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*CHAPTER 12

BACKUP COMPUTER SYSTEM



12-1. BUCS CONFIGURATIONS

The BUCS has two configurations--the BUCS General and the BUCS Special. The quantity and configuration authorized to survey elements are shown in Table 12-1.

a. BUCS General. The BUCS General consists of the HP71B computer, a carrying case, and reference material. The HP71B is powered by four AAA 1.5-volt batteries or through an AC adapter by 120- or 240-v AC current. The average battery life of the four AAA batteries is 60 hours. The HP71B can perform rapid and accurate calculations. The computer has an operating system that accepts any RAM or read-only memory (ROM) combination to a maximum of four plug-in custom or prewritten memory modules. It has a continuous memory that can be expanded with the use of plug-in memory modules. The continuous memory allows the operator to turn the computer off and later resume operation without losing memory programs or the previous program calculations. The HP71B has a liquid crystal display that can display up to 22 characters. The contrast of the display characters and annunciators and the viewing angle are adjustable. The computer can function as a perpetual clock and/or calendar.

b. BUCS Special. The BUCS Special consists of the HF71B computer, the HP2225B ThinkJet printer, the interface cable, the HP-IL 82401A interface module, the HP2225B battery pack, a 120-volt and a 240-volt AC adapter, the carrying case, and reference material. (See Figure 12-1.) The ThinkJet printer is designed for portability. It is powered by a rechargeable battery pack or by a 120- or 240-v AC adapter. The print head cartridge in the ThinkJet printer is disposable and easy to replace. The printer is designed to print on standard 8.5-by 11-inch or European size A-4 single-sheet or fanfold paper. It can print 150 characters per second, print bold characters, and underline in four print pitches.

12-2. ALPHANUMERIC KEYBOARD FUNCTIONS

Most keys on the computer perform one primary operation and two alternate operations. The primary operation of any key is indicated by the white or black character(s) on the face of the key. The alternate operations are indicated by the gold characters printed above the keys and the blue characters below the keys. To select the character or operation printed on the face of a key, press only that key. To select the alternate character or operation printed in gold and blue, press the like-colored prefix key f or g and then the operation key. The functions of each key are described in TM 9-7000-200-13&P and the HP71B Reference Manual.

12-3. STATUS ANNUNCIATORS

Table 12-2 lists and briefly describes the status annunciators.

12-4. PREPARATION FOR BUCS OPERATION

a. BUCS Operating Precautions. Certain electronic circuits in the computer function continuously. Improper operation can disrupt performance in unexpected ways or damage the electronics. Observe the precautions below in assembling or operating the BUCS General or BUCS Special.

(1) When installing batteries or RAM or ROM modules, the operator must ground himself to metal to remove static electricity from the computer. This is particularly important for the handling of the HP-IL 82401A interface module.

(2) Turn the computer off before installing or removing batteries. When removed, the batteries must be replaced within 30 seconds or the contents of the computer memory are lost. If the AC adapter is connected to the computer, the memory will not be lost when the batteries are changed.

(3) Turn the computer off before installing or removing plug-in modules. Memory loss will occur if the interface module or a RAM or ROM module is removed when the computer is on.

(4) Turn the computer and printer off before connecting or disconnecting the interface cables to either component.

(5) Do not place the computer in strong magnetic fields (for example, near a telephone).

(6) Do not place fingers, tools, or other foreign objects into any of the computer plug-in ports.

(7) Place the printer on a clean and level surface for operation.

b. BUCS Turn-On and Turn-off Procedures. To place the computer in operation, press the ON key. To turn the computer off, perform one of the following:

  • Press the f key and then the ON key.
  • Type in OFF, and press the END LINE key.
  • Type in BYE, and press the END LINE key (only in basic mode).

Note. A power supply safeguard automatically turns the computer off with loss of memory after 10 minutes of inactivity.

c. BUCS General Assembly. To use the BUCS General for survey computations, perform the steps discussed below.

