HP-Service-Note-412A-8 电路图.pdf

- Qc1 - _ - - - - - -_ HEWLETT 1-PACKARD SERVICE NOTE 412A-8 Le( Model 412A/AR Voltmeter-Ohmmeter-Ammeter Serials 134-07482 and Below INPUT CABLE MODIFICATION KIT, PART NO. 00412-69501 Installation of this modification kit will prevent damage 5. Remove FUNCTION, POLARITY, and RANGE to the input cables by reducing the effects of excess knobs from the front panel using an Allen wrench. strain. The plastic cable clamps provided in this For ease of removaland replacement, set RANGE kit transfer the strain previously experienced at either switch to. 001 volt position before removing knobs. the cable boots or the tie points to the modified cable Remove the front panel. support bracket. As a result, you will experience longer and more reliable performance from the Model 4 12A/A R. discard (see Figure 3). 6. Remove old tie point bracket from chassis and This Service Note is presented in two sections. Section I contains insta1,lation procedures to be used with cabinet model instruments. Section I1 contains installation procedures to be used in conjunction with rack mounted models. No special tools are required to effect this modifi- cation. Either type of modification can be completed in approximately 2 hours. 7. Bolt new tie point bracket to chassis as illustrated in Figure 3. 8. Feed input cables through holes in the cable support bracket provided. There are two brackets includedwith this kit; one to beused with cabinet models, the other with rack models. Adjust cable clamps around the input cables and seat in place as illustrated in Figures 3 and 4. Insure t that at least two inches of cable is available to rear of plastic clamps. PARTS SUPPLIED IN MODIFICATION KIT, PART u 9. Whenplastic clampsare firmly seated, bolt cable support bracket to tie point bracket as shown in Figures 3 and4. Insure that forwardface of plastic cable clamp fits firmly against rear end of cable NO. 00412-69501 1 Quantity Part No. 1 Bracket, tie point. . . . . 412A-12E boot mounting studs as shown in Figures 3 and 4. i 1 Bracket, cable support (cabinet model). . . . . . 412A-12C 10. Solder the input cable wires as shown in Figure 4 . 1 Bracket, cable support CAUTION When unsoldering and soldering input cables 6 Clamp, cable . . . . . . . 428A-21A-1 to tie points, insure that cable shielding 2 Machine screw, 6-32 x (rackmount model). . . . 412A-12D 3/8 BH with lockwasher . 2390-0009 SECTION I. INSTALLATION INSTRUCTIONS FOR CABINET MODEL. 1. Remove cabinet and turn instrument on its top. 2. Remove shield on the function switch side of the instrument, 3. Unsolder all wires from the tie point bracket located on main chassis where the input cables enter the instrument (see Figure 1). 4. Remove the hexagonal nuts and screws indicated by arrows in Figure 2. strands do not penetrate cable insulation, thus grounding the element. 11. Replacefront panel by reversing steps #4 and 5 above. 12. Replace shield cover by reversing step #2 above. 13. Replace instrument cabinet. b SECTION I I . INSTALLATION INSTRUCTIONS FOR RACK MOUNTED MODELS. 1. Remove the dust cover from the instrument. 2. Unsolder the input cable wires at the tie points just behind the input cable boots (see Figure 5). i 1/65-9 Prlntsd n U.S.A I Customer Service 395 Page Mill Road, Palo Alto, California 94306. Tel. (4151 326-3950 e Europe: 54 Route Des Acacias, Geneva, Switzerland, Cable: HEWPACKSA Tel. (022) 12.81.50 8 RadioFans.CN 收音机爱 好者资料库 Page 2 R CONDUCTOR rp PINK/WHlTE MA-C-0143 Figure 1 3. Feed the cables through the holes in the cable support bracket providedand seat the plastic cable clamps as indicated in Figure 6. Refer to steps 8 and 9, Section I. 4. Position the cable support bracket so that the front face of the plastic cable clamp sits firmly against the rear end of the cable boot mounting stud. Mark and drill H28 holes in the chassis as indicated in Figure 6, using the bracket as a guide. 5. Fasten cable sup ort bracket to the chassis using the two 6-32 x 378 screws. 6. Solder the input cables as illustrated in Figure 6 , When unsoldering and soldering input cables to tie points, insure that cable shielding strands do not penetrate cable insulation, thus grounding the element, CAUTION 412A-8 7, Replace dust cover. Figure 2 RadioFans.CN 收音机爱 好者资料库 - - 412A-8 r Page 3 PLASTIC CLAMPS 4201-21A-1 CABLE SUPPORT BRACKET 5 12A-12C TIE POINT BRACKET /42A-I2E Y Figure 3 CENTER CONDUCTOR wnirr Figure 4 RadioFans.CN 收音机爱 好者资料库 Page 4 Figure 5 r CENTER CONDDUCTOR MAR-6-0147 s . L D 412A-8 Figure 0