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Weird power . . .

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teamgrumman(at)yahoo.com
Guest

Posted: Sat Nov 16, 2013 8:35 pm Post subject: Weird power . . .

I'm troubleshooting Cabin and Map lights not working.  

First thing I notice is the fuse is blown.  Replaced the fuse.  Nothing.

Next, the lights are burned out.  Replaced the lights.  Nothing.  

I remove the plastic cover on the switch.  The power wire, 51LA3, is connected to the map side of the switch, not the middle.

   -- fixed that.  Nothing.

Checked for power at 51LA3 with the switch off.  12.5 volts.

Turned on Map, then Cabin light.  Nothing.  

Measured power on 51LA3 with switch on Map.  0 volts.  

Checked the fuse.  Blown.  Replaced.  Still nothing.  

I disconnect all of the wires.  I have power on 51LA3.  

  -  I connect it directly to the cabin light wire, no. 5LA5.  Nothing.

  -  I connect it to the map light, no. 5LA4.  Nothing.

I remove the wire to the side light, powered by the rheostat, wire no. 51LB6.

I connect 51LB6 to 5LA4.  Map Light works.

I connect 51LB6 to 5LA5.  Cabin Light works.

I connect to the middle terminals on the Cabin/Map switch.  Lights work.

I measure power on 51LA3.  12.5 volts.  

I connect 51LA3 to the side light.   Nothing.

Double check power on 51LA3.  12.5 volts.

I leave the VOM on the 51LA3 measuring 12.5 volts.  While connected, I attach the side light.  Voltage gradually drops to 0 volts.

  - light never comes on.  Double check with Map and Cabin lights.  Same.

----->>>>>  With the voltage on 51LA3 measuring 12.5 volts, any attempt to load the circuit with a light drops the voltage to 0 volts.

Fuse is good.  Power is there.  Doesn't work when light  attached.

This is a new one to me.  

PS, I checked the connection on the battery box fuse holder.  It looks OK.  Clock works  fine.



 [quote][b]

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flying-nut(at)cfl.rr.com
Guest

Posted: Sat Nov 16, 2013 9:00 pm Post subject: Weird power . . .

Not having a diagram to follow the       steps below .... here's a WAG.

       I suspect that you're missing a ground and the voltage you're       measuring is being back-fed somewhere.  Check the side light       ground.

       Linn

       

       

       On 11/16/2013 11:29 PM, Gary L Vogt wrote:

     

     [quote]                I'm troubleshooting Cabin and Map lights not working.  

         

         

         First thing I notice is the fuse is           blown.  Replaced the fuse.  Nothing.

         Next, the lights are burned out.            Replaced the lights.  Nothing.  

         I remove the plastic cover on the switch.            The power wire, 51LA3, is connected to the map side of the           switch, not the middle.

            -- fixed that.  Nothing.

         Checked for power at 51LA3 with the           switch off.  12.5 volts.

         Turned on Map, then Cabin light.            Nothing.  

         Measured power on 51LA3 with switch on           Map.  0 volts.  

         Checked the fuse.  Blown.  Replaced.            Still nothing.  

         I disconnect all of the wires.  I have           power on 51LA3.  

           -  I connect it directly to the cabin           light wire, no. 5LA5.  Nothing.

           -  I connect it to the map light, no.           5LA4.  Nothing.

         I remove the wire to the side light,           powered by the rheostat, wire no. 51LB6.

         I connect 51LB6 to 5LA4.  Map Light           works.

         I connect 51LB6 to 5LA5.  Cabin Light           works.

         I connect to the middle terminals on the           Cabin/Map switch.  Lights work.

         I measure power on 51LA3.  12.5 volts.  

         I connect 51LA3 to the side light.            Nothing.

         Double check power on 51LA3.  12.5 volts.

         I leave the VOM on the 51LA3 measuring           12.5 volts.  While connected, I attach the side light.            Voltage gradually drops to 0 volts.

           - light never comes on.  Double check           with Map and Cabin lights.  Same.

         

         

         ----->>>>>  With the           voltage on 51LA3 measuring 12.5 volts, any attempt to load the           circuit with a light drops the voltage to 0 volts.

         

         

         Fuse is good.  Power is there.  Doesn't           work when light attached.

         

         

         This is a new one to me.  

         

         

         PS, I checked the connection on the           battery box fuse holder.  It looks OK.  Clock works fine.

       

        	  Quote: 	
		  



	
       

No virus         found in this message.

         Checked by AVG - www.avg.com

         11/16/13     [b]

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grumpyparts

Joined: 28 Jan 2009
Posts: 65
Location: EGHH

Posted: Sun Nov 17, 2013 12:42 am Post subject: Weird power . . .

Sounds like an hr joint in the LA5 supply. Check condition of the JP-6-3 plug near the battery box. Also there seems to be a joint where the LA5 wire charges to an LA2, not sure where that is.

Ian



Sent from my iPhone



On 17 Nov 2013, at 04:29, Gary L Vogt <teamgrumman(at)yahoo.com (teamgrumman(at)yahoo.com)> wrote:

[quote]I'm troubleshooting Cabin and Map lights not working.  

First thing I notice is the fuse is blown.  Replaced the fuse.  Nothing.

Next, the lights are burned out.  Replaced the lights.  Nothing.  

I remove the plastic cover on the switch.  The power wire, 51LA3, is connected to the map side of the switch, not the middle.

   -- fixed that.  Nothing.

Checked for power at 51LA3 with the switch off.  12.5 volts.

Turned on Map, then Cabin light.  Nothing.  

Measured power on 51LA3 with switch on Map.  0 volts.  

Checked the fuse.  Blown.  Replaced.  Still nothing.  

I disconnect all of the wires.  I have power on 51LA3.  

  -  I connect it directly to the cabin light wire, no. 5LA5.  Nothing.

  -  I connect it to the map light, no. 5LA4.  Nothing.

I remove the wire to the side light, powered by the rheostat, wire no. 51LB6.

I connect 51LB6 to 5LA4.  Map Light works.

I connect 51LB6 to 5LA5.  Cabin Light works.

I connect to the middle terminals on the Cabin/Map switch.  Lights work.

I measure power on 51LA3.  12.5 volts.  

I connect 51LA3 to the side light.   Nothing.

Double check power on 51LA3.  12.5 volts.

I leave the VOM on the 51LA3 measuring 12.5 volts.  While connected, I attach the side light.  Voltage gradually drops to 0 volts.

  - light never comes on.  Double check with Map and Cabin lights.  Same.

----->>>>>  With the voltage on 51LA3 measuring 12.5 volts, any attempt to load the circuit with a light drops the voltage to 0 volts.

Fuse is good.  Power is there.  Doesn't work when light  attached.

This is a new one to me.  

PS, I checked the connection on the battery box fuse holder.  It looks OK.  Clock works  fine.



  	  Quote: 	
		  



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[b]

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n76lima(at)mindspring.com
Guest

Posted: Sun Nov 17, 2013 5:25 am Post subject: Weird power . . .

The most interesting comment, and the one I'd follow up on, is that the "voltage gradually drops to zero." 


Try loading the circuit with a high wattage light bulb, rather than the VOM that has very high impedance.


It will show up resistance issues that a VOM will not, when set to volts, and not resistance.


--Bob Steward

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