(1) Ensure the computer is off. No prompts or characters should appear in the display window.

(2) Turn the computer upside down, and set it on a soft, flat surface.

(3) Using your thumb, press down on the battery compartment door (the door to the center compartment). Slide the compartment door toward the rear of the computer. When you press down on the compartment door, the catch will snap as it unlatches from the computer.

(4) Insert the batteries. Be careful to align the batteries according to the indicators in the compartment. (See Figure 12-2.)

(5) Lay the compartment door imposition. Slide it toward the front of the computer until the catch snaps.

(6) Insert and secure the program ROM module in the appropriate plug-in port on the computer. Port 1 is the preferred port to use. If port 1 is in use, take the next numbered port. (See Figure 12-3.)

CAUTION

Inserting or retrieving the program ROM module while the computer is on can damage the module and/or cause the display to be frozen.

d. BUCS Special Assembly. The computer for the BUCS Special is assembled in the same manner as that for the BUCS General. To use the printer with the computer, follow the procedures discussed below.

(1) Insert and secure the HP-IL 82401A interface module in the appropriate plug-in port on the computer. (See Figure 12-4.)

(2) Connect the interface cables to the interface module connectors of the computer. (See Figure 12-5.)

(3) Connect the interface cables to the printer interface connectors. (See Figure 12-6.)

(4) Insert the battery pack into its slot on the printer. Push the battery pack inward until the latch snaps shut.

(5) Insert the AC adapter plug into the receptacle on the battery pack; then connect the AC adapter to the AC power source.

(6) To turn the printer on, press the POWER switch to the 1 position. The PWR light should be on.

(7) Open the front cover of the printer, and pull back the carriage latch. Insert the paper ink absorber into its holder. Insert the print head cartridge into the carriage. (See Figure 12-7.)

(8) Close and snap the carriage latch, and pull the bail arm back. Install the paper separator onto the printer, and raise it to the vertical position. (See Figure 12-7.)

(9) Insert the paper, and slide it along the paper channel into the slot under the paper separator. Pull the top edge of the paper ¼ inch above the bail arm rollers.

(10) Align the right-hand pinwheel to the paper holes, and push the bail arm forward. Lower the paper separator to the operating position, and close the printer cover. The BUCS Special is now ready for operation.

e. HF71B Computer Operational Self-Test. The self-test can be conducted with or without the AC adapter. If you suspect that the computer is not operating properly, perform the self-test as specified below.

Note. It is advisable to perform the self-test after prolonged periods of storage or when installing new batteries and/or ROM modules.

    (1) Turn the computer off.

    (2) Remove all custom or prewritten program ROM modules from the computer. Reinsert the plug-in port covers into the computer plug-in ports.

    (3) Plug the AC adapter into the receptacle on the back of the computer. Connect the AC adapter to an AC power outlet.

    (4) Turn the computer on.

    (5) Type PI, and then press the END LINE key. The result 3.14159265359 should be displayed, which indicates that about 60 percent or more of the computer circuits are operating properly.

    (6) If the computer repeatedly fails to perform a particular operation or repeatedly displays an error message, such as EXCESS CHARS, carefully reread the instruction regarding that operation. You may be improperly specifying the operation.

    (7) If the computer still does not operate properly, press the ON key and / key at the same time. INIT:1 will appear in the display. Press the END LINE key to execute a Level 1 initialization. The display should now display the replace cursor (BASIC mode) or insert cursor (CALC mode).

    (8) Press the ON key and / key at the same time. Then press the 2 key and END LINE key. This executes a Level 2 initialization (INIT: 2). The computer will do a self-test of its circuitry and will display ROM TEST 1 as it begins to test the circuits. When the first portion of the test verifies the proper operation of the circuits, the computer will display ROM TEST 1G 2. This indicates that the computer is continuing the test. When the test is completed, the computer will display ROM TEST 1G 2G 3G 4G. Then it will return to the BASIC mode if the test revealed no faulty circuits. If faulty circuits are detected, at least one of the numbers will be followed by a B instead of a G. Thus, ROM TEST 1G 2B 3G 4G indicates that the computer has a faulty ROM. If the computer indicates a faulty ROM after an INIT: 2 test, it requires service.

