Tool Operating Manual (9U-7400 Multitach II Group, 9U-7401 Multitach II, 9U-7402 Multitach Photo Group){0781} Caterpillar

Introduction

Illustration 1.

The 9U-7401 Multitach II is a hand-held battery operated, dual channel digital tachometer. It replaces the former 6V-2100 Multitach with a much more versatile unit. Multitach II is actually three instruments in one, a Programmable Tachometer, an Engine Set Point Indicator, and a Frequency Meter. The following features are included in Multitach II:

* Rechargeable, battery-operated.

* Two digital displays show Input 1 and Input 2 values simultaneously.

* Engine set point indicator captures and displays set point RPM.

* Hz frequency meter measures gen set or other signal frequency.

* Non-volatile memory allows storage of all values on display.

* Displays minimum, maximum, and difference values of inputs.

* Displays difference between Input 1 and Input 2.

* Display backlight for operation in low-light conditions.

* Optional RS232 output available for printing directly to printer.

Multitach II accepts many different types of pickups including most pickups used with the former Multitach II. Each input can be programmed separately with different PPR (Pulses Per Revolution) values for each input. Also, a different type of pickup can be used on each input at the same time. Operation is easy because Multitach II always stays preprogrammed for the values it was last used with. It is ready to display values when turned ON.

Contents of 9U-7400 Multitach II Group

Illustration 2. Contents Of 9U-7400 Multitach II Group. Refer to Chart A.

Contents of 9U-7402 Multitach II Photo Group

Illustration 3. Contents Of 9U-7402 Multitach II Photo Group. Refer to Chart B.

Optional Items Used With 9U-7401 Multitach II

Illustration 4. Optional Items. Refer To Chart C.

NOTE: Five batteries are required to power Multitach II.

Specifications for 9U-7401 Multitach II

Refer to NOTICE statement before using alkaline batteries.

Use the following graph to determine accuracy for any PPR and RPM combination. Use smallest PPR number possible for highest accuracy.

Illustration 5. RPM Accuracy Chart.

Description of Multitach II Digital Display

Illustration 6. Digital Display.

1. INPUT 1 DIGITAL DISPLAY: Displays the values for Input 1 functions.

2. MAX and MAX - MIN Indicator: MAX only will show when the maximum value is being shown. MAX - MIN will show when the difference value (maximum value minus minimum value) is on the display.

3. INPUT 1: Indicates this upper display shows Input 1 values, also flashes after INPUT 1 key has been pressed to indicate that all keys will work for Input 1 when flashing.

4. LO BAT: Shows on display only when the internal NiCad Batteries need recharging. See the "Charging the Internal Nickel Cadmium Batteries" section in this manual, to check battery Voltage.

5. OVERRUN: When SET POINT function is in use, OVERRUN indicates the engine rack contact is less than 10% closed.

6. SETPOINT: Indicates the SET POINT function has been selected.

7. LUG: When SET POINT function is in use, LUG indicates the engine rack contact is over 75% closed.

8. MEMORY: Indicates the value on the display is the value stored in the memory which has been selected.

9. RPM: Indicates the value on the display is Revolutions Per Minute.

10. PPR: Indicates the value on the display is the Pulses Per Revolution setting which will be used to calculate RPM. The PPR number always flashes on the display as an additional indication.

11. NO INPUT: When NO INPUT shows on the display, no input is connected to the corresponding input or the amplitude of the signal is not large enough to be detected.

12. HZ: Indicates the value on the display is Hz (cycles per second) frequency measurement.

13. Decimal Point: The decimal point is automatically placed when measuring Hz. It can also be selected in the PPR mode to represent tenths of Pulses Per Revolution.

14. Digital Display: These digits are used to display the value being measured.

15. Minus Sign: When displaying the INPUT 1 - INPUT 2 value it is always shown on the lower display, and it is possible to have a negative value which will be indicated by this minus sign.

16. INPUT 1 - INPUT 2: Indicates when the value on the display is INPUT 1 - INPUT 2. Also, INPUT 2 alone will be ON and flashing after the INPUT 2 key is pressed to indicate Input 2 has been selected and the keys will work for Input 2.

Description of Keys and Front Panel on Multitach II

Illustration 7. Description Of Multitach II Keys and Front Panel.

Color Code of Keys on Front Panel:

Blue: Identifies Function Keys: RPM, SET POINT, HZ, MEM VALUE, and SAVE.

Red: Identifies the PPR Key and the number keys (the keys below the red numbers) which change the PPR value.

1. SET POINT: Selects the SET POINT display for INPUT 1 or INPUT 2, whichever is flashing. OVERRUN or LUG will be shown on the display depending on the status of the engine rack contact. The display will also show the RPM of the input signal if an RPM pickup is connected to the INPUT. The SAVE key can be pressed when in the SET POINT mode and MEMORY on the display will flash until the set point is reached, then the SET POINT value will be stored in memory and the SET POINT RPM will be displayed. Pressing CLEAR will clear the memory so it is ready for another SET POINT value. Subtract 20 RPM from the set point value to obtain engine full load RPM.

2. RPM: (Revolutions Per Minute): Press to read the RPM for the input signal connected to INPUT 1 or INPUT 2, whichever is flashing on the display. The RPM value shown will be based on the PPR value in memory.

3. Hz (Hertz) and 3: Displays the frequency of the input signal connected to INPUT 1 or INPUT 2, whichever is flashing on the display. The decimal point will automatically be placed in the proper location. This key is also used to enter the number 3 when in the PPR mode.

4. PPR (Pulses Per Revolution): Displays the PPR value of INPUT 1 or INPUT 2, whichever is flashing on the display. When shown on the display the value will be flashing and can be changed at any time by pressing CLEAR and using the red number keys to enter the desired number.

5. MEM VALUE (Memory Value): Shows the value stored in memory for the function in use for INPUT 1 or INPUT 2, whichever is flashing. This key is also used to enter the number 6 when in the PPR mode.

6. CLEAR: Clears the MEMORY value or PPR value only when shown on the display for INPUT 1 or INPUT 2, whichever is flashing. If SET POINT is on the display, pressing CLEAR will clear and reset the SET POINT memory and cause MEMORY to flash on the display. This will allow the RPM value to be shown until SET POINT is reached and then the SET POINT RPM will be stored in MEMORY and displayed.

