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Any LC-40 Failures?

Ironflight

Ironflight

VAF Moderator / Line Boy
Mentor
...Other than mine?

Just wondering if anyone has had any problems with the LC-40 lighting controller board. Mine is one of the older ones, no case - just a bare board that I mounted behind the panel. Today, while cruising out to the San Antonio area, I noticed that I had a popped circuit breaker - my internal lighting. That supplies power to the LC-40,and all the panel lights are powered off of that (except my flexible map lights, and of course, my EFIS and other internally lighted avionics). I don't believe in resetting non-essential breakers in the air, so when I landed, I looked at the Amp reading on my EFIS as I pushed in the breaker - amps climbed to 5 above steady state and the breaker blew. I'm convinced - got a problem!

I'm really not in a hurry to tear into the wiring, as all the internally lit stuff is more than I need if I were flying really late, but before I tear into it, I'm wondering if anyone else has experienced this board failing ?

Paul
 
Ironflight said:
...Other than mine?

Just wondering if anyone has had any problems with the LC-40 lighting controller board. Mine is one of the older ones, no case - just a bare board that I mounted behind the panel. Today, while cruising out to the San Antonio area, I noticed that I had a popped circuit breaker
Click to expand...

Hi Paul,

You might try checking the back of the board - perhaps a sliver of 2024 or somesuch has landed between two traces. What regulator is on the board? I'm guessing a LM317.
 
I had some problems with my B&C dimmer..

I don't recall the model off hand but mine has the heat sink on it and I recieved 2 bad ones new from BC, finally just repaired the second one myself. I forget exactly what it was but it was either the insulating washers or solder flash on the board that had the case of the large TO3 transitor shorted to ground. The case is the output so if it shorts to ground the current will trip the fuse or breaker. Hook an ohm meter between the case of the transisitor and ground to see what you get, if it's zero then look for the short. Of course if you have an older unit an it has been working fine for years then it's likely the output transistor is shorted (common failure if it's been running for a long time).
 
Thanks for the feedback guys. I checked over my notes and unless I have a wire short somewhere, the problem almost has to be in the dimmer board. In actuality, it does have a lot fo runtime, becasue the airplane was alive through ground power supplies in the shop for many, many hours before it was finished - and the dimmer circuit was powered all tha time. I'm building a little fault tree of things to check when I get a cool day and want to pull the panel, and I bet it will be the output transistor....

Paul
 
Paul..

If your does not have the hint sink then you need to install one, even thought the TO3 case of the output seems large it cannot disipate heat very well without a heatsink.
Walt
 
I've had 2 failures of these units now, and I have not reinstalled a 3rd one. I rewired with heavier duty dimmer circuits, even though the circuit totals were well below rated capacity. They do not impress me as being very reliable.

Vic
 
vic syracuse said:
I've had 2 failures of these units now, and I have not reinstalled a 3rd one. I rewired with heavier duty dimmer circuits, even though the circuit totals were well below rated capacity. They do not impress me as being very reliable.
Click to expand...

Wow - I don't know what they used on this LC-40, but I wired my own by using a linear voltage regulator. I was only powering a few lights so I needed less than 1.5 amps of variable brightness.

It is super easy:


  • Download this datasheet. See page 7 of the datasheet for a sample schematic
  • Install the LM317 (available from Digikey, Fry's, possibly even radio shack)
  • Install R1, R2 and C1 - a total of only four components, you don't even need a circuit board. The value of C1 is not critical, it's just for noise suppression.

Should cost less than $5 and take less than an hour to build.

Update: Just checked the web, radio shack has 'em
 
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You're right, and I had done this on my previous 5 airplanes. I thought I would be quicker and use the LC-40 on this one, and I have regretted it ever since. :(
Vic
 
Davepar said:
Can those be used on LED lights as well?
Click to expand...

yes - if they are already mean't to hook to 12V. In that case the LED has a resistor in series so that you can change the brightness with this LM317 as you wish.

If you want to use a 'raw' LED with this regulator (or any voltage source really), you'll need to ensure that the LED is connected to the supply through a resistor. (A cheezy way of varying the current through the LED based on voltage)

You can use the information on your particular LED with a calculator like the following to pick out the appropriate resistor: http://ourworld.compuserve.com/homepages/Bill_Bowden/led.htm .
 
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Thanks. Yup, my LED lights are in series with a resistor. Now to see if I can return that LC40. I just ordered it a few weeks ago before I knew it was so troublesome.

