This is a visual inspection to see what I'm up against. So without delay lets get into it.

Disassembly: First remove the foil around the rear of the bezel. Unthread the large black ring on the back of the connector. There is a large O-ring that will come out after the back has been removed. The RMI internally is divided into six sections.  I have described them from Front Face to the Rear Connector.  This is just to inspect the unit and see what I will have to plan for, as of yet I still have not found/received any documentation, so in a way, I'm just sort of spitting in the wind. You will please notice that I have removed the supports from the connector assembly so it just sort of hangs there. At this time I am not willing to dive deeper into the RMI, for fear of producing damage. As you will see in image number 4. The green wire has broken loose of the black motor.  I guess I will have to repair it.

ItemSectionsSubsectionsManufactureManufacture Part NumberCollins Part NumberNSN
1.Front Face
aThe following Drivers are involved with Compass Card Movement
b3b, 3c, 5a, 5b, 5c
cFront Pointer
dRear Pointer
eADF/VOR Switch Right
fADF/VOR Switch Left
g+/- Adjustment
2.Rear Pointer Drive & Flag Motors
aSynchro RxLitton/CliftonURH-11-CM-4/F470602894-25990-00-253-0261
bIndicator MotorJewel241004-103
cFlag MotorJewel
3Drives & Switches
aControl Transformer (has external slip rings)Litton/CliftonCTH-10-ES-05/A216739681-1
cTransformer (Front Pointer Drive)Litton/CliftonCRH-10-PS-4/B2117398305990-00-951-8283
dTachometer, ST10131Cedar Engineering
eSwitch (S301 - Left)ClarostatCM3178317550985930-00-127-5586
fSwitch (S301 - Right)ClarostatCM3178317550985930-00-127-5586
5.Rear Drives
.aSynchro Tx #3406 (large Gold Cans)Sunbeam Electric4022-025990-00-504-6032
.bSynchro Tx #9980 (large Gold Cans)Sunbeam Electric4022-025990-00-504-6032
6.Connector System
.aConnector 55 pin connector numbered 1-55
.bFlex circuit PCB holding two (2) green termination plates for wires
.cGreen Termination Board 10x2Winchester ElectronicsMBD10-2-535940-00-006-2944
.dGreen Termination Board 10x5Winchester ElectronicsMBD10-5-535940-00-617-1341
  1. Numbers in BOLDare printed on the part
  2. Numbers not in bold have been cross-referenced and looked up.
  3. Litton/Clifton is now part of MOOG
  4. Sunbeam Electric is now part of MOOG

And Now the photos


The Rear Pointer Drive Synchro
image 1
One of the ADF/VOR switches
image 2
image 3image 4
image 5Tachometer and Front Drive Synchro
image 6
Close up of the front pointer drive shaft.
image 7
The business end of the RMI
image 8
image 9



  • Attack of the Blond Moment on the RMI it says "Honeywell" ie Sperry 25 Sept 2018