7. IN 2 (Input 2): Allows INPUT 2 (lower half of the display) functions to be changed with the front panel keys. When pressed, INPUT 2 will flash on the display to indicate it has been selected. This key is also used to enter the number 9 when in the PPR mode.

8. ON/OFF: Turns the Multitach II ON or OFF. The Multitach II will automatically turn OFF after 5 minutes, if not in use. This feature can be disabled. See the "Multitach II Auto Turnoff Feature" section in this manual, for additional information.

9. IN 1 (Input 1): Allows INPUT 1 (upper half of the display) functions to be changed with the front panel keys. When pressed, INPUT 1 will flash on the display to indicate that it has been selected. This key is also used to enter the number 8 when in the PPR mode.

10. Turns the display backlight ON for viewing in low-light conditions. The backlight will automatically turn OFF after 5 minutes. It can also be set to stay ON as long as the Multitach II is ON. Refer to "Display (LCD) Backlight Auto Turnoff Feature" section in this manual, for additional information. This key is also used to enter the number 7 when in the PPR mode.

11. SAVE: Press to save the displayed value for INPUT 1 or INPUT 2, whichever is flashing on the display. MEMORY will flash on the display until the value is saved. This saved value can be viewed at any time by pressing MEM VALUE. This key is also used to enter the number 5 when in the PPR mode.

12. PRINT: If the RS232 option has been installed in Multitach II, and the RS232 connector is connected to a printer, pressing this key will cause all values on the display and in memory to be printed. This key is also used to enter the number 4 when in the PPR mode.

13. IN1 - IN2 (Input 1 minus Input 2): Displays the difference value of INPUT 2 subtracted from INPUT 1. This value is always shown on the lower display. This key is also used to enter the number 2 when in the PPR mode.

14. MAX - MIN (Maximum - Minimum): Displays the difference value between the maximum and minimum values being measured or in MEMORY, whichever is on the display when MAX - MIN is pressed. Works for INPUT 1 or INPUT 2, whichever is flashing. This key is also used to enter the number 1 when in the PPR mode.

15. MAX (Maximum): Displays the maximum value measured for INPUT 1 or INPUT 2, whichever is flashing on the display. This value can be set to zero by pressing CLEAR when MAX is displayed. It will immediately start recording a new maximum value after clearing. This key is also used to enter the number 0 when in the PPR mode.

16. MIN (Minimum): Displays the minimum value measured for INPUT 1 or INPUT 2, whichever is flashing on the display. This value will always be zero unless CLEAR is pressed after a value is on the display. This key is also used to enter the decimal point when in the PPR mode.

17. CHG (Charge): Identifies the connector located on the top panel for the 4C-3024 Battery Charger.

18. IN 1 (Input 1): Identifies the setpoint input connector which displays RPM or Hz on the upper (INPUT 1) digital display.

19. IN 2 (Input 2): Identifies the setpoint input connector which displays RPM or Hz on the lower (INPUT 2) digital display.

20. IN 1 (Input 1): Identifies the input connector which displays the RPM or Hz on the upper (INPUT 1) digital display.

21. IN 2 (Input 2): Identifies the input connector which displays the RPM or Hz on the lower (INPUT 2) digital display.

Settings and Displays Available from Front Panel (Not Labeled)

The following displays and internal settings for Multitach II can be shown and changed from the front panel touch switch by pressing the keys as described below. Pressing any other key will go back to normal operation.

Displaying Battery Voltage

With Multitach II ON or OFF, press and hold the CLEAR key and press and release the ON/OFF key. The display will show the internal battery voltage, to check the charge in the batteries or to check if the batteries are being charged. The display is as shown:

Batteries Fully Charged:

Batteries Discharged (LO BAT):

Multitach II Auto-Turnoff Feature

To set or check the 15 minute auto-turnoff feature, with Multitach II OFF, press and hold the PPR key, then press and release ON/OFF. To change the setting, press the PPR key again. When the Auto-Turnoff feature is OFF, Multitach will stay ON until the ON/OFF key is pressed. The display is as shown:

Auto-Turnoff working:

Auto-Turnoff not working:

Display (LCD) Backlight Auto-Turnoff Feature

The display backlight can be set to turn ON only when the key is pressed and automatically go OFF after 5 minutes (Lcd LitE oFF), or it can be set to always automatically go ON whenever Multitach II is in use (Lcd LitE on). To set or check this feature, with Multitach II OFF, press and hold the "light bulb" key (10, Illustration 7) down, then press and release ON/OFF. To change the setting, press the "light bulb" key again. The display is as shown:

Display backlight turns ON with key and OFF after 5 minutes:

Display backlight will always be ON whenever Multitach II is ON:

Printer Baud Rate Setting

To display or change the baud rate used with the optional RS232 port, with Multitach II OFF, press and hold the MAX-MIN key, then press and release ON/OFF. To change the setting, press the MAX-MIN key again. Every time the MAX-MIN key is pressed, the baud rate will change to one of the four possible choices. When the desired baud rate is on the display, press any key other than MAX-MIN to exit this display, and the setting will automatically be saved. The display is as shown:

Printer Control Settings

A printer connected to the optional RS232 port can be made to print only once whenever the PRINT key is pressed, or print continuously every 10 seconds until PRINT is pressed a second time. To display or change this setting, with Multitach II OFF, press and hold the PRINT key, then press and release ON/OFF. To change the setting, press the PRINT key again. The display is as shown:

Printer will print only once after PRINT key is pressed.

Printer will print every 10 seconds after pressing PRINT until PRINT is pressed again.

Displaying the Software Version

To display the version number of the software being used in the program module in the Multitach II, with Multitach II OFF, press and hold the MIN key, and press and release ON/OFF. The version number can only be changed by replacing the program module. The display is as shown:

Connections to the 9U-7401 Multitach II

Illustration 8. 9U-7401 Connectors. (1) Charge Connector. (2) Connections for 8T-5111 Adapter Cable and 1P-7446 Rack Cable. (3) Connections for speed pickups or frequency (Hz) input. (4) Location of optional RS232 output connector for printer output.

