INSTALLATION MANUAL FOR 2U MODIFICATION KIT

Transcription

1 FOR 2U MODIFICATION KIT Kit for modification of ARC Type 385A Communication -Navigation System; (Extended COM Frequency Range: to MHz) Publication. No. 86M016 OCTOBER 1992

2 LIST OF EFFECTIVE PAGES Issue Page Affected Date Title A 10/13/92 2 C 1/27/93 3 C 1/27/93 4 C 1/27/93 5 A 10/13/92 6 A 10/13/92 7 B 12/10/92 8 C 1/27/93 9 A 10/13/92 10 A 10/13/92 11 A 10/13/92 12 C 1/27/93 13 B 12/10/92 14 A 10/13/92 15 A 10/13/92 16 A 10/13/92 17 A 10/13/92 18 A 12/10/92 Page 2 Rev. C

3 TABLE OF CONTENTS Section Title Page - Title 1 - List of Effective Pages 2 - Table of Contents 3 - List of Figures 4 - List of Tables General Information Purpose for Instruction Manual Affected Radios Special Tools or Equipment Required Reference Theory of Operation Kit Installation Procedures Disassembly IC and Capacitor Removal Mod Board Installation Switch Removal Replacement Switch Installation Resistor Installation Assembly Alignment Mod Decal Part Number Decal Illustrated Part Identification 11 Page 3 Rev. C

4 LIST OF FIGURES Figure Number Title Page 2-1 Modification Decal and Part Number Decal Placement COM Synthesizer Board (A3A1/A3) Before Modification COM Synthesizer Board (A3A1/A3) with Mod Board Installed NAV Synthesizer Board (A2A1/A2) Before Modification NAV Synthesizer Board (A2A1/A2) with Resistor Installed U Modification Kit Assembly, P.C. Board, 1V Modified Schematic, COM Switching for S/N to 39, Modified Schematic, Terminal Count for S/N to 39, Modified Schematic, COM Switching for S/N 40,000 and Above Modified Schematic, Terminal Count for S/N 40,000 and Above Modified Schematic, Terminal Count for COM Synthesizer Boards Revision 14 and Earlier 18 LIST OF TABLES Table Number Title Page 1-1 Modified COM MHz Select Data U Modification Kit V P.C. Board Assembly 13 Page 4 Rev. C

5 SECTION I GENERAL INFORMATION 1.1 Purpose of Instruction Manual The purpose of these instructions is to provide a brief description of the extended frequency range modification procedures for the ARC RT-385A Communication-Navigation Radio. Existing radios tune the frequency range of to MHz. After the modification kit is installed, the RT- 385A will tune to MHz. The replacement parts are Sigma Tek, Inc. kit part number 2U Section III of this manual contains illustrations of the kit parts and a parts breakdown of the modification board. This information can be used for future reference, should it become necessary to replace a defective component in the kit. A copy of this instruction manual should be inserted in the maintenance manual(s) of the affected ARC radio(s). 1.2 Affected ARC Radios RT-385A Series COM/NAV 1.3 Special Tools or Equipment Required Installation of 2U kit requires no special tools or test equipment. Standard equipment such as a soldering iron, desoldering equipment, pliers, wire cutters, screw drivers, etc. is all that is necessary for installation. 1.4 Reference 300 NAV/COM Type RT-385A Service/Parts Manual - P/N , Revised Issue, March 15, 1982 (Serial Nos. Through 39,999); 300 NAV/COM Type RT-385A Service/Parts Manual - P/N , Change 1, May 1986 (Serial Nos. 40,000 & Higher). The synthesizer boards are numbered as follows: S/N up to 39,999: COM Synthesizer Board is A3A1 and NAV Synthesizer Board is A2A1. S/N 40,000 and up: COM Synthesizer Board is A3 and NAV Synthesizer Board is A2. For the purpose of this installation manual, the COM Synthesizer Board is referenced (A3A1/A3) and the NAV Synthesizer Board is referenced (A2A1/A2) corresponding to (serial numbers through 39,999/serial numbers 40,000 and above), respectively. 1.5 Theory of Operation A) COM MHz Switch - Replacement switch accomplishes the following: 1) Display control is changed to send the 6 in 136 MHz at the appropriate position. The existing selector switch has 18 positions for COM frequencies of 118 to 135 MHz. The replacement switch has 20 positions for 118 to 136 MHz plus one extra position. Sigma Tek, Inc. has decided to place 136 MHz in the extra position. 2) Two pins are added, T9 and T9A, to the section 1, front part of the switch. These pins function as tuning voltage connections. For modified schematics see Figure 3-3 and Figure ) COM MHz select data from section 2, front (synthesizer) is changed. 136 MHz is the zero preset instead of 135 MHz as in standard frequency range radios. This changes the COM MHz Select Data Table (Table 4-1 for serial numbers up to 39,999; and Table 5-5 for serial numbers 40,000 and above) as shown in Table 1-1: Page 5 Rev. C