    (9) If the display remains blank when the ON key is pressed, or if characters remain "frozen" in the display, then reset the memory by using the procedure below.

      (a) Press and release the ON and / keys at the same time.

      (b) The display prompts INIT: 1. All keys are now inactive except 1, 2, 3, and END LINE. To reset the memory, press the 3 and END LINE keys.

      (c) The display prompts MEMORY LOST. Clear the display by pressing the ON key.

    (10) If the procedure outlined in (9) above did not solve the problem, reset the memory as discussed below.

      (a) Unplug the AC adapter, and turn the computer off.

      (b) Remove all modules.

      (c) Remove the batteries.

      (d) Press and hold down the ON key for about 30 seconds to discharge the circuits.

      (e) Install the batteries, or connect the AC adapter. Then press the ON key. The message MEMORY LOST should appear in the display. Pressing any key should display the BASIC prompt and replace the cursor.

f. HP2225B ThinkJet Printer Operational Self-Test. If you suspect that the printer is not operating properly, perform the self-test in the order specified below.

(1) Turn the HP2225B printer off.

(2) Depress and hold the line feed (LF) button while turning the power switch on.

(3) Release the LF button to start the self-test sequence.

(4) You can terminate the self-test at any time by turning the printer off.

12-5. SURVEY PROGRAM MODULE

The survey programs in the survey program module are user-friendly. The user is guided through each program by numerous prompts that are simple and understandable. The prompts displayed must be followed step-by-step to determine the correct data or solution in that program. The known or field data required for computer computations are the same as those required for manual computations. Survey data and computations may be recorded on the appropriate computation forms developed for use with the computer or recorded directly by the printer when the BUCS Special computer is used. The prompt abbreviations are explained in the Glossary and in the instructions section of each form.

Note. Record data exactly as shown on the display. Computations will be rounded off only before survey data are passed to the user.

a. Initial Turn-On. To activate the survey module for the initial turn-on, type RUN SURVEY; then press the END LINE key. The display shows SURVEY PGM MENU REV1. After the initial turn-on, the user need only press the RUN key to call up the survey program menu. Anytime the survey module is removed, the initial turn-on procedure applies.

b. Program Selection. Two different procedures can be used to select a program from the survey module.

(1) Follow the steps in Table 12-3 to call a program for which the program or module number is known.

(2) Follow the steps in Table 12-4 to call a program for which the program or module number is unknown.

c. Survey Program Menu. Table 12-5 is a complete list of the programs contained in the menu as each appears in the display.

d. Program Functions. The operator can back up to or recall a previous display, or he can go to the top of a file and review the entire program. He can correct data, if required, by entering the correct data. The operator can abort a survey program at any time. These capabilities are inherent to the survey program software.

(1) Backup. To back up to a prior prompt or data display, press the B and END LINE keys. To back up to each previous prompt or data display, repeatedly press the B and END LINE keys.

Note. Specific display prompts are preceded by a circumflex (^). The circumflex is used with the backup function. It tells the operator performing the backup operation that some data have been bypassed. To review the bypassed data, the operator must proceed in the program. In the following example, Program 1, Azimuth and Distance, is used to demonstrate the backup procedures when a prompt with a circumflex is displayed.

(2) Top of file. To go back to the beginning of a program, press the T (top of file) and END LINE keys. This allows the operator to review the entire program and check the data displays to ensure correct information was entered.

(3) Error correction. After performing a backup of a prior input, the operator can correct input data by entering the corrected data where the error exists. Key in the correct data, and press the END LINE key. To recompute all outputs by using the corrected data, press the END LINE key as required.