1. CHG (Charge) Connector. Used to connect the 4C-3024 Battery Charger when recharging the internal NiCad Batteries.

This connector can also be used to power the Multitach II with the 4C-3024 Battery Charger or cigarette lighter adapter. Refer to "Charging the Internal Nickel Cadmium Batteries" section in this manual, for charging instructions.

2. SET POINT INPUT 1 and SET POINT INPUT 2: Connection for 8T-5111 Adapter Cable and 1P-7446 Rack Cable. The clips on the end of the rack cable clip connect to the rack contact on Caterpillar Engine governors.

3. RPM and Hz INPUT 1, RPM and Hz INPUT 2: Connection for speed pickups or frequency (Hz) input.

NOTE: The 9U-7505 High-Voltage Adapter must be used for Voltages over 60 Volts.

4. RS232 OUTPUT LOCATION: Location of optional RS232 output connector for printer output. This connector may be added to any 9U-7401 Multitach by ordering the 4C-9499 RS232 Adapter Group.

Charging the Internal Nickel Cadmium Batteries

The Multitach II is provided with rechargeable NiCad (Nickel Cadmium) batteries installed and a 4C-3024 Battery Charger (2). Before using the Multitach II, these batteries must be charged.

Illustration 9. Rear View Of 4C-3024 Battery Charger. (1) Switch. (2) Power Supply. (3) Charger Connector. (4) AC Line Voltage.

Procedure

1. Move switch (1) on the rear of 4C-3024 Battery Charger (2) to the correct AC line Voltage, either 120 Volts or 230 Volts depending on use.

2. Insert charger connector (3) into the CHARGE connector on the top of the Multitach II.

3. Plug power supply end (4) into an AC outlet.

NOTE: For operation outside the U.S.A., an AC power plug adapter may be required.

4. Turn the Multitach II ON to check if the batteries are being charged. This will be indicated when LO BAT on the display disappears. It may be necessary to wait a few minutes until the batteries are sufficiently charged to operate the Multitach II. You can also check the internal battery Voltage using the instructions in the "Setting and Displays Available from Front Panel (Not Labeled)" section in this manual, to make sure the voltage increases, indicating charging is taking place.

5. When first turned ON, the display may flash, indicating low voltage. The flashing should stop after a few minutes as the batteries are charged.

6. Turn the Multitach II OFF and leave the charger on for 10 to 12 hours.

NOTE: The Multitach II will not be damaged if the charger is left on for longer time periods. For maximum battery life, recharge the batteries only after the LO BAT indicator shows on the display or the battery Voltage is less than 5.2 Volts (5.2bAtt).

Replacing the Internal NiCad (Rechargeable) Batteries

The 9U-7401 Multitach II is provided with five 1U-7445 NiCad (Nickel Cadmium), Rechargeable AA Batteries. These can be replaced with new 1U-7445 Batteries when they no longer give sufficient operating time, or they can be replaced with 1U-9533 Alkaline (non-rechargeable) Batteries.

NOTE: The internal batteries can be removed indefinitely and the internal memory values will not be affected.

Illustration 11. Back View Of Multitach II. (1) Screws (two). (2) Battery Cover.

1. Loosen two screws (1) from battery cover (2). Screws are designed to remain attached to battery cover, even when it is removed.

2. Remove battery cover (2).

Illustration 12. Multitach II With Battery Cover Removed. (3) Batteries.

3. Remove all batteries (3) and replace with new batteries.

4. To install new batteries: The + terminal of the battery must be placed on the battery contact with the (+) symbol (4) (in the recessed area of the battery compartment, as shown in Illustrations 13 and 14).

Illustration 13. Multitach II With Batteries Removed. (4) "+" or positive terminal.

Illustration 14. Enlarged View Of Battery Compartment. (4) "+" or positive terminal.

The easiest way to install the batteries is to place the (-) terminal of one battery against one of the negative battery contacts inside of the battery compartment (5). Compress the negative battery contact as much as possible (see Illustration 15) and then install the plus terminal (+) of the battery into the battery compartment.

Illustration 15. Installing Battery. (5) Battery (-) negative terminal. (6) Battery (+) positive terminal.

5. install battery cover (2) and replace two screws (1).

Care and Cleaning of the 9U-7401 Multitach II

The 9U-7401 Multitach II is a durable hand-held instrument. However, since it will be used outdoors in a wide range of conditions, care must be taken to protect it and keep it clean. The case is water-resistant, but not waterproof and the indicator can be damaged if water is allowed to enter the case. If moisture does enter the case, the indicator should be allowed to dry out. Remove the rear cover and allow it to dry completely in a warm dry area. Keep the Multitach II in the carrying case when not in use, or use the 9U-5215 Soft Tool Case to protect the Multitach ii.

Operating Instructions for Multitach II

General Operating Instructions

To turn the Multitach II ON: Press and release the ON/OFF key. Pressing it a second time will turn it OFF. When the Multitach II first comes ON, all segments will show on the display as a check to show the display is working properly. The display should appear as shown in Illustration 16 and will only be shown for a few seconds. Also the display backlight will turn ON then OFF as a test.

Illustration 16. Liquid Crystal Display With All Segments On.

When the Multitach II is turned ON, the functions will be set to the previously used settings. Follow this procedure to change the settings.

1. Determine which input, INPUT 1 or INPUT 2 will be used first. INPUT 1 is the top display, and INPUT 2 is the bottom display. Press IN 1 or IN 2 to indicate your choice. INPUT 1 or INPUT 2 will flash on the display to indicate your choice. All the keys will work for whichever input is flashing. To change the keys to work for the other input, press the other IN key.

2. Select the function you plan to use by pressing either the RPM, SET POINT, or HZ key. The function label should be shown on the display after the key is pressed. After selecting one of these functions, select MEM VALUE, if desired, to show the value that was recorded in memory earlier, or press SAVE to enter any value shown on the display into memory. This value will be saved even when Multitach II is turned OFF.

3. The MIN, MAX, MAX-MIN, and IN 1 - IN 2 keys can be pressed at any time to show the calculated values for the INPUT that is flashing on the display. The following is a explanation of each.

