HP-Service-Note-412A-5 电路图.pdf

412A-5 MODEL 412A/AR VOLTMETER-OHMMETER-AMMETER SERIALS 134-07482 AND BELOW INPUT CABLE MODIFICATION KIT J STOCK NO. 412A-95B Installation of this modification kit will prevent damage to the input cables by reducing the effects of excess strain. A s a result, you will experience longer and more reliable operation of the Model 412A/AR. Remove and discard bracket, This Service Note is written in two sections. The first section concerns kit installation instructions for cabinet model instruments. The second section It may be necessary to carefully separate concerns rack mount instruments. two resistors to remove the inside nut. 4. Using a 1/4,) drive ratchet wrench, 5/16) socket, and a short extension, remove the two 5/16” nuts which hold the tie point bracket to the main chassis. Note Special tools other than an electric drill and a 1/4” 5. Remove original input cables and boots from drive ratchet wrench with a 5/16) socket are not front panel. Do not discard the voltage cable required. assembly . PARTS SUPPLIED IN KIT 412A-95B 6. Install three new boots on the front panel. Quantity Description Stock No. 7. Install new tie point bracket using the original #6 bracket screws (Refer to Figure 1). 8. indicated in Figure 2. 1 Cable Assembly-Volt . . . . 412A-21D-1 Solder wires (not input cables) to tie points as 1 Cable Assembly-Common . . 412A-21E 1 Cable Assembly-Ohm-ma . . 412A-21F 6 1 Bracket, tie point . . . . . . 412A-12E of cable through boot. 1 Bracket, cable support, 1 Bracket, cable support, 3 Boot, cable. . . . . . . . . . 412A-83A nosed pliers may be used. 4 2 Hex Nut #6 . . . . . . . . . . 2420-0001 9. Install new ohms input cable by passing it through * * * * 428A-21A-1 the appropriate boot into instrument. Pull 12 inches (cabinet model) . . . . . . . 412A-12C 10. Place the cable-clamp halves together on ohms cable 2 inches back from stripped end. Pass cable through the appropriate hole in cable support bracket (rackmount model). . . . . 412A-12D and press clamps firmly into hole. Heavy needle- Machine screw, 6-32 x 3/8 BH, withlockwasher . . . . . . 2390-0009 11. Repeat steps 9 and 10 for new “volts” - and “common” cables. 12. Pull the cables forward through the boots. SECTION I, INSTALLATION INSTRUCTIONS CABINET MODEL 1. Remove cabinet and turn instrument on its top. 2. Remove shield on the function switch side of the instrument by removing the three #6 screws. 3. Unsolder all wires from the tie point bracket located on main chassis where the input cables enter the instrument. 01650-1 abcfg6p 13. Install the cable support bracket with #6 x 3/8 inch screws so that the plastic clamps are butted up to the boot mounting studs. Tighten the two screws. 14. Solder the input cable wires as shown in Figure 2. 15. Replace shield removed in step 2. 16. Replace instrument cabinet. 6-63 COMPLETE COVERAGE IN T - P A C K A R O C O M P v” $ 4 R O U T E O t S ,$C C U M : “H(WI4CU ELECTRONIC MEASURING EQUIPMENT * 0 A * * A A k a *&TO, C I L f P O R W t A , U . S . A . CADLI: “#WPAEU” TtL. (4 I S) t X I - T O O 0 j Pam?# I* u . . . * . RadioFans.CN 收音机爱 好者资料库 Page 2 412A-5 r TIE POINT BRACKET WA.LD-L.I-CI 8 CABLE SUPPORT BRACKET Figur 1. Exploded View of Model 412A Cable Support Assembly 17. Remove outer and inner probe sleeve from original volt cable as follows: a. Hold volt cable by the probe boot and loosen the sleeve locknut by turning it clockwise. b. Turn inner and outer sleeves (together) counter- clockwise and remove. c. Remove locknut noting that the threaded end came off first (it must be replaced in the same manner). d. Loosen the set-screw in the collar near threads with a 3/32 Allen wrench. e. Remove the shield assembly by turning counter- clockwise. 18. Reverse the procedures in step 17 to assemble the probe tip on the new volt cable. 19. Turn the instrument on and perform front panel checks. No re-calibration of the instrument is necessary. SECTION 11, INSTALLATION INSTRUCTIONS RACK MODELS 1. Remove the dust cover from the instrument. 2. Unsolder the input cable wires only at the tie points just behind input cable boots. Remove the input cables and boots from the front panel. Do not discard the voltage cable probe assembly. 3. Perform steps 9 through 12 in Section 1. 4. Refer to Figure 3. Position the cable support bracket by pulling on input cables so that the plastic clamps are aligned with the boot studs. Mark and then drill two #28 holes in the chassis using the cable support bracket as a guide. 5. Install the cable support bracket with #6 x 3/8 inch screws. Solder the input cable wires as shown in Figure 3. W 6. Perform steps 16 through 19 of Section I. 01650-1 RadioFans.CN 收音机爱 好者资料库 c:=4 412A-5 Figure 2. Model 412A (Cabinet Mount) Cable Support Assembly Page 3 Figure 3. Model 412AR (Rack Mount) Cable Support Assembly 01650-1 RadioFans.CN 收音机爱 好者资料库