(4) Abort. The operator can abort a survey program at any point in the program calculation by pressing the A and END LINE keys. A safety prompt, ABORT (Y/N), is displayed to preclude accidentally aborting a program. To complete the abort procedure, press the Y and END LINE keys. The next display prompt will be SURVEY PGM MENU REV1.

(5) Warning messages. Table 12-6 lists the warning messages that may be encountered in the survey programs.

12-6. SURVEY PROGRAMS

a. Program 1--Azimuth and Distance. This program computes the grid azimuth and distance between two known stations. The user must input the known UTM coordinates of both stations. Computations are recorded on DA Form 5590-R.

b. Program 2--Traverse. This program computes the grid azimuth, coordinates, and height of up to 40 main scheme traverse stations from the known data of the starting station and the field data of the traverse. Offset stations (doglegs) are not included. The program converts slope distance to horizontal (sea level) distance and computes total traverse length, total azimuth and height corrections, radial error of closure, and accuracy ratio. (See Appendix B for accuracy requirements.) It also computes traverse adjustment. A sketch of a sample traverse is shown in Figure 12-8. The known data and field data to be used in computation of this traverse are recorded on DA Form 5591-R. The closure and adjustment data are recorded on the reverse of DA Form 5591-R. The data for a dogleg cannot be recalled for correction or review after the prompt AZ TO REAR: 0.000 is displayed and the END LINE key is pressed (step 6).

c. Program 3--Triangulation. This program computes coordinates, height, azimuth, and distance by triangulation. It will compute a single triangle or a chain of triangles up to 40 triangles. Data for triangulation computations are recorded on DA Form 5592-R.

d. Program 4--Resection. This program computes the coordinates and height of one or more stations from the UTM coordinates of three known stations. Resection computations are recorded on DA Form 5593-R.

e. Program 5--Altitude Method. This program computes a grid azimuth from three sets of observations of the sun or a survey star. The program contains two separate computations--one for sun and one for stars. Computation of the sun altitude is recorded on DA Form 5594-R. Computation of star altitude method is recorded on DA Form 5595-R. Azimuth from three sets of observations are computed, and the azimuth of each set is compared to the mean of the three sets. If one of the three sets does not meet the rejection criteria, the computer will display SET #_REJECTED. The computer will then calculate a mean azimuth from the two remaining sets. Should two sets fail to meet accuracy specifications, the display will be REJECT CRIT NOT MET. In this case, check the input data and recompute. If rejection criteria still arc not met, determine new field data.

CAUTION

Once the user has obtained the final grid azimuth and it is shown in the GRID AZ/MK display, the backup function cannot be used. To review any previously entered data, the operator must use the top of file function (press T and END LINE keys). The backup function can be used at any time before the final grid azimuth is shown in the GRID AZ/MK display.

f. Program 6--Hasty Astronomic Observation (Hasty Astro). This program computes a grid azimuth and check angle from observations of the sun or a survey star. Data for either operation are recorded on DA Form 7286-R. The accuracy of the computation depends on the instrument used to perform the observation (0.3 mils for the T16). The program uses the electronic ephemeris, which eliminates the need to extract data from FM 6-300. The program provides the option of using the internal timer to determine date and time of observation or manually inputting date and time. The ability to manually input date and time of observation allows the surveyor to perform fieldwork without BUCS being at the site of observation.

g. Program 7--Star ID. This program computes the approximate azimuth and altitude to a selected star at a date and time chosen by the user. The orientation data will help identify survey stars for astro observation or navigation. The program will compute the approximate azimuth and altitude (vertical angle) to any of the 73 survey stars listed in FM 6-300. The orientation data are accurate to 5.0 mils. Data for Star ID are recorded on DA Form 7284-R. The form has space for six sets of data.

h. Program 8--Polaris Tabular Method. This program computes a grid azimuth from three sets of observations of Polaris by using the Polaris tabular method. Computations are recorded on DA Form 5598-R. This program checks the accuracy specifications in the same manner as Program 5.

i. Program 9--Grid Convergence. This program computes a UTM grid azimuth from a gyroscopic (true) azimuth. Computations are recorded on DA Form 5599-R.

j. Program 10--Conversion and Transformation. This program has three separate operations which are described below.