MIN (Minimum): Shows the minimum value that was measured since Multitach II was turned ON or since the CLEAR key was pressed when MIN is on the display. To record the minimum engine speed during a test, first read the RPM of the engine on the display, then press MIN, and then CLEAR to reset this memory to normal engine speed. Go back to RPM and the MIN memory will automatically be updated if the RPM drops below the value in the MIN memory. The MIN memory will always be reset to zero when the Multitach II is turned OFF.

MAX (Maximum): Shows the maximum value that was measured since Multitach II was turned ON or since the CLEAR key was pressed when MIN is on the display.

MAX-MIN: Shows the difference value between the maximum and minimum values being measured or in MEMORY, whichever is on the display.

IN 1 - IN 2: (Input 1 - Input 2): Shows the difference value of INPUT 2 subtracted from INPUT 1. This value is always shown on the lower display.

OVERRANGE INDICATOR: - - - - (Four dashes on display): Indicates the RPM or frequency of the input signal is greater than the specifications of Multitach II.

Using the 9U-5140 Photo Pickup to Read RPM

NOTE: No visible light will be seen coming from the glass end of the 9U-5140 Photo Pickup. It uses infrared light which is not visible to the human eye.

1. Clean an area on the outside of the part whose rotation is being measured. This should be directly in front of where the photo pickup will be installed. Cut a piece of retro-reflective tape approximately 20 mm (.75 in) long. Remove the protective backing and press the tape on the clean area of the part.

NOTE: Usually one piece of tape is enough, but more may be used if desired. If more than one piece is used, put the pieces at least one tape width apart.

Illustration 17. Setup For The Photo Pickup. (1) Extension Cable. (2) Photo Pickup. (3) Thumbscrew. (4) Magnetic Base. (5) Base and Sight.

2. Setup the photo pickup.

a. Connect the 6V-2198 Extension Cable (1) to RPM and HZ INPUT 1 or 2 of Multitach II.

b. Connect the 9U-5140 Photo Pickup (2) to the other end of the cable.

c. Loosen thumbscrew (3) on 6V-3137 Magnetic Base (4), and install pickup (2).

d. Tighten thumbscrew (3).

3. Position the photo pickup.

a. Put the magnetic base on a metal surface so the front of the photo pickup will not be closer than 76 mm (3 in), or more than 762 mm (30 in) away from the reflective tape. Use the 6V-3138 Extension Rod if required.

b. Turn the Multitach II ON.

c. Loosen thumbscrew (5) on the base and sight straight down the side of it towards the reflective tape. When the pickup is properly aligned, the red light at the rear of the pickup will be ON.

d. Tighten the thumbscrew on the base. Final adjustment can be made after the engine is running.

NOTE: If the red light on the rear of the pickup does not go out when the pickup is moved away from the tape, it is too close to the surface the tape is on. Also, it is sometimes necessary to aim the photo pickup at an angle towards the tape rather than straight at it.

4. Read the speed.

a. First press IN 1 or IN 2, to select whichever input has the Photo Pickup connected to it.

b. Press the PPR key to make sure the PPR number is correct. For the photo pickup the PPR number should be equal to the number of pieces of tape on the rotating part which is usually 1. If the number is incorrect, you can change it by pressing the red number keys. When the PPR value is flashing on the display and you press any of the red number keys, the old PPR value will be erased and the new number will be entered. The number entered must show on the display and flash ON and OFF. This flashing display always identifies the PPR number display.

5. Press RPM to read the speed of the rotating part. If the display is not stable, make sure the NO INPUT indicator on the display is not ON. If it is, readjust the photo pickup until it stays OFF. Also, the red light on the rear of the photo pickup must be ON (constant) when the part is rotating.

Using the 5P-7360 Tachometer Generator or Magnetic Pickups

Multitach II can measure RPM of a rotating part by using almost any type of magnetic pickup or generator. The only requirement is that the output signal be within the specifications of Multitach II. Multitach II will count the number of pulses and display the RPM if the correct PPR (Pulses Per Revolution) number is being used. Following are directions for using the Tachometer Generator and some of the more common magnetic pickups.

Using the 5P-7360 Tachometer Generator

Illustration 18. 5P-7360 Tachometer Generator.

1. The 5P-7360 Tachometer Generator can be used on engines equipped with a tachometer drive. It contains an internal 20 tooth gear and has a magnetic pickup to sense the gear teeth. To use the tachometer generator, remove the engine's Service Meter if it has one, and install the 5P-1759 Tachometer Drive Group (1) and 5P-7360 Tachometer Generator (2). Connect the 9U-7506 Magnetic Adapter Cable to the Tachometer Generator cable. Use the 6V-2198 Extension Cable to connect to RPM and HZ, IN 1 or IN 2.

2. To read the speed, first select IN 1 or IN 2, then press the PPR key to check if this value is correct. If the tachometer generator is mounted on the engine's tachometer drive, the PPR number is 10 (tachometer drive runs at one-half engine speed). On applications where the tachometer generator is directly driven, the PPR is 20. If the PPR number flashing on the display is incorrect, change it to the correct value by pressing the red number keys.

3. Press RPM to read the speed of the rotating part.

Using the Magnetic Pickup

8L-4171 Magnetic Pickup (Optional):

Illustration 19. 8L 4171 Magnetic Pickup. (1) Flywheel Housing. (2) 8L-4171 Magnetic Pickup. (3) Magnetic Pickup Installed.

The 8L-4171 Magnetic Pickup (2) is just one of many magnetic pickups which can be used with Multitach II to read speed. Many Caterpillar engines already have magnetic pickups installed which can be used for an input signal. These magnetic pickups provide an output pulse which can be counted by the multitach whenever the sensing tip of the pickup is within approximately 3.2 mm (1/8 in) of a rotating ferrous metal part. Therefore, these pickups can be used to sense the gear teeth on an engine flywheel to obtain engine RPM. Some Caterpillar engines are equipped with a threaded hole in the flywheel housing (1) which will accept this pickup, as shown in Illustration 19.

1. In engines with a threaded hole in the flywheel housing, remove the plug and install the pickup. If no hole is present, a hole must be drilled and tapped directly in line with the center of the flywheel teeth. Turn the pickup clockwise into the hole until it just comes in contact with the teeth of the flywheel. Turn the pickup counterclockwise one complete turn, and tighten the locknut.

