimming and
lighting pin.

The fold out pages that act as a manual say to connect pin B to the
lighting circuit. When the lights are dimmed, the panel light on the
A200 is supposed to go to 1/2 brightness.

If we connect nothing to the pin, there is no back light. It needs
some sort of light during the day to be easily visible. Obviously the
panel lights are not needed during the day, so some power to that pin
is assumed by me to be necessary whenever the radio is on. If we
leave the pin at 14 v. all the time, then it is too bright at night.

I cannot figure out if we've missed something or not. Their
instruction about connecting to the lighting circuit implies that the
pin has no power during daylight operation.

What WOULD make sense is that somehow the radio itself backlights the
display whenever the radio power switch is on. I've checked out
jumpers that are required for power and all, and we have good
connections, and have connected all pins as mentioned in the diagram.

Has anyone installed an A200 and got the backlight to come on during
the day, and also dim at night? If so, can you remember or consult
your diagrams to see how you did it. I seem to be missing something.

And thank you for any help or direction or comments you might be able
to give.

Dale
203EC project

[Scott Skylane]

reid wrote:
> Greetings.... Despite a search to find the answer I'm seeking, I've
> found nothing. I hope some of those who've bolding built and flown
> can give me a heads up on what I'm missing.
/snip/

Dale,

Speaking from experience with a King KY97A, which shares the same
installation wiring diagram, you are not going to be able to do exactly
what you desire re: internal lighting. With pin A disconnected, the
lights will track whatever voltage is present on pin B. If you want it
to light up during the day, you're going to have to turn up the panel
lights.

You've got a couple of options, here. You can install a seperate
"Radio" dimmer, apart from the rest of the panel lights. Or, you can
connect buss power to pin A, which will constantly power the lights at
half brightness. That may be an acceptable compromise. And, I imagine
there exists fancier rheostats, that possess a detent, below the "OFF"
position, which could supply power to a discrete line.

In any case, have fun with the project!

Happy Flying!
Scott Skylane
N92054

[[email protected]]

reid > wrote:
> If we leave [pin B] at 14 v. all the time, then it is too bright at
> night.

If it's got a software setting (something you can adjust by pushing
buttons on the front panel) for LCD contrast, have you twiddled it?
Sometimes LCDs behave oddly when that control is all the way at one
end of its range.

> I cannot figure out if we've missed something or not. Their
> instruction about connecting to the lighting circuit implies that the
> pin has no power during daylight operation.

I have no specific knowledge of this radio, so at first I thought it
might be doing something fancy. But Googling finds a post at

says that the lighting circuit inside the radio is pretty simple.
Basically, there are some lamps inside the radio that have one side
grounded and the other side wired to pin B - you have to provide
some power to pin B to get the backlight to work at all.

Another post in that thread

has a link to a wiring diagram at
http://www.aeroelectric.com/Installation_Data/IC-A200_Icom_Installation_Wiring.pdf
which might be useful.

It doesn't take much voltage drop to substantially reduce the light
output from an incandescent lamp. If you don't have a dimmer control to
connect the radio to, you may need to install one for the radio, or even
a "bright/dim" toggle switch that switches a resistor (voltage drop
whatever you want) or diode (voltage drop 0.5-1.0 V) in and out of the
radio lighting circuit.

Disclaimer: This is based on experience with ground vehicles and
equipment. I don't have an A&P; I don't even have a TG&Y. Your
mileage may vary.

Matt Roberds

[Stealth Pilot[_2_]]

On 22 Apr 2007 09:54:39 -0700, reid > wrote:

>Greetings.... Despite a search to find the answer I'm seeking, I've
>found nothing. I hope some of those who've bolding built and flown
>can give me a heads up on what I'm missing.
>
>To be as concise as possible, yet not mislead anyone, here goes as to
>my problem.
>
>I'm helping a friend put his Icom A200 into his Europa. All is well,
>with the exception of not being able to figure out the dimming and
>lighting pin.
>
>The fold out pages that act as a manual say to connect pin B to the
>lighting circuit. When the lights are dimmed, the panel light on the
>A200 is supposed to go to 1/2 brightness.
>
>If we connect nothing to the pin, there is no back light. It needs
>some sort of light during the day to be easily visible. Obviously the
>panel lights are not needed during the day, so some power to that pin
>is assumed by me to be necessary whenever the radio is on. If we
>leave the pin at 14 v. all the time, then it is too bright at night.
>
>I cannot figure out if we've missed something or not. Their
>instruction about connecting to the lighting circuit implies that the
>pin has no power during daylight operation.
>
>What WOULD make sense is that somehow the radio itself backlights the
>display whenever the radio power switch is on. I've checked out
>jumpers that are required for power and all, and we have good
>connections, and have connected all pins as mentioned in the diagram.
>
>Has anyone installed an A200 and got the backlight to come on during
>the day, and also dim at night? If so, can you remember or consult
>your diagrams to see how you did it. I seem to be missing something.
>
>And thank you for any help or direction or comments you might be able
>to give.
>
>Dale
>203EC project

dale I've used an icom a200 for years and it is unlit during daylight
use.
when you turn on the radio the lcd numerals appear as black on the
background.
I dont think I've ever seen my radio backlit.
it certainly doesnt need backlighting in my aircraft to be visible
....ever when I fly.
I'd agree that there is no lighting power during the day.

Stealth Pilot

[[email protected]]

On Apr 22, 10:54 am, reid > wrote:
> Greetings.... Despite a search to find the answer I'm seeking, I've
> found nothing. I hope some of those who've bolding built and flown
> can give me a heads up on what I'm missing.
>
> To be as concise as possible, yet not mislead anyone, here goes as to
> my problem.
>
> I'm helping a friend put his Icom A200 into his Europa. All is well,
> with the exception of not being able to figure out the dimming and
> lighting pin.
>
> The fold out pages that act as a manual say to connect pin B to the
> lighting circuit. When the lights are dimmed, the panel light on the
> A200 is supposed to go to 1/2 brightness.
>
> If we connect nothing to the pin, there is no back light. It needs
> some sort of light during the day to be easily visible. Obviously the
> panel lights are not needed during the day, so some power to that pin
> is assumed by me to be necessary whenever the radio is on. If we
> leave the pin at 14 v. all the time, then it is too bright at night.
>
> I cannot figure out if we've missed something or not. Their
> instruction about connecting to the lighting circuit implies that the
> pin has no power during daylight operation.
>
> What WOULD make sense is that somehow the radio itself backlights the
> display whenever the radio power switch is on. I've checked out
> jumpers that are required for power and all, and we have good
> connections, and have connected all pins as mentioned in the diagram.
>
> Has anyone installed an A200 and got the backlight to come on during
> the day, and also dim at night? If so, can you remember or consult
> your diagrams to see how you did it. I seem to be missing something.
>
> And thank you for any help or direction or comments you might be able
> to give.
>
> Dale
> 203EC project

I have a A200 in my experimenatl and I totally agree. You can barely
see the digits during the day without the backlight on. At night it is
wayyyy too bright. If I had to do it all over again, during my wiring
process I would have installed a dimmer circuit in the 14v line
leading the the radio light. The instructions that came with the radio
are kinda misleading..

Ben
www.haaspowerair.com