(1) Geographic to UTM. This operation computes conversion of geographic coordinates to UTM coordinates. Computations are recorded on DA Form 5600-R. This operation requires the following data:

  • Spheroid.
  • Latitude of station.
  • Longitude of station.
  • Grid zone.

(2) UTM to geographic. This operation computes conversion of UTM coordinates to geographic coordinates. Computation are recorded on DA Form 5601-R. This operation requires the following data:

  • Spheroid.
  • UTM easting.
  • UTM northing.
  • Grid zone.

(3) Zone to zone. This operation transforms UTM grid coordinates and grid azimuth from one grid zone to an adjacent grid zone. Computations are recorded on DA Form 5602-R. The operation requires the following data:

  • Spheroid.
  • Starting grid zone.
  • Ending grid zone.
  • UTM easting.
  • UTM northing.
  • UTM grid azimuth.

k. Program 11--Trig Traverse and Subtense. This program has two separate operations--trig traverse and subtense. Both operations of this program compute horizontal distances. Computations for both operations are recorded on DA Form 5603-R.

l. Program 12--Intersection. This program computes the UTM coordinates of a target by intersection. Computations are recorded on DA Form 5604-R. A maximum of 40 targets can be computed when the same OPs are common to subsequent targets. This program can be used for either type of target area base (intervisible or nonintervisible). The following data are required:

  • Coordinates of OP 1 (01).
  • Coordinates of OP 2 (02).
  • Azimuth from OP 1 to target.
  • Azimuth from OP 2 to target.
  • Vertical angle from OP 1 to target.

m. Program 13--Artillery Astronomic Observation (Arty Astro). This program computes a grid azimuth from three observations of the sun or survey star. Data for either observation is recorded on DA Form 7285-R. This program uses an electronic ephemeris, which eliminates the need to extract data from FM 6-300. The program provides the option of using the internal timer or manually entering the date and time of tip for each observation. The ability to manually input the date and time of observation allows surveyors to perform fieldwork without BUCS being at the site of observation. The program cheeks the accuracy specifications in the same manner as Program 5.

12-7. SPECIAL APPLICATIONS

Several special applications of the BUCS can be performed by the user. These applications are as follows:

  • Using the continuous memory.
  • Exiting and reentering the program mode.
  • Setting the time and date.
  • Making time corrections and adjustments (internal timer).
  • Determining time accuracy requirements.
  • Adjusting the contrast of the display.
  • Increasing the speed of data input and calculations.
  • Clearing the memory.
  • Inserting RUNNING CLOCK program into BUCS memory.

a. Using BUCS Continuous Memory. To protect the BUCS from running down the batteries, a built-in safety feature turns the computer off after 10 minutes of inactivity. The BUCS has a continuous memory which allows the operator to recall the last program and its calculations at any time without loss of survey data.

(1) The operator uses the following steps to recall the last program and its calculations before the computer is turned off:

    Step 1. Turn the computer on.

    Step 2. Press the f key.

    Step 3. Press the CONT key.

    Step 4. Press the END LINE key.

(2) This procedure will recall the program and the calculations. The computer will display the prompt which follows the prompt at which the computer turned itself off. Use the backup procedure to verify the data of the previous display prompt, and continue computations.

b. Exiting and Reentering BUCS Program Mode. The BUCS allows the operator to exit the survey program at any time for the purpose of performing mathematical calculations independent of the program. The operator may reenter the survey program at any time without loss of memory.

(1) The following steps must be performed to exit the program mode and go to the calculation mode:

    Step 1. Press the ON key to clear the display.