2. Use the proper adapter cable to connect the pickup to the 6V-2198 EXTENSION Cable. A 6V-4156 Adapter Cable and a 9U-7506 Magnetic Adapter Cable are needed to connect the 8L-4171 Magnetic Pickup to the 6V-2198 Extension Cable. Connect the extension cable to RPM and HZ, IN 1 or IN 2.

3. To read the speed, first select IN 1 or IN 2, then press the PPR key to enter the proper PPR number. If the pickup is sensing the teeth on a flywheel or other gear, the PPR number will be the number of teeth on the gear. For flywheels this number can be found in the engine parts book. For sensing moving parts other than gear teeth, the PPR is the number of metal objects that will pass within sensing distance of the pickup tip during one rotation of the part being measured. Press the red number keys to enter the new PPR number while the display is flashing.

4. Press RPM to read the speed of the rotating part. If the reading is not stable, readjustment of the pickup may be required. When the proper signal is being received, the NO INPUT indicator on the display should stay OFF.

Using TDC (Top Dead Center) Magnetic Pickups (Optional):

Illustration 20. (1) Transducer Adapter. (2) Magnetic Pickup. (3) Flywheel Housing.

Illustration 21. (1) 8T-5184 Magnetic Pickup, 89 mm (3.5 in) long. 6V-2197 Magnetic Pickup, 114 mm (4.5 in) long 8T-5185 Magnetic Pickup, 178 mm (7.0 in) long. (2) 6V-2199 Transducer Adapter, 1/8" NPTF. (3) 6V-3093 Transducer Adapter, 1/4" NPTF.

These small 6.4 mm (.25 in) diameter pickups are available for installing in the static timing hole on Caterpillar Engines to sense the Top Dead Center hole in the flywheel. When the pickup is adjusted correctly, it will sense the static timing hole in the face of the flywheel, and generate one output pulse whenever the timing hole passes by the pickup. Because this will produce one pulse per revolution of the crankshaft, the PPR number for this application is 1.

1. To use one of these magnetic pickups, find the static timing hole. If necessary, refer to the Service Manual to find this location. Remove the plug from the hole. Depending on the size of the static timing hole, install either a 6V-2199 or 6V-3093 Transducer Adapter on the magnetic pickup. Put the pickup into the timing hole, and screw in the transducer adapter. Tighten the nut nearest to the engine with a wrench, but leave the locknut loose. Push in the pickup until it just comes in contact with the face of the flywheel; then pull out the pickup 1.6 mm (16 in) and tighten the locknut finger tight.

2. Connect the output lead of the pickup to the 9U-7506 Magnetic Adapter Cable. Connect the other end of the adapter cable to the 6V-2198 Extension Cable. Connect this cable to Multitach II RPM and HZ, IN 1 or IN 2.

3. Set the PPR to 1 on Multitach II, then press RPM to read the speed. If the reading is not stable, the pickup may need to be readjusted.

Using the Injection Line Pickup (Optional)

The injection line pickup provides a method of sensing engine speed through the fuel injection lines on non-unit injected engines with external fuel injection pumps. This method provides fast easy installation of an RPM pickup without any engine disassembly.

Two different injection line speed pickup groups are available the 6V-4950 Group and the 4C-6821 Group. Both will work with Multitach II. The amplifier in the 4C-6821 Group has a switch to allow it to be used with the 4C-6800 Data Logger. Both groups use the same 1U-9139 Universal Pickup which will fit fuel injection lines from 5.5 mm (.216 in) to 7.0 mm (.28 in) diameter. The previous older 6V-6114 Pickup will fit only 6.5 mm (.25 in) lines.

Illustration 22. 6V-4950 Injection Line Group. (1) 1U-9139 Pickup. (2) 6V-6113 Amplifier. Not Shown: Refer to SEHS8029 Special Instruction.

Illustration 23. 4G-6821 Injection Line Group. (1) 1U-9139 Pickup. (2) 4C-6812 Amplifier. Not shown: Refer to SEHS9363 Special Instruction.

Complete installation and operating instructions are provided with the Injection Line Groups. Refer to these for additional instructions.

1. The injection line pickup should be installed on a straight section of fuel injection line. The paint under the area where the pickup is to be installed should be removed.

Show/hide table

All bare metal locations on the fuel lines must be repainted after removal of the pickup group and before the engine is put back in service. If this is not done, the bare metal fuel injection lines can corrode. This could result in a fire if fuel is sprayed on hot engine parts, causing possible personal injury.

Illustration 24. Installing An Injection Line Pickup. (1) Thumbscrew. (2) Pickup. (3) Ground Clip.

2. Loosen thumbscrew (1) on the pickup to open pickup (2). Install the pickup on the line. Tighten the thumbscrew finger tight. Do not use any tools to tighten the thumbscrew. If the output wire is disconnected from the pickup, reconnect it by sliding the lug on the wire under the rivet head with the spring on it. Connect ground clip (3) to bare metal on the engine and connect the output wire to the amplifier. Connect the amplifier output cable to the Multitach II RPM and HZ INPUT. Use the 6V-2198 Extension Cable, if necessary. If the amplifier has a switch on it, set it to the INJ LINE position. Start the engine.

3. Select RPM on Multitach II, and set the PPR at 0.5. Read engine speed on the Multitach II display. Refer to the appropriate Special Instruction on the pickups for troubleshooting operational problems.

Using the Injection Line Pickup on Spark Ignited Engines

While the 9U-5140 Photo Pickup can be used to measure the speed of any spark ignited engine, an alternate method is to use the 6V-4950 or 4C-6821 Injection Line Speed Pickup Group on an insulated spark plug wire. This provides another method to pick up RPM on these engines. However, it may not work properly with some ignition systems. To use this method, follow these instructions:

1. Connect the 1U-9139 Injection Line Pickup to the 6V-6113 or 4C-6812 Amplifier. If the 4C-6812 Data Logger Amplifier is being used, place the selector switch in the INJ LINE position. Connect the cable to a Multitach II RPM and HZ input.

Illustration 25. Injection Line Pickup. (1) Pickup. (2) Insulated Spark Plug Wire. (3) Amplifier. (4) Ground Clip.

