Instrument Panel Lighting

[n9002a]

We still have 6 fuses on our 1949 170A (N9002A). I found a blown 10A fuse in the 4th fuse holder from the left and replaced it. I still do not have any lights on the panel. I checked the panel lighting switch and it has continuity, which is about all I know about elictricity. Any ideas?

[Bruce Fenstermacher]

Yes I have some ideas. But if your knowledge of electricity is limited the best idea I have is to find someone with more knowledge than you have to help you. This is a relatively simple circuit but you do have to know what your looking at, and what to look for, or you will never get it fixed.

Here is what I would do. First I have to assume you have stock lights which clip into the panel from the back. Most likely the ground for each light is bad. They rely on the clip itself to make contact with the panel and that the panel is grounded. So start with the panel. Is it grounded? Check for continuity from it to a good ground. If it is not grounded add a ground. Then move to each of the lights and check them for a good ground. If you are lucky you can unclip them and clean then and the panel where the clips touch. If you can not get good grounds this way a ground wire can be run from an good ground directly to the outside of each light socket. Of course you will have to attach the ground to the socket and there isn't going to be a method to do so. But one way is to solder the wire directly to the outside of the socket.
Once you know you have good grounds to each socket then make sure power is getting to the center contact of each socket from the rheostat. Good ground and good power should mean a working light. Of course I'm assuming the bulbs are good which in retrospect should be the first thing to check.

[n9002a]

Found the problem, but not the solution, yet. It seems that the blown fuse was an AGS10 (9/32 inch diameter) and the new one I installed was an AGC10 (1/4 inch diameter). The 120/140 Forum shows that MDM-10 is the same as AGS10, so I'm looking. The auto stores (6 so far) don't carry them.

[bagarre]

Wrap the ends with some tin-foil?

[Bruce Fenstermacher]

Good luck and let us know if you find any. You can find them listed at places like Mouser Electronics but you will have to order them.

I've heard but have not confirmed that if you are careful you can break the end caps of the blown AGS and insert them on the AGC fuse. Maybe not as messy as wrapping the ends with foil and not ideal but might get you by till you find some.

[GAHorn]

Gulf Coast Avionics sells a replacement fuse holder for the AGC fuses.

[Bruce Fenstermacher]

Gulf Coast Avionics sells a replacement fuse holder for the AGC fuses.

As do others like Spruce for $1.87. The trouble is George have you looked at a the original fuse holder/wire harness nightmare under the piano switches of a '52 or earlier? If you have you wouldn't quickly suggest the holder be replaced. It is a major undertaking. And if someone was going to do it I'd suggest going with breakers though that solution will run nearly $200 as I recall just for the breakers.

Another thing is the breakers and I believe the AGC fuse holders are smaller that the original holes. I addressed this when I converted to breakers by making duplicate plates of thin aluminum the same size as the original but with smaller holes centered on the old then sandwiched the old fuse area front and back with the plates. The breakers (or fuse holders) will hold it all together nicely.

Easer to find (order) a few AGS fuses though.

[GAHorn]

Yeah, I know. I just figured that if some one needed to replace only one.....that might be a simple solution, with a flat washer.
Theres a reason I have circuit breakers.

[eloughlin]

I have located a source of 4AG/AGS fuses, even the notoriously hard to find/expensive from Cessna 15A slo-blo for the flaps. Let me know what you need and I will see what I have.

I came over here from the 150-152 Club since I thought there might be the same need for these new-old-stock fuses!!

E-mail: e4loughlin@numail.org

Hope this helps a few on here like it has over on the other website!

Edward

[blueldr]

Instrument lighting?

Real pilots hold a flashlight in their mouth!

[n9002a]

Does anyone have the recommended capacities for the fuses from left to right?

[n2582d]

Fuse Picture.jpg

Fuse List.jpg

[n9002a]

Great service.
Thanks

[Bruce Fenstermacher]

FuseDecals48.jpg

This is a picture of the original decals found on 48 and 49 170s.

So not taking into account any modifications since the factory the values of fuses left to right are: 15, 15, 10, 10, 25, 25.