    Step 2. Press the f key.

    Step 3. Press the CALC key.

The computer is now in the CALC mode and ready to perform mathematical problems independent from the survey program.

(2) The following steps must be performed to reenter the program mode:

    Step 1. Press the f key.

    Step 2. Press the CALC key.

    Step 3. Press the f key.

    Step 4. Press the CONT key.

    Step 5. Press the END LINE key.

The computer will return to the display prompt which follows the display prompt where the program was exited.

(3) The following steps must be performed to reenter the program mode at the very start of the display prompt ^DATE 01-JAN-00:

    Step 1. Press the f key.

    Step 2. Press the CALC key.

    Step 3. Press the RUN key.

    Step 4. Press the END LINE key.

The computer is now in the program mode and ready to perform survey programs 1 through 13.

Note. The procedure in (3) will discard the program which was run before this procedure.

c. Setting Date and Time (Internal Timer). The BUCS contains an accurate quartz-crystal clock and a calendar covering several thousand years. The clock and calendar are referred to as the internal timer in this chapter. The internal timer is accessed at the TIME MODULE prompt in the program instructions. This internal timer runs whether the BUCS is on or off. It begins as soon as the batteries are installed. The steps for setting the date and time are as follows:

Step 1. Turn BUCS on.

Step 2. Type RUN SURVEY.

  • The SURVEY routine will call a subroutine (DATIME) which will then request the proper date by displaying ^DATE:DD:-MMM-YY. The DD is the day; MMM, the month; and YY the year. The operator can either accept the date that is displayed by pressing the END LINE key or type in a new date in the same format as given in the prompt and then pressing the END LINE key.

  • The subroutine DATIME will next request the proper time of day by displaying TIME:hh:mm:ss. The hh is the hour (24 hour clock); mm the minute; and ss, the second. The operator can either accept the displayed time by pressing the END LINE key or change it by typing in a new one. If the operator decides to change the time given, he must input the entire time, including the seconds.

The example below shows this procedure.

d. Making Time Corrections and Adjustments (Internal Timer). BUCS has a versatile set of statements and functions to set and adjust the quartz-controlled clock and to change its speed. The system clock is regulated by a quartz crystal with a typical accuracy of 1.5 minutes per month. The accuracy of the clock is affected by temperature, physical shock, humidity, and aging. HP71 Owner's Manual (Section 5, page 90) describes how to refine the time keeping accuracy of the clock if required. The time adjustment statements described in Section 5 must be followed exactly. An improper use of these statements could lead to a very inaccurate clock speed.

e. Determining Time Accuracy Requirements. The new astro programs within the SURVEY MODULE REV1 (Star ID, Hasty Astro, and Arty Astro) use the hour-angle formulas to compute azimuth. The new astro programs require the time accuracies shown in Table 12-7.

f. Adjusting the Contrast of Display.

(1) The BUCS allows you to adjust the contrast by controlling the display intensity and optimum viewing angle. You may choose a contrast value from 0 to 15. Contrast 0 gives you the least contrast and shallowest viewing angle. Contrast 15 gives you the sharpest contrast and steepest viewing angle and also makes all the annunciators easily visible. After memory reset, contrast value is set to 9. You can adjust the contrast value to suit your own preference.

(2) To adjust the contrast and the viewing angle, type CONTRAST 15 and press the END LINE key. This will give you the sharpest contrast. Choose your own preference by selecting any number from 0 to 15.

Note. If the contrast is set to 0, the display appears blank unless it is viewed at a low angle. Therefore, when BUCS is turned on with the contrast set to 0, the BUCS may appear to be off. This problem can be remedied by setting the contrast to 8.

g. Increasing Speed of Data Input and Calculations. The BUCS allows the operator to increase the speed of data input and calculations. This feature has the advantage of being able to type in the data without waiting for the next display prompt. The disadvantage is that the operator cannot verify the data until the program is completed. When using this rapid application, the operator must have the program prompts completely memorized.

