Section IV. MAINTENANCE (AVUM)

TM 55-4920-413-13&P Section IV. MAINTENANCE (AVUM) 4-6. Scope. The scope of corrective maintenance is the replacement of knobs, fuses, and indicator lamps and lenses, and the cable assemblies. 4-7. Fuse Replacement. a. b. c. d. 4-8. Make certain INPUT POWER switch is OFF. Disconnect LTS/VIDS from power source. Unscrew fuse holder cap and remove fuse. Insert new fuse and replace fuse holder cap. Knob Replacement. a. Loosen setscrew holding knob to shaft. b. Slide knob off shaft. c. Place new knob on shaft, making certain knob is fully on shaft and indexed correctly. d. Tighten setscrew. 4-9. Indicator Lamp Replacement. NOTE This applies to the seven warning lamps only. a. Make certain INPUT POWER switch is OFF. b. Remove lens cover. c. Remove lamp, d. Install new lamp, e. Replace lens cover. 4-10. Cable Assemblies. . Remove cable assembly from LTS case and ship to higher maintenance. 4-11. Lubrication. None is required. Section V. MAINTENANCE: Authorized REPAIR AND REPLACEMENT OF PARTS (ATST) NOTE Authorized repair of the IDSL Test Set by Avia- tion Intermediate Maintenance (ATST) personnel is indicated in Appendix B, Maintenance Alloca- tion Chart. NOTE Aviation Intermediate Maintenance (ATST) will perform only the authorized maintenance which in- cludes replacement and repair of components and end items which can be accomplished efficiently with available skills, tools, and test equipment. Evacuate, circuit boards, components and end items beyond capability of ATST to the Depot. cuits troubleshooting schematics FO-1 through FO-5. Do not replace circuit board if repair can be accomplished by authorized replacement of com- ponents on board. NOTE Remove Keying Plug from circuit boards before inserting extender board in assembly connector (Plugs in each circuit board). Be sure to reinstall keying plugs after maintenance has been completed. NOTE Place INPUT POWER switch OFF before remov- Perform Paras 4-12 and 4-13 as directed by ing or installing printer circuit boards and Troubleshooting Tables 4-5 through 4-17 and cir- connections. 4-3