(b) Loosen the brass hex nut on the 

 toroid mounting stud to permit the toroid 

 assembly to be lowered and rotated clear of 

 the stirrer. 



(c) Remove the stirrer belt and stirrer 

 pulley. 



(d) Push the stirrer shaft down into the 

 bearing and remove the stirrer from the 

 bottom. 



(e) Clean out the bearing with lab tissue 

 or cotton swab. 



(f ) Clean the stirrer shaft and on model 

 RS-7A remove small O-ring, pack the groove 

 with Dow-Corning No. 44 bearing grease, in- 

 stall a new O-ring in the groove, and coat 

 the stirrer shaft with the bearing grease. 



(g) On newer models, equipped with ball 

 bearing assembly, pack with Dow-Corning 

 No. 44 bearing grease. 



(h) Reinstall the stirrer and be sure it 

 turns freely before replacing the pulley. 



(i) Install the pulley so that it exerts 

 gentle pressure on the bearing top to prevent 

 any vertical motion of the stirrer. 



(j) Replace the belt. Reposition the 

 toroid assembly. 

 4. Electrical problems. 



a. Instrument pilot light will not light when 

 main power switch is turned on. 



(1) Plug in instrument line cord or 

 check power source. 



(2) Check main fuse to the left of pilot 

 light. Replace if necessary. If fuse blows 

 again, do not replace. Investigate circuitry 

 for cause. Look for loose wire connections or 

 broken wires. Refer to wiring diagram in 

 instruction manual. Do not attempt any re- 

 pair on printed circuit boards or modular 

 components without the help of a competent 

 electronics technician. If repairs are made by 

 an electronics teclinician, log all changes 

 made. Return instrument to U.S. Naval 

 Oceanographic Office for further repair. 



b. Nulling meter will not respond to any 

 change of the Conductivity Ratio dials when 

 the instrument is turned on and the cell is filled 

 with sea water. Remove the chassis from the 

 case or remove back cover. Check and/or re- 

 place the fuses in the oscillator power supply 

 and the amplifier power supply. 



c. Stirrer motor does not operate. Check 

 stirrer motor wiring and stirrer switch. 



d. Pump motor is not operating. Check all 

 wiring to motor. Check pump switch. Check 

 fuse on lower left front panel. Replace one, or 

 all as necessary. 



e. Other electronic maintenance. For other 

 electronic trouble shooting and maintenance, 

 refer to the instruction manual. Do not attempt 

 any repair of electronic printed circuit hoards 

 or modular components loithout the assistance 

 of a competent electronics technician. 



1-25 Model 6220 Laboratory Salinometer. — 



The Model 6220 laboratory salinometer is 

 shown in figure 1-17. Generally, the preceding 

 operating instructions apply to this instrument 

 with the following exceptions : 



Figure 1-17. 



Laboratory salinometer, Model 6220, 

 Bissett-Bennan Corp. 



1. The power switch (I) is on the upper right 

 of the panel. 



2. The Function Selector switch (K) is on 

 salinity at all times except when depressed for 

 a temperature reading. 



3. The meter (G) on the model 6220 indicates 

 temperature °C. when the function switch is 

 depressed, eliminating the need for the Tem- 

 perature °C. knobs (M). Temperature compen- 

 sation is automatic, thus, eliminating the need 

 for Temperature Compensation dials (Q). 



4. The switch (N) is labeled Pump-Off-Stir 

 instead of Stir-Off-Fill. 



5. The Vacuum Control (F) and the Fill 

 Control (E) on the 6220 serve the same func- 

 tions as the Fill knob (F) and the Fill Control 

 (E) on the instrument ni figure 1-12. The finger 

 is placed over the Fill Control (E) on the 6220 

 to pump a sample. 



6. The Stopcock (P) is glass instead of 

 plastic. 



7. The Overflow jar (O) is plastic rather 

 than glass, and it can be emptied without remov- 

 ing it by opening a pinch clamp on the rubber 

 drain tube. 



8. The Standardizing Ratio Table (S) on 

 the panel lists the conductivity ratios for the 

 usual standards employed. 



The instruction manual furnished by the 

 manufacturer should be referred to if the in- 

 strument malfunctions. 



1-20 