2. Place the injection line pickup around the insulation on a spark plug wire back approximately 50 mm (2 in) from the spark plug insulator. Close the pickup and tighten the thumbscrew. Connect the ground clip to bare metal on the engine. Start the engine.

3. Set Multitach II to read RPM and set the PPR to 0.5. The RPM of the engine should be on the display. If the reading is unstable, it may be due to the nature of the ignition system on the engine and this method cannot be used. If this happens, try using the coil output wire going to the distributor instead of a spark plug wire. If the injection line pickup is used on the coil output wire the PPR value should be set at a number equal to one half the number of engine cylinders. For instance, if the engine is a 6 cylinder engine, set the PPR at 3.

4. If stable readings cannot be obtained, use the photo pickup to measure the RPM of the engine.

Using Multitach II to Measure Engine Set Point

Multitach II contains an engine set point feature that can be used for measurements of the set point RPM of Caterpillar diesel engines which have a rack contact on the governor. The set point (formerly called the balance point) is 20 RPM more than the full load RPM of the engine. Because of this, 20 RPM must always be subtracted from the measured set point to find full load RPM. This measurement was formerly measured using the 6V-4060 Engine Set Point Indicator and 6V-2100 Multitach. Only a brief description of set point operation will be given here. For a detailed description of measuring engine set point and a full explanation of set point, balance point, and full load RPM, refer to the SEHS7931 Special Instruction for the 6V-4060 Engine Set Point Indicator.

Illustration 26. Indicators On The Engine Set Point Display.

1. OVERRUN - Indicates engine rack contact is 0 to 10% closed.

2. SETPOINT - Shows whenever set point function is being used (does not indicate the set point has been reached). Set point is at 11% rack contact, or at the point that the OVERRUN indicator turns OFF as engine is very slowly loaded.

3. LUG - Indicates engine rack contact is 75 to 100% closed.

4. MEMORY - When SAVE is pressed in the SETPOINT mode, MEMORY will flash until setpoint is reached then be ON steady and set point RPM will be displayed.

5. RPM - Indicates that RPM is being displayed.

The OVERRUN and LUG indicators on the display are controlled by the microprocessor, and are used to accurately locate the set point of the engine. When the SET POINT INPUT is connected to the engine rack contact, the OVERRUN and LUG indicators show where the engine is operating on the load curve. The OVERRUN indicator is on when the engine is not fully loaded and rack contact is open or is making contact less than 10% of the time.

When the engine is fully loaded and the rack contact is closed or is making contact for more than 75% of the time, LUG will be on. The set point of the engine is when the rack contact is at 11%, or just when the OVERRUN indicator goes out. At set point, the RPM reading on the display will be stored if the SAVE key was pressed before loading the engine.

Procedure for Measuring Set Point

Illustration 27. (1) Rack Adapter Cable. (2) Rack Contact Cable.

Illustration 28. Connecting To The Engine. (3) Insulated Clip. (4) Rack Contact Screw. (5) Metal Clip.

1. Plug the 8T-5111 Rack Adapter Cable (1) into SET POINT INPUTS, IN 1 or IN 2. Plug the 1P-7446 Rack Contact Cable (2) into this adapter. Connect insulated clip (3) of the rack contact cable to rack contact screw (4). Connect bare metal clip (5) of the cable to a bare metal ground on the engine. Connect a speed pickup to the engine and Multitach II as described in the previous section on reading RPM.

IMPORTANT: When using the set point function, there must be no other wires connected to the rack contact screw except rack contact cable clip (3). The rack contact screw is an insulated screw located on the governor housing of the engine. Refer to the Engine Maintenance Manual for the location of this screw. The rack contact screw may have a cap on it. If it does, remove the cap. If necessary, remove any paint from the screw so the bare metal is exposed.

2. Start the engine and let it run until it is at normal operating temperature. Monitor the RPM of the engine at high idle using Multitach II as described in the previous section on RPM measurement to be sure it is correctly indicating the engine speed.

3. Press the SET POINT key and the Multitach II should continue to show the correct engine RPM. Run the engine at high idle. With no load (or a very small load) on the engine, OVERRUN should be on for IN 1 or IN 2, whichever is being used. Keep the engine against the high idle stop for all set point measurements.

Checking and saving the set point RPM: This is the most accurate method of measuring the set point with Multitach II. When SETPOINT shows on the display, press SAVE. MEMORY will start flashing on the display, indicating Multitach II is ready to save a set point RPM. Smoothly increase the load on the engine until OVERRUN goes OFF and MEMORY stops flashing. If OVERRUN goes OFF, but MEMORY does not stop flashing, you have gone through the set point too fast for Multitach II to save the value. If this happens, decrease the load until OVERRUN comes ON then try again, loading the engine very slowly. If the engine load is not held almost constant at the set point for a long enough time it will not save the value, or the value may be incorrect. When MEMORY stops flashing and is ON steady, the value on the display will be the set point RPM.

Checking set point without saving the value: Smoothly increase the load on the engine until OVERRUN goes OFF. Read the RPM at this point. This is the set point. If LUG comes on, you have left the set point and too much load has been applied to the engine. This is not a very accurate method of measuring set point, but may be useful for determining how to load the engine properly.

For various methods of applying loads to different engine applications, see SEHS7931 Special Instruction "Using the 6V-4060 Engine Set Point Indicator Group".

4. The value on MULTITACH II is the set point RPM. To find the full load speed, subtract 20 RPM from the set point RPM reading.

5. After MEMORY is ON steady and the set point RPM is being displayed, press CLEAR to show the actual engine RPM again. To take another set point measurement, press SAVE and load the engine again.

6. At any time, MEM VALUE can be pressed and the last measured set point RPM will be shown.

7. For maximum accuracy, the set point of the engine should be measured a minimum of five times to determine an average reading. Due to fluctuations in load and speed, there will be some difference between the readings. To find the average set point RPM, add the RPM readings together and divide the total by the number of readings taken. Subtract 20 RPM from the average reading to find full load RPM setting of the engine. An example of determining average set point RPM follows.

