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====== A-4 Rear Seat Trim Indicators ======

===== Complaint =====

The rudder and elevator trim indicators were not working.

===== Problem =====

When examining the rudder and elevator trim indicators, they were labeled INOP. Taking the assembly out of the console showed that they were disconnected. The cable to be connected to them was inside of the right leg console area. Reconnecting the cable showed that:

  - The meter indications were flickering
  - The front seat indicators were thrown off by connecting the rear seat assembly to the cable

An examination of the schematic for the indicators, which are three-coil meters, show that the front and back assemblies were connected together in parallel, and then connected to the position transmitters from the tail. 

The indication from the front - 7 degrees for the horizontal stab (elevator) and 0 degrees for the rudder, was correct. When connecting the rear seat meters, the new indications were incorrect (11 degrees for the horizontal stab and 2 degrees right for the rudder).

As a test, we disconnected the front seat's meters and connected them to the rear seat wire, and the indications were accurate, so the wiring is deemed correct.

{{:projects:a4work:20190103_125037_r.jpg|}}

{{:projects:a4work:20190103_125044_r.jpg|}}
===== Result =====

We decided to return the configuration back to its original state. The rear seat cable is back inside the console area, but disconnected. 

New meters will be ordered.

**Internal light bulbs**

It is likely that the internal light bulbs are working. I measured 70 ohms between pins 1 and 4 for the rudder meter, and 80 ohms for the elevator meter. There is another complaint that the rear seat console lighting is not working, so this may be the cause that lighting is not working in these meters.

{{:projects:a4work:meterpinnumbering.jpg|Dan's numbering}}

Measuring between 3 to 5, 3 to 6 and 5 to 6 all were about 430 ohms. Pin 2 is open. I think Pin 1 gets grounded. Pin 4 is to light the gauge.

1/3/2019
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