(1) To activate the rapid application type DELAY 0,0 and press the END LINE key.

(2) To deactivate the rapid application, type DELAY .1,.1 and press the END LINE key.

h. Clearing BUCS Memory. When the SURVEY REV1 module is installed, BUCS has a 64K memory and is able to store many programs of CALC mode and BASIC mode. However, when your unit begins field operation, you should clear the computer memory if it is cluttered with your personal program. Having the computer memory filled with your own programs could result in the BUCS not accepting the survey programs and prompting INSUFFICIENT MEMORY. Should this occur, you must clear and reset the BUCS memory. To clear and reset the BUCS main user memory (also called RAM), the operator must perform the steps discussed below.

    Step 1. Press and release the ON and / keys at the same time.

    Step 2. The display prompts INIT: 1. All the keys are now inactive except 1, 2, 3, and END LINE. To reset the memory, press the 3 and END LINE keys.

    Step 3. The display prompts MEMORY LOST. Clear the display by pressing the ON key.

i. Inserting RUNNING CLOCK Program Into BUCS Memory.

WARNING

This routine may be used only with the BUCS SURVEY REV 1 module. Use with any other module (for example, cannon) is not authorized because of memory restrictions.

(1) The following program can be inserted into the BUCS memory to create a RUNNING CLOCK routine:

    Step 1. Press the ON key.

    Step 2. Type in EDIT CL, and press the END LINE key.

    Step 3. Type in 5 DELAY 0,0, and press the END LINE key.

    Step 4. Type in 10 TIME $, and press the END LINE key.

    Step 5. Type in 20 GOTO 10, and press the END LINE key.

This routine will now remain in your BUCS indefinitely unless BUCS power has been lost for more than 30 seconds. If the program is lost, it can be reinserted again following the procedure in (1) above. If you make a mistake while inserting the program into BUCS memory, press the ON key and start again with step 1.

(2) To check the accuracy of your BUCS clock once the RUNNING CLOCK routine has been inserted into the BUCS memory, perform the following:

    Step 1. Press the ON key.

    Step 2. Type in RUN CL, and press the END LINE key.

BUCS will now display a running clock. The displayed time should be checked against a time signal received via a time signal receiver. BUCS displayed time may be about 1/2 second behind the actual time. This discrepancy is due to the inserted RUNNING CLOCK routine and should not be construed as an error in the time setting. Once the BUCS clock has been viewed long enough to ascertain i fit is correct, press the ON key to stop the clock. If the time is correct, key in RUN SURVEY to start your survey computations. If the time is not accurate enough to compute astro observations (hasty astro or arty astro) by using the BUCS internal clock, key in RUN SURVEY and set the correct time into the BUCS internal clock at step 2 (TlME prompt). To recheck your BUCS clock, press the ON key and perform steps 1 and 2 above.

12-8. MAINTENANCE AND TROUBLESHOOTING

a. Computer and Printer Maintenance. The HP71B computer and HP2225B printer can be cleaned with a soft cloth, dampened either in clean water or in water containing a mild detergent. Do not use an excessively wet cloth or allow water to get inside these components. Do not use abrasive cleaners on the computer display window. The printer battery pack is not user-serviceable.

WARNING

Do not incinerate or mutilate the printer battery pack. The battery pack may release toxic materials or burst under extreme heat. Do not connect together or otherwise short-circuit the battery pack terminals. The battery pack may melt or cause serious burns.

b. Print Head Maintenance. The HP2225B print head cartridge is easy to maintain. Avoid touching the print head face with your fingers. Avoid allowing the print head face to come into prolonged contact with other materials. This may cause the ink to wick out of the print head.

WARNING

The ink in the print head cartridge contains diethylene glycol, which is harmful if swallowed.

c. Troubleshooting. Table 12-8 lists the possible error conditions that may occur on the ThinkJet printer and the corrective action for eliminating the problem.





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