Set Point RPM reading No. 1 = 2020

Set Point RPM reading No. 2 = 2015

Set Point RPM reading No. 3 = 2025

Set Point RPM reading No. 4 = 2022

Set Point RPM reading No. 5 = 2018

10,100 Total of all RPM readings

Measuring Frequency (HZ) with Multitach II

Multitach II contains a frequency measurement function that is useful for determining the frequency of the input signal connected to the RPM and HZ INPUTS, INPUTS, IN 1 or IN 2. This allows measurement of magnetic pickup signals to check for correct frequency or measurement of AC power and generator set output for proper frequency. Four different signal input methods are described here in Chart E. Direct Voltage input, High Voltage input using the high voltage adapter, using 6V-4960 AC Current Probe use, and using 9U-5795 AC/DC Current Probe.

General Frequency Measurement Instructions

1. Connect the signal to be measured to RPM and HZ INPUTS, IN 1 or IN 2. It can be connected directly if it is below 60 Volts. For Voltages above 60 Volts, use the high voltage adapter or one of the current probes listed above. The high voltage adapter can also be used for lower Voltages to provide clip lead inputs. For direct connection, use an existing cable if available, or use the following diagram to make a cable to connect the signal to the correct input pins of the input.

Illustration 29.

2. To measure the frequency, turn the Multitach II ON, then press IN 1 or IN 2 whichever input the signal is connected to. Press HZ to read the frequency directly in Hz. Frequency up to 1000 Hz is shown with 1 Hz resolution. Frequency over 1000 Hz will have 1 Hz resolution. The PPR is automatically set to read frequency when in Hz and cannot be changed. If the PPR key is pressed when in the HZ mode you must press RPM or SET POINT to get out of the PPR mode. Then press HZ to measure frequency.

Using the 9U-7505 High Voltage Adapter to Measure Frequency

Illustration 30. (1) Cable. (2) Test Leads.

Connect the cable coming from the 9U-7505 High Voltage Adapter (1) to the RPM and HZ INPUTS, IN 1 or IN 2. The 6V-2198 EXTENSION Cable can be used if desired. Insert the 6V-7072 Test Leads (2) into the red and black input jacks in the high voltage adapter. Slip the alligator clips onto the test probes if desired. Make sure the Voltage to the circuit being tested is turned OFF, then connect the alligator clips to the circuit. Measure frequency.

Using the 6V-4960 AC Current Probe to Measure Frequency

Illustration 31. (1) High Voltage Adapter. (2) Cable. (3) Banana Jacks.

Connect the 9U-7505 High Voltage Adapter (1) to the Multitach II as described. Connect the 6V-6014 Cable (2) to the 6V-4960 AC Current Probe. Connect the banana plugs on the other end of the cable to the banana jacks (3) on the 9U-7505 High Voltage Adapter. An alternate method is to use a 9U-5265 Adapter and 9U-7506 Magnetic Adapter Cable to connect directly to Multitach II without using the high voltage adapter.

Squeeze the handles of the probe together and place over a wire carrying the current whose frequency is being measured. A minimum of approximately 1 Amp is required to be flowing in the wire being measured to obtain a reading on Multitach II using this method. Read the frequency.

Using the 9U-5795 AC/DC Current Probe to Measure Frequency

Illustration 32. (1) High Voltage Adapter. (2) Banana Plugs. (3) Banana Jacks.

Connect the 9U-7505 High Voltage Adapter (1) to Multitach II. Connect the banana plugs on the end of cord (2) coming from the 9U-5795 Current Probe to the banana jacks on the high voltage adapter (3). An alternate method is to use a 9U-5265 Adapter and 9U-7506 Magnetic Adapter Cable to connect directly to the Multitach II without using the high voltage adapter. Refer to the 9U-5795 Tool Operating Manual and turn the current probe ON and connect the probe over a wire carrying the current whose frequency is being measured. A minimum of approximately 80 Amps is required to be flowing in the wire being measured to obtain a reading on Multitach II using this method. Read the frequency.

Printing Multitach II Measurements

Multitach II is capable of printing all measurements on a serial printer connected to the RS232 output. The following instructions describe how to install the optional RS232 output adapter and use the print function.

The 4C-9499 RS232 Adapter, includes 4C-9808 Serial Printer Cable (2). This cable has a 25-pin printer connector.

Illustration 33. (1) Cable. (2) Adapter.

Installing Optional RS232 Output Adapter

1. Remove the six screws from Multitach II rear cover and remove the cover. Use a small screwdriver to remove clips (3) that hold the RS232 cover on the top panel and remove the cover.

NOTE: The RTV sealant may first need to be removed from the back side of the RS232 cover.

Illustration 34. Remove Cover. (3) Clip.

Illustration 35. Install Adapter. (4) Standoffs.

2. Install the 4C-9499 RS232 Adapter in opening in top panel as shown in Illustration 35. Use standoffs (4) to secure adapter to top panel.

Illustration 36. Plug Connector Into Circuit Board. (5) Connector. (6) Circuit Board.

3. Plug connector (5), on adapter cable, onto the mating connector on printed circuit board (6).

4. Replace the back cover and install the six screws removed from the back.

Printing the Data

Multitach II will print only to a printer which has a serial input and Epson emulation.

1. With Multitach II OFF, press and hold the MAX-MIN key and press ON/OFF. The display will show the baud rate Multitach II is set for. If it is not the same as required by the printer, press MAX-MIN until the correct baud rate is displayed. Then press any key to exit this display. You are now ready to print.

2. There are two printing choices for a printout of the information on the display only, printing only once when PRINT is pressed, or printing continuously every 10 seconds. Also, at any time, all information in the internal memories and on the display can be printed by holding the PRINT key down for three seconds. Examples of these three printouts follow.

Illustration 38. Example Of Print Once (Prnt oncE) Printout.

Illustration 39. Example Of Print Continuous (Prnt cont) Printout.

3. The setting of the printer PRINT key can be shown on the display. To see the setting, hold down the PRINT key with Multitach II OFF, then press ON/OFF. When the display comes ON, it will show "Prnt oncE" or "Prnt cont" on it. To select the desired printing method, press PRINT and the setting will change. Leave the desired printing method on the display and exit by pressing any other key. You are now ready to print.

Illustration 40. Example Of Printout Of All Memories And Display (PRINT key held down for 3 seconds).

4. Connect the printer and press print. If you are in the "Prnt oncE" mode, one set of readings will be printed and the printer will stop. If you are in the "Prnt cont" mode, the printer will print a set of readings every 10 seconds until stopped by pressing the PRINT key again.

