Panel lights rheostat M20C 1965 / Updated 9/2018

[Drumstick]

So it seems like every time I fly something else breaks.   Today it was my panel lighting.   The dimmer switch functions as an on/off and dimmer rheostat.  They were fine a couple weeks ago but tonight the switch just turns the lights on and off but no dimming.

Pretty sure the switch isn't original as the panel was modded years ago with post lights.  Any idea of a particular part number, replacement switch or a way to troubleshoot the current rheostat?

Edited September 26, 2018 by Drumstick

[neilpilot]

51 minutes ago, Freemasm said:

I'll get you a part number later if you don't get it beforehand. Won't be home for a few hours. 

How do you get someone else a part # if his switch isn't original, due to modification?

[Drumstick]

1 hour ago, neilpilot said:

How do you get someone else a part # if his switch isn't original, due to modification?

It might be original!  (Unlikely).  It has several leads off the back that have been soldered to the switch.  One of the leads has a pigtail that has been wired to another post on the rheostat.

Edited August 20, 2017 by Drumstick

[neilpilot]

2 minutes ago, Drumstick said:

It might be original!  

OK, since you've moved from "Pretty sure the switch isn't original" when you started the thread to "It might be original! ", who am I to say.  I have a new replacement for the "original" 65C rheostat in my hangar.

[Drumstick]

3 minutes ago, neilpilot said:

OK, since you've moved from "Pretty sure the switch isn't original" when you started the thread to "It might be original! ", who am I to say.  I have a new replacement for the "original" 65C rheostat in my hangar.

I don't know what is or isn't original - the panel was redone in the early 90s.  Is the current dimmer the original and just moved?  What I do know is that I have the original parts manual and diagram and I can't make sense of what mine is relative to the panel.   I'll try to get pics of the back of mine later.

Edited August 20, 2017 by Drumstick

[Drumstick]

4 hours ago, Freemasm said:

The original component was a ceramic wire wound Rheostat switch. There were a lot of changes and "or equivalent" back in those days. Chances are, the original Rheo/switch was an Allen Bradley JS1N04P251MA from the Mooney drawing I had. These are used to bias solid state power transistors for light level control. Assuming that part (transistors) of the circuitry is still installed, you could:

Check with Ohmite whom (I believe) still makes Rheo/switches.

Look for a surplus equivalent (expensive) or a potentiometer to replace. Not everything labeled a Pot truly is. Can cause issues.

Or you could replace the dimming circuit with something from the MaxDim folks. This would replace the dimmer/switch and power supply but it will work long after we're gone.

I have a 69C, I know the frustration. Check your 337s and take a look at the circuitry. Take/post some pix. Best of luck. Will help where I can

 

This was helpful.  I'll try to squeeze under my panel tonight and take some pictures.  I have every scrap of paper on this airplane back to 1965 including an original sales brochure.

[Guest]

Does this help?  Item 35 is the rheostat.

Clarence

[carusoam]

Doesn't get any better than that, way to go Clarence!

Best regards,

-a-

[Drumstick]

Resurrecting this thread because it has become relevant again.  Last year I started this thread because my dimmer switch wasn't working and when I went back to the hangar to take pictures etc it miraculously was working.  Well...fast forward to now and its NOT working...so I will go back to the hangar and get pics this time...hopefully taking pictures of the switch will make it work...if it doesn't I will post some pictures and let everyone know.

 

Edited to add:

Type JS

 

Edited September 26, 2018 by Drumstick
added pics

[Yetti]

Might seem like overkill, but a PWM module could be your new friend.   PWM can work with LEDs

 

[0TreeLemur]

Certified PWM is not for CB's.

[steingar]

Panel lighting?

All I got is the original red light from the ceiling, which illuminates less than most Philosophy textbooks.  Makes night flying interesting.

[Yetti]

3 hours ago, Fred_2O said:

Certified PWM is not for CB's.

It is only me that noticed that the Amazon version of the spruce PWM is the same?  Oh this is an upgraded one with a on off switch.   Just upgrade the switches to the protective cover ones.

https://www.amazon.com/NOYITO-Controller-10V-50V-Forward-Reverse/dp/B07CBSCMZY/ref=asc_df_B07CBSCMZY/?tag=hyprod-20&linkCode=df0&hvadid=241912880102&hvpos=1o3&hvnetw=g&hvrand=17344091327607277272&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9027599&hvtargid=pla-446011613970&psc=1

 

[0TreeLemur]

 

13 hours ago, Yetti said:

It is only me that noticed that the Amazon version of the spruce PWM is the same?  Oh this is an upgraded one with a on off switch.   Just upgrade the switches to the protective cover ones.

https://www.amazon.com/NOYITO-Controller-10V-50V-Forward-Reverse/dp/B07CBSCMZY/ref=asc_df_B07CBSCMZY/?tag=hyprod-20&linkCode=df0&hvadid=241912880102&hvpos=1o3&hvnetw=g&hvrand=17344091327607277272&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9027599&hvtargid=pla-446011613970&psc=1

 

That one on Spruce https://www.aircraftspruce.com/catalog/elpages/singlechannelpwm.php that looks like the one on Amazon is not certified.   The certified one definitely has a price that would repel a CB.   The certified one on spruce here: https://www.aircraftspruce.com/catalog/elpages/maxDimUnit.php