Transistors...

[Guitarmaster]

OK, I have heard that confession is good for the soul, so I have to fess up.

While installing the bezel lighting system, I was tired, managed to wire the system backward and ended up running a dead short across the transistor. This action resulted in a blown fuse and a popped circuit breaker. Subsequently, I wired correctly, replaced the fuse and everything seemed ok.

Upon leaving the instruments lights on for a period of about five minutes, it blew the fuse. After doing some research, I've come to conclusion that the transistor is damaged and needs to be replaced.

It took some doing, but I finally tracked down a reasonably priced 2n2016 transistor.

This is my question; does the transistor just pop out of a socket or does it need to be soldered below the plate where it's mounted? I'm just hoping somebody has some experience doing this so I can go in with a heads up rather than trying to figure it all out on my own.

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[ArtVandelay]

It will need to be soldered, unlike CPU chips, they don't use sockets. You'll need to desolder using suction tube or wick.

[larryb]

In this application, a dimmer circuit, the selection of transistors that will work is large. You do not need an exact part number match. Pretty much any NPN transistor in similar packaging with  >= max collector current and power dissipation will work here. 

Check out this thread:

 

Edited May 8, 2016 by larryb

[larryb]

http://mooneyspace.com/topic/3180-mooney-panel-lights/?page=1

[Hector]

You would want to solder it anyway. With as much vibration these airplanes see anything in a socket could be problematic.

[Guitarmaster]

Thanks for the replies! That's kind of what I thought. Now it's just a case of getting that panel out.

What is the easiest way to get that panel out?

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[Marauder]

Thanks for the replies! That's kind of what I thought. Now it's just a case of getting that panel out.

What is the easiest way to get that panel out?

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SawsAll Sparky! You didn't say anything about getting it back in.

[Piloto]

I had the same problem and end up bypassing the transistor and just having switch to full brightness or off. Highly reliable now, no chance of transistor or pot failure. Loosing the instruments lights at night is worse than loosing the vacuum pump since you can't see the ASI, TC, VSI, compass or the altimeter. The original instruments variable red light purpose was to allow the pilot to better spot the lighthouses and airport rotating beacons at night. One problem I had was differentiating police cars dome lights from airports. Before the days of radio navigation lighthouses were key to successful flight at night.

José

Edited May 8, 2016 by Piloto

[Yetti]

These are the big transistors on top of the wheel well?   Least that makes the most sense.   Not sure how you get to them out or back in without pulling the whole panel.   For a little work with amazon you could be in business with a PWM dimmer

http://www.amazon.com/Dimming-Controller-Adjustable-Brightness-Zitrades/dp/B007V1B0W8

[Yetti]

PWM module is how the newer mooneys do it.

[Guitarmaster]

On May 8, 2016 at 5:03 PM, Yetti said:

PWM module is how the newer mooneys do it.

I have considered this and it is an attractive option.  

Right now I have the transistors on the way so I am going to keep it stock for now was I am sure there more than a few hoops to jump through to change it to a PWM.  Of course, if the hanger fairies were to do it without my knowledge.....

[N201MKTurbo]

I wouldn't unsolder the wires unless they are very short. just cut them off the E and B terminals as close as you can, re-strip the wires and put them back on. Make sure to put heat shrink on the wires after soldering, it will stabilize the wire so they won't fracture from vibration.

[Yetti]

10 hours ago, Guitarmaster said:

I have considered this and it is an attractive option.  

Right now I have the transistors on the way so I am going to keep it stock for now was I am sure there more than a few hoops to jump through to change it to a PWM.  Of course, if the hanger fairies were to do it without my knowledge.....

IF these are the transistors down on the top of the wheel well, I have no earthly idea how you will get to them.  All the panels on either side are riveted.  Even if you remove the inst Panel, not sure if you can get to them because of the throttle cables and steel bars.

The PWM would just replace the rheostats with knobs up on the panel.   Let us know how hanger fairies fare..