Checking the Operation of Multitach II

The following procedure can be used to make sure that Multitach II is operating properly and is accurate.

An accurate frequency source is required. Either the 5P-9698 Calibrator (cancelled) or an 8T-5200 Signal Generator Counter Group can be used. The 9U-7506 Magnetic Adapter Cable can be used with either unit to connect to the RPM and HZ INPUT. Use the 8T-5197 Calibrator in the Signal Generator Group to connect to the Magnetic Adapter Cable.

1. Turn ON the calibrator or signal generator counter. Read the HZ with Multitach II. The readings should agree + or - the accuracy in the specifications for both units. When measuring frequencies less than 1000 Hz, Multitach II will show 0.1 Hz resolution and will switch to the next full digit at 0.5.

2. To check the RPM function, leave the calibrator or signal generator counter connected, and use this formula to determine what RPM should show on the Multitach II display for the input frequency.

3. To check the SET POINT operation, read any RPM value as described, then press SETPOINT. Install the 8T-5111 Rack Adapter Cable and the 1P-7446 Rack Cable in the SETPOINT INPUT being tested. With the clips on the rack cable not touching, OVERRUN should show on the display. When the clips are touching, LUG should show. Press the SAVE key and MEMORY should show on the display and be flashing. Touch the clips on the rack cable together rapidly and MEMORY should stop flashing. Change the frequency of the calibrator or signal generator. The RPM on the Multitach II display should remain constant. This checks the hold feature of SETPOINT. Press CLEAR and the Multitach II display should change to the new RPM value. Pressing MEM VALUE should bring up the last SETPOINT value measured.

4. To check the 9U-5140 Photo Pickup operation, use a photo pickup installed in one RPM and HZ input and a tachometer generator reading the same rotating device. An electric drill can be used for this. Put a piece of retro-reflective tape on the drill chuck and install the tachometer generator drive shaft in the chuck. Both pickups should read the same.

NOTE: The method of using a florescent light to check the older photo pickups will not work with the 9U-5140 Pickup because it is sensitive only to infrared light.

5. The MIN, MAX, MAX - MIN, and IN 1 - IN 2 functions can be checked using the signal generator at various frequencies and checking the results.

6. For a complete check of Multitach II, also refer to the "Settings and Displays Available From Front Panel (Not Labeled)" section of this manual, and check each of these for proper operation.

Checking and Adjusting the 5P-7360 Tachometer Generator

1. A fast and easy check of the tachometer generator can be made by connecting it to Multitach II, and rotating the shaft by hand to obtain a reading on the Multitach II. Connect Multitach II as described in the "Tachometer Generator" section of this manual.

Illustration 41. Rotate Shaft By Hand.

2. Rotate the shaft of the tachometer generator by hand as shown in Illustration 41. With the PPR set at 20, a reading of several hundred RPM should appear on the readout. If there is no reading or signal, continue the procedure.

Illustration 42. Checking Resistance. (1) Center Pin. (2) Connector. (3) Tachometer Generator.

3. Use a Caterpillar 6V-7070 Multimeter to check the resistance between the center pin (1) and the shell of connector (2) on the cable coming from the tachometer generator. The resistance should be 3800 ± 400 Ohms. Check to make sure there is no short circuit (zero ohms) between the center pin of the connector and the case of the tachometer generator (3). Using the digital multimeter, the reading should be OL (infinity) on any of the resistance ranges. If there is a short circuit, replace the tachometer generator. If these checks are satisfactory, continue the procedure with Step 4.

Illustration 43. Checking Output Voltage. (4) Locknut. (5) Magnetic Pickup. (6) Shaft.

4. Connect the tachometer generator to an AC Voltmeter, and turn the shaft with an electric drill as shown above. The output Voltage should be at least 0.50 Volts at 1200 RPM. If the Voltage is too low, adjust the tachometer generator as follows.

5. Loosen locknut (4). Turn magnetic pickup (5) clockwise while turning shaft (6) by hand. Turn the pickup until it can be felt when the internal gear teeth on shaft (6) touch the end of pickup. Hold the pickup in this position and tighten the locknut. When the locknut is tightened, the pickup will move slightly away from the gear teeth. Turn the shaft by hand to make sure the gear teeth do not touch the end of the pickup. Repeat Step 4 above to check the output Voltage. If the Voltage is not sufficient, repeat the adjustment.

Service

If the Multitach II does not operate correctly, recharge or replace the internal NiCad batteries with new ones and check the operation. If it still does not operate, refer to the "Checking the Operation of Multitach II" section in this manual. If the Multitach II is found to be faulty, contact the Caterpillar Service Technology Group for information on how to obtain the needed repair service.

Caterpillar Service Technology Group provides the instruments user with a warranty of one year from purchase date. If the reason for failure is determined to be abuse, the warranty is declared void. Any out-of-warranty repairs will be charged to the owner.

For any product support questions with your instrument, contact your Caterpillar or CSTG at:

1-800-541-8665 (Inside Illinois)

1-800-542-8665 (Outside Illinois)

1-800-523-8665 (Canada)

Hotline E-Mail "CSTG"

022-849-4036 (Geneva Phone)

022-849-4929 (Geneva Fax)

36CSTG (COSA E-Mail)

If the instrument, or any part of it needs repair, then contact and send it to:

ATS (Advanced Technology Services) 8201 North University Avenue Peoria, Illinois USA 61615

Phone: 1-800-328-7287 (Inside USA)

1-309-693-4000

1-309-693-4170 (Fax)

E-Mail "repair@advancedtech".com

Repair Parts Available for Multitach II:

9U-7508 Multitach II Group Foam Insert

9U-7507 Multitach II Photo Group Foam Insert

9U-7322 Multitach II Touch Switch

For information on service tools or shop supplies, contact Caterpillar Service Technology Group on:

1-800-542-8665 (USA)

1-800-541-8665 (Illinois)

1-800-523-8665 (Canada)

404435 (Telex)

1-309-675-6650 (Fax)

or

+41 (22) 849 40 36 (Geneva Phone)

+41 (22) 849 49 29 (Geneva Fax)

36CSTG (COSA E-Mail Address)