Dave
 
Update

Well, I pulled the panel Saturday afternoon and did some troubleshooting to try and find my short - sure enough, it is in the LC-40. I didn't pin it down further than that, as I don't have a spare to drop in, and didn't want to leave all the wires dangling while I order one. (Instead, I took the power input wire and temporarily connected it directly to my panel E/L flood strip - gives me more than enough light!)

It would be a bit of a pain to re-wire for a home-brewed dimmer system now (wish I'd gone that way in the first place), so I will probably go back with an LC-40 (at least one more time) - Has anyone used the new version of the LC-40, the one in the case? Just wondering if it does any better than the old style. I never really liked the plain, unprotected board mounted behind the panel.

Paul
 
making your own dimmer

Kevin,

I think I will take a shot at making my own dimmer given the instructions that you posted. I went to radio shack today with the instructions I downloaded. I was hoping the radio shack guy could help me understand how to make it fromt he schematic. No joy.

Do you have a pic of what it should look like when assembled? Do you mount it in a project box?

Thanks,

Tony
 
LC-40 = PWM Dimmer?

Hey Paul,

I looked at Van's accy catalog and it looks like the LC-40 is a 4 channel low freq PWM unit??? If so, its not going to be a heatsink issue. Linear regs will shut down on overheat but not short out. A PWM unit may not be as tolerant.

Yours may just be broken (those 200+ plus wonderful hours can take a toll, you know). Be sure before you install the new one that you run the wires and look for a fray/short downstream that would fry the output stage of your new one.

I know you have a Shuttle to launch (yeah, yeah, excuses, excuses) but before you roll your own, maybe I can help you get yours back up. Send me an email, I'm near Dallas. Short finding...I can do... having created many myself..

John

PS: I too have designed a LoFreq PWM dimmer for my plane. Drives anything from LEDs to halogens, push and/or pull. Intrinsicaly protected against shorts, reverse polarity and OV transients. Fits on same holes as the 'popular' one. Showed it to my 'buddies' at the hangar and they scoffed in favor of those pathetic '317 dimmers.

Fools! I shall crush them all!
 
lucky333 said:
I know you have a Shuttle to launch (yeah, yeah, excuses, excuses) but before you roll your own, maybe I can help you get yours back up. Send me an email, I'm near Dallas. Short finding...I can do... having created many myself..

John
Click to expand...

Thanks John ! I think mine might have succumbed to vibration and possibly some interference with a fresh air duct (there was some evidence of it rubbing on the components. I'm in no hurry now, as I have plenty of lighting for my needs - the only things not working right now are my two eyeball floods and the internal dimming on the #2 Comm (ICOMM A-200). I might let it go until condition inspection in a couple months - or until I get done with the next mission!

One other thing I should mention is alternate lighting. I have my flexible map lights (blue LED's on flex stalks, ex-laptop computer USB reading lamps) mounted under my canopy rail - either one of which, when pointed forward, gives plenty of suffused light to make the panel readable. In addition, I have a "mic light" on my microphone boom - it has selectable red/white LED's, and puts a spot exactly where you are looking. With all that redundancy, I have now figured out I have at least one too many methods of cockpit lighting....

If someone were looking to go simple? I'd go with a mic light and forget the rest...

Paul
 
mic light?

OK Paul, now that you have tantalized us with the mic light information you have to come forward with the details. I had never thought of such a thing, but it is a great idea.

How is it powered, how is red/white selected, did you make it, do you have pictures of it? Inquiring minds etc.

Tony
 
Seitz Mike Light

SOrry about that guys....no time to post a picture this morning, but here is a link to the guys who make it - great prodcut - lots of users in the military:

http://www.seitzinc.com/shop/page1.html

It is powered by a little battery pack (I forget if it is AA's or 9v - but small, and replaceable), and has a switch you can touch with your tongue for on/off, and a toggle switch on the battery pack for red/white. I have mine on the boom mic for my helmet, and the battery pack is just velcroed on the back, by the nape of my neck - works great!

Paul
 
FYI

I found this kit on Ebay that contains five LM317T Voltage Regulators and other parts to make a few dimmers for $11.00.


ebay_kit.gif
 
I bought it.

JonathanCook said:
I found this kit on Ebay that contains five LM317T Voltage Regulators and other parts to make a few dimmers for $11.00.
Click to expand...
I bought it and have not soldered it up yet. You only get one board but its a do it yourself deal, but for the money you get lots of little parts and a 5 regulators for a little more than just one regulator at Radio Shack.
 
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