TM 11-5840-360-14-1-1
ATTACHMENT A
NSK CONVERSION INSTRUCTIONS
The following procedure should be used to convert the North Stabilization Kit installed in any 12 inch or 16 inch indicator
for operation with any one of four different input voltages. The conversion requires replacement of components on the
NSK Assembly (A9) proper and on both of the attached PCB assemblies, A9A1 and A9A2.
BEFORE STARTING MODIFICATION
1. Referring to Table A-2, determine the value and part number of the components required for NSK operation at the
desired input voltage.
2.
Obtain the required number of components (for the total number of indicators to be modified) through normal
channels.
NSK ASSEMBLY MODIFICATION
1. Referring to the maintenance section of the basic radar manual, gain access to the NSK Assembly in the Indicator.
2. Remove the Resolver Drive (A9A1) and Exciter (A9A2) PCB assemblies from the NSK (A9) Assembly. Refer to the
assembly drawing in the basic radar manual for location.
3. Locate the three 25 watt resistors, R1, R2, and R3 on the NSK Assembly.
4. Replace these resistors with 25 watt resistors of the proper value for the desired input voltage. See Table A-2.
5. Locate and replace R4 (2 or 3 watt resistor) with a resistor of the proper value and wattage as determined from Table
6. Using Table A-3, program the NSK Assembly for negative 28 volt steps.
RESOLVER DRIVE ASSEMBLY (A9A1) MODIFICATION
1. If necessary, replace the plug-in relay K1 with a relay of the correct voltage and coil resistance as specified in Table
NSK EXCITER ASSEMBLY (A9A2) MODIFICATION
1. Locate and replace the t watt resistors R1, R2, and R3 with watt resistors of the correct value for the desired input
voltage per Table A-2. See the basic radar manual drawings for location.
2. Locate and replace the * watt resistors R14, R15, and R16 with watt resistors of the proper value per Table A-2.
3. Verify that integrated circuit U12 is P/N 167686-2. If not, refer to Field Change Notice FC-12/16-5 for instructions.
A-18
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