6 MHz Input (Binary) EDCBA Table 1-1 Modified COM MHz Select Data Transmit Receive Frequency Clocks from Frequency Clocks from (MHz) MTC to MTC (MHz) MTC to MTC 118.xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx xxx B) Tuning Voltage - The function of the new resistor (R88A) is to provide an extra tuning voltage The modified circuit is designed to add the extra voltage at the bottom of the frequency range. Old voltages will be shifted up one MHz channel frequency. The new tuning voltages are as follows: Frequency (MHz) Tuning Voltage Vdc 119, Vdc 121, Vdc 123, Vdc 125, Vdc 127, Vdc 129, Vdc 131, Vdc 133, Vdc 135, Vdc (These values replace the old values listed in Section 5, COM Tuning Voltage Test, of the Service/Parts Manual). See Figure 3-3 and Figure 3-5 for modified schematics. C) Terminal Count - Changes in the terminal count circuit are as follows: Original: Master terminal count is 230 for transmit and 251 for receive. 135 MHz is a zero preset on the counter input. Modified: Master terminal count is 231 for transmit and 252 for receive. 136 MHz is a zero preset on the counter input. These changes are physically incorporated on the 1V Modification Board. See Figure 3-4 and Figure 3-6 for modified schematics. Page 6 Rev. C

7 SECTION II KIT INSTALLATION PROCEDURES 2.1 Disassembly Disassemble affected radio to gain access to U13, U26, C178, and C179 on the COM synthesizer PC board (A3A1/ A3), using procedures described in the appropriate maintenance manual. Important: Find and note the revision number of the COM synthesizer PC Board. If the revision level is 14 or below, the unit will need a mod board marked 56B REV B. 56B REV A MOD BOARDS WILL NOT WORK IN UNITS WITH COM SYNTHESIZER PC BOARDS REVISION 14 OR LOWER. 2.2 IC and Capacitor Removal Remove IC's (U13 and U26) and capacitors (C178 and C179). (Older units will not contain C178 and C179) See Figure 2-2. Remove all solder from the IC holes on the PC board. Clean affected area and inspect for pieces of solder residue. On COM synthesizer boards without a solder mask, a thin urethane insulating coat (Hysol type PC18 or urethane equivalent) should be brushed onto the affected area excluding the IC pads. 2.3 Mod Board Installation (Mod Kit P/N 1V ) Note: If the unit contains a COM synthesizer board marked revision 14 or lower, change the Mod Board as follows: Remove the jumper connecting point "x" to point "1". Place a new jumper (gage 24 or smaller) from point "x" to point "2". See figure 3-2. Insert and solder the Modification Board. See Figure 2-3. Reinstall the COM synthesizer cover. 2.4 Switch Removal Remove the front panel as described in the appropriate maintenance manual. Unfasten the transmitter assembly (A4) from the main assembly. Remove the power supply assembly (A5) from the unit. This will provide enough room to remove the switch. Carefully desolder the COM MHz selector switch pins from the NAV synthesizer PC board. See Figure 2-4 of this manual. Next, desolder the switch mounting bracket. Ensure that all joints are free of solder and carefully remove the switch. Note: Use extreme care in this portion of the procedure. Damage to any of the PC board pads will result in costly repairs. 2.5 Replacement Switch Installation (Mod Kit P/N ) After the old switch has been removed, ensure that all pads are free of solder. There are two more pins on the new switch assembly that were not on the old switch, their holes must be opened. Clean and inspect the board and insert the new switch. Make sure that all the pins are in the holes and that the switch is pressed all the way down onto the board. Solder the switch in place. Page 7 Rev. C

