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overhead switch panel cover


Guest Mike261

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Guest Mike261

I can't see the labels on the overhead switches at night...mechanic pulled the cover today looking for a lamp to replace but no lamp. its a weird looking setup. anyone dealt with this before? it's also labelled 115v 400 hz which is odd.IMG_3273.JPG

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Guest Mike261

I understand the reasoning behind 400 hertz lighting for aircraft...smaller windings on transformers makes for lighter, but I was surprised to see it here. I have yet to come across something labelled 400 hertz on my mooney, everything Ive seen is 28 volts...but i havent seen everything.

anyway, the panel cover appears to have a lamp built into it, and probably requires a completely new plate.

in my line of work a switch plate costs less than a buck, I cant wait to see what this will cost...

mike

 

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The 115V part is the most surprising.

Some of the gear indicators I referred to were 28v in a 14v plane... a factor of two.  115v bulb in a 28v plane has got to be pretty dim. A factor of almost four.

PP thoughts, not an electrical engineer...

Best regards,

-a-

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  • 2 years later...

 

On 10/20/2016 at 8:28 PM, Guest Mike261 said:

I can't see the labels on the overhead switches at night...mechanic pulled the cover today looking for a lamp to replace but no lamp. its a weird looking setup. anyone dealt with this before? it's also labelled 115v 400 hz which is odd.IMG_3273.JPG

IMG_3272.JPG

Hoping you are still online but unsure based on your avatar.

Did you (or anyone) ever figure out how to change the light inside the Exterior Lights Overhead Switch?

I looked up the part-number on Lasar to my dismay: https://lasar.com/switches/overhead-switch-panel-150085-005?rq=150085

$404.29 (ouch)

Hoping there is a bulb in there to change that cost significantly less.  Going to check power to the input wire first.

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11 hours ago, Bryan said:

I looked up the part-number on Lasar to my dismay: https://lasar.com/switches/overhead-switch-panel-150085-005?rq=150085

$404.29 (ouch)

Hoping there is a bulb in there to change that cost significantly less.  Going to check power to the input wire first.

There is no bulb to change. The panel is an Electroluminescence panel which requires AC power. There is also a small invertor (28 VDC -> 115VAC) in the overhead to power the panel. If it burns out your only choice is to replace the entire panel.

I have replaced the panel once on my 1996 M20J. I replaced the invertor at the same time. That was about 6 years ago so about a 15 year lifetime. The insulation on mine starting wearing off and shorting to the airframe (not a good thing). The panel had started to dim so I decided it was time to replace.

Jim

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1 hour ago, jcovington said:

There is no bulb to change. The panel is an Electroluminescence panel which requires AC power. There is also a small invertor (28 VDC -> 115VAC) in the overhead to power the panel. If it burns out your only choice is to replace the entire panel.

I have replaced the panel once on my 1996 M20J. I replaced the invertor at the same time. That was about 6 years ago so about a 15 year lifetime. The insulation on mine starting wearing off and shorting to the airframe (not a good thing). The panel had started to dim so I decided it was time to replace.

Jim

Thanks for your response.

Is the inverter located in the avionics bay?  Is it a box or something in the overhead switch panel.  (Looking for a part number in my IPC)

I need to figure out if it is the Elctroluminescence panel or the inverter.

 

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56 minutes ago, Bryan said:

Is the inverter located in the avionics bay?  Is it a box or something in the overhead switch panel.  (Looking for a part number in my IPC)

I need to figure out if it is the Elctroluminescence panel or the inverter.

The inverter is located in the overhead headliner very close to the EL panel (2 to 3 inches away). As I recall I had to drop the headliner to access the inverter. From my notes (2008, my how time flies) the inverter is LP105A in the parts manual and is an ERG LPS28-3-3P. I have attached the specs below. It is probably a commercially available part but I just ordered both parts from Dan at LASAR for convenience. I believe the inverter was about $100.00.

It is fairly easy to check the inverter. From the spec sheet for the part number an LPS28-3-3P will take in 28VDC and output 120 Vms. A DMM on the AC scale will show if you have voltage on the pins on the connector. If you have voltage but no light the inverter is good and the panel is bad. Something less than 120 AC will cause the panel to be dim.

In my searching for a replacement panel there are places that repair EL panels. I kept my old panel and may try the repair route next time.

Jim

lps.pdf

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