Best results are obtained if the first half of 

 a fix signal is viewed with suspicion and great- 

 est weight is given the latter portion of the trace 

 wlien the ship's heading, the electrochemical 

 system of the electrodes, and the capacitors in 

 tiie wave-signal suppressor system have all had 

 time to come to equilibrimn. Although instru- 

 ment zero lies in the center of the chart paper, 

 the electrode zero point does not necessarily 

 coincide with the instrument zero point, unless 

 adjusted by the electric zero control. 



M-34 Computing the Current Fix.— To 



compute the current fix, complete oceano- 

 graphic log sheet— GEK, using the values ob- 

 tained during the run and the equations given 

 on the log sheet. 



M-35 Securing the GEK.— After a current 

 fix, secure the instrument by turning the 

 PAPER MOTOR switch (B) and the 

 POWER switch (A) to OFF (DOWN) posi- 

 tion In addition move FILTER SHORTING 

 switch (G) to the CAP. SHORT position. This 

 short circuits the capacitors and releases any 

 accumulated dielectric strain. If the ship is to 

 be stopped before taking the next current fix, the 

 cable also must be retrieved. In the case of a 

 long cessation of operations, the AC power 

 supply should be unplugged from the recorder, 

 and the automatic current adjuster should be 

 taken out of the operating (standard cell) posi- 

 tion, by unlatching the chart -drive-reroll and 

 releasing the standard cell connection. 

 M-36 Maintenance of the GEK.— Both 

 routine and special maintenance for the record- 

 ing unit are described in detail in the direction 

 manual supplied with the instrument. 



1. Tlie parts of the recorder are easily acces- 

 sible. The door opens wide to the left. The chart- 

 drive-reroll unlatches to swing out to tlie right, 

 bringing the chart to a handy position for re- 

 placement and exposing the main slidewire. 

 With or without the chart-drive-reroll latched in 

 place, the entire assembly swings out around the 

 same hinge makiiig the balancing motor, paper- 

 drive motor, standardizer, and dry cell com- 

 pletely accessible. Amplifier, fuses, and terminal 

 boards are then exposed on the back of the re- 

 corder case. To inspect the amplifier, remove 

 tlie entire unit from the case. 



2. A roll of strip-chart paper is 120 feet long. 

 It is driven at a speed of Vs inch per minute; 

 consequently, it should last for about 5 days of 

 continuous operation. Note how the roll in the 

 instrument is threaded through the guides so 

 that the fresh roll can be threaded properly 

 when it is necessary to change rolls. Sometimes 

 tlie paper on the takeup roll tends to bunch or 

 bind at one end. This can be straiglitcned by ad- 



justing the thumbscrew at the left end of the 

 feed roll until both edges of the paper line up in 

 the slot cut in tlie platen abo^-e the telltale wheel 

 at the right. Badly bunched paper sliould be re- 

 rolled before adjusting the thumbscrew. 



3. If the pen stops inking while it still con- 

 tains ink, moisten a finger and draw it across the 

 penpoint. If this fails to start the flow of ink, re- 

 move the pen from the carriage, and push a fine 

 wire through the point to clean out any par- 

 ticle clogging it. If the ink still does not flow, 

 install a new pen. Place the clogged pen in al- 

 cohol or liot water for an hour or so. Remove 

 the pen from the solution, and insert a cleaning 

 wire as previously directed. Then fill the pen 

 with alcohol or warm water, and blow the liquid 

 out through the penpoint. Allow the pen to dry 

 thoroughly before using. 



4. In case of cable and/or electrode failure 

 the entire unit of cable with electrodes must be 

 replaced. Since the electrodes are matched and 

 balanced very carefully, any damage to one elec- 

 trode requires replacement of botli. However, 

 fish bites or cable insulation leaks can be re- 

 paired with rubber tape and covered with elec- 

 tronic tape. 



To check the cable while underway, first, 

 place a ^•oltmeter between one of the cable leads 

 and groiuid. The meter should read between 0.5 

 to 0.7 volts. No voltage indicates a break in the 

 cable or an electrode failure. NOTE: Never 

 place an ohmmeter across the cable leads. 



5. The junction box, where the cable plugs 

 into the recorder line, usually is located in a 

 relatively exposed position. It must be kept dry 

 and clean as it is likely to be the principal source 

 of instrument failure. 



6. To insure proper operation of the GEK, 

 always be certain that : 



a. The conductor leading from the more 

 distant electrode (black lead wire in the elec- 

 trode string) is connected to the positive input 

 terminal when operating in the northern 

 hemisphere (see paragraph M-28) . 



b. The dry cell in the recorder is in good 

 condition. A small indicator at the left edge 

 of the strip chart shows a red signal when a 

 new dry cell is needed ; however, if any diiE- 

 culty is experienced in zeroing the pen, in- 

 stall a new dry cell even though the red signal 

 is not showing. 



c. The junction box is dry and its contact 

 bright. 



d. The cable is plugged in properly at the 

 junction box when the instrument is in 

 oj^eration. 



e. The recorder is not stopped for an ex- 

 tended period with the automatic current 

 adjuster in the operating (standard cell) 

 position. 



M-24 



Change 1—1970 



U.S. GOVERNMENT PRINTING OFFICE ; 1970 O — 355-756 