8 2.6 Resistor Installation (Mod Kit P/N ) Install the new resistor (6810 ohms) on the back of the NAV synthesizer board. Install the resistor from one of the two extra COM MHz switch pins and the junction of R88, R89, R90, and R91. See figure Assembly Reinstall power supply assembly and fasten transmitter assembly. Assemble as specified in the radio maintenance manual. 2.8 Alignment Align radio as specified in the appropriate Service/Parts Manual. Ensure the VCO locks in properly at MHz and at MHz.Align VCO if necessary. (See Service/Parts Manual Section 5, under COM Synthesizer Alignment). Align the Transmitter and the COM Receiver using MHz for low-band, MHz for mid-band, and MHz for upper-band. (See Service/Parts Manual Section 5, under COM Receiver Alignment and Adjustment). 2.9 Mod Decal (Mod Kit P/N 66A ) Note: Before placing decals, clean affected areas with alcohol. Place the Mod Decal underneath A2A1P1 on the back of the radio. Stamp out mod level "15" on the existing mod plate. See Figure 2-1 for Mod Decal placement Part Number Decal (Mod Kit P/N 66A ) Place the Part Number Decal over the first four digits of the unit dash number. For units with dash number 1000 use Part Number Decal 1001; for units with dash number 1100 use Part Number Decal See Figure 2-1 for Part Number Decal placement (see Detail A). Figure 2-1 Modification Decal and Part Number Decal Placement (view is from back of unit) Page 8 Rev. C

9 Figure 2-2 COM Synthesizer Board (A3A1/A3) Before Modification (component side) Figure 2-3 COM Synthesizer Board (A3A1/A3) with Mod Board Installed (component side) Page 9 Rev. A

10 Figure 2-4 NAV Synthesizer Board (A2A1/A2) Before Modification (solder side) Figure 2-5 NAV Synthesizer Board (A2A1/A2) with Resistor Installed (solder side) Page 10 Rev. A

11 This section contains a schematic of the components in Sigma Tek's 2U kit. Also contained is the illustrated parts breakdown of this kit. Should it become necessary to order replacement parts for the 2U kit, contact SIGMA TEK, INC. at the address shown below. SECTION III ILLUSTRATED PARTS IDENTIFICATION Please specify that the parts being ordered are for use on an ARC radio and give the radio model number, serial number and mod level. SIGMA TEK, INC. ARC PART SALES DEPARTMENT 1001 INDUSTRIAL ROAD AUGUSTA, KANSAS TEL. NO OR TELEX NO FAX. NO Page 11 Rev. A

12 Table 3-1 2U Modification Kit Fig-Item Part Number Qty Description V Assembly, P.C. Board Resistor, 6.81k, 1/4 W, 1%, R88A A Mod Decal A Part Number Decal COM MHz Selector Switch Figure U modification kit Page 12 Rev. C

13 Table 3-2 1V P.C. Board Assembly Fig-Item Part Number Qty Description B Printed Circuit Board S Pin S10035-C102K2XHNT 2 Capacitor, Ceramic Chip S LS157M, IC, Quad Multiplexer S LS30M, IC, 8-input NAND Gate Figure 3-2 1V P.C. Board Assembly Page 13 Rev. C

14 Figure 3-3. Modified Schematic, COM Switching for S/N to 39,999. Schematic shows replacement switch (S1) and additional tuning resistor (R88A). See Sheet 2 schematics in the Service/Parts Manual. Applies for all Mod Levels. Page 14 Rev. A

15 Figure 3-4. Modified Schematic, Terminal Count for S/N to 39,999. Schematic shows replacement and rewiring of U13, U26, C178, and C179. Refer to Service/Parts Manual Schematics (Sheet 2). Applies for all Mod Levels. Page 15 Rev. A

16 Figure 3-5. Modified Schematic, COM Switching for S/N 40,000 and Above. Schematic shows replacement switch (S1) and additional tuning resistor (R88A). See Sheet 2 schematics in the Service/Parts Manual. Applies for all Mod Levels. Page 16 Rev. A

17 Figure 3-6. Modified Schematic, Terminal Count for S/N 40,000 and Above. Schematic shows replacement and rewiring of U13, U26, C178, and C179. Refer to Service/Parts Manual Schematics (Sheet 2). Applies for all Mod Levels. Page 17 Rev. A

18 Figure 3-7. Modified Schematic, Terminal Count for COM Synthesizer Boards Revision 14 and Earlier. On original schematics C178 and C179 are not shown. Schematic shows replacement and rewiring of U13 and U26. Page 18 Rev. A