HP-Service-Note-412A-6 电路图.pdf

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1、 41 2A-6 - I MODEL 412A DC VOLTMETER-OHMMETER-AMMETER RANGE SWITCH MAINTENANCE The following precaution should be exercised when or organic solvents such as tolulene, carbon cleaning the 412A VTVM range switches. The Pyro- tetrochloride, or chlorinated compounds may cause film resistors have a silic

2、on coating - be careful to the wafer material to swell, thus should not be used. not wash the silicon off these resistors when cleaning We recommend use of either Freon TF or a soap and warm water wash. The wash must be followed by a the range switch. If you should accidentally remove the silicon co

3、ating it may be reapplied by using complete rinsing, followed by a rinse with distilled Dupont Silicon Insulcone. wat%r and overnight drying in an oven at approximately 120 F. - 412A-19W and 412A-19W-1 (White Wafers) This switch should be cleaned with distilled water or with Freon TF and completely

4、dried off. Any other cleaning agents may contain harmful chemicals which could attack the wafer material causing it to crack or lose its high impedance characteristics. w You may notice some cracks in the range switch. These should be cleaned; however, the cracks themselves are not detrimental to th

5、e switch operation unless the wafer has been broken. When using the soap and water cleaning process, it is imperative that all residue be rinsed free of the wafers to eliminate leakage paths between wafer contacts which will show up as a defect in the instru- ment operation. Extreme caution should b

6、e used when handling the range switch after it has been cleaned to prevent oils from your hands contaminating the switch wafers. There is acid in this oil which can permanently etch the wafers in addition to creating a sticky surface on the wafer. White cotton gloves are recommended when handling th

7、e range switches. If you should have a drying oven available, you may use a detergent and warm water solution to wash the switch. This washing should be followed by avery complete rinsing - with distilled water as a last rinse - to insure that all impurities are removed from the switch wafers, follo

8、wed by an overnight dryingat approximately 120F. If a good rinse process is not used, there is a possibility of impedance leakage There is no need to lubricate the rotors or contacts paths between contacts on the wafer which willshow on the switch wafers. Any lubrication applied to the up as a defec

9、t in the instrument operation. wafers will cause dirt to stick and could create a leakage path for possible malfunction. Lubrication The detent assembly should have a small amount of lubricationapplied to it following the cleaning process . 412A-19A and 412A-19B (Green Wafers) This range switch cont

10、ains wafer material which is the most recent available. There are many cleaning stock numbers for recommended material: agents which may be used. Cleaning agents containing soap, acetone, Freon TF or PC and ethanol will not attack this switch. Any Freon TF, 16 oz. spray can. , . 8500-0232 Lubriplate

11、, 1/2 oz. tube. . , . , 6040-0018 cleaning agent containing weak acids,weak alkalies, Gloves, white cotton . . . , . , . 8650-0002 L 1 8/64-9 I . . P COMPLETE COkRAGE IN H W L E T rp: p A C K A R D c 0 5 4 R O U T E D GINEVA, L W C M LE: In IWPAC USA* ELECTRONIC MEASURING EQUIPMENT 1 s o I M t L t : R o A D P A L O A L T O , C A L I F Q R N ! . , U . S . A . P A G c CAILCt “HCWIACK” TeL, (4 I SI J 1 6 - 7 0 O D PRINT10 I 4 Y S A &a - . - RadioFans.CN 收音机爱 好者资料库