Usage:
Components Of The 6V3121 Multitach Group
1. 6V3072 Carrying Case
6V4863 Foam Insert (not shown)
6V6045 Small Accessories Case (not shown)
FORM SEHS8009 Accessories Case Label
2. 5P7366 Power Cable
3. 6V2198 Photo Pickup Extension Cable
4. 5P7360 Tachometer Generator
5. 5P1759 Tachometer Drive Group
6. 6V93 Retro Reflective Tape (for replacement)
7. 6V2100 Multitach
8. 6V3136 Photo Pickup
9. 6V3137 Magnetic Base for Photo Pickup
10. 5P7362 Magnetic Input Cable
11. 6V3138 Extension Rod for Magnetic Base
FORM SEHS7729 - Operation Instructions in lid of carrying case
FORM SEHS7712 - Operation Instructions on rear of 6V2100 Multitach
FORM SEHS7939 - Label on carrying case
Optional Items For Use With The 6V3121 Multitach Group
1. 8L4171 Magnetic Pickup (general purpose)
2. Magnetic Pickup (for timing hole)
8T5184 - 3.5" (88.9 mm) long (not shown)
8T5185 - 7.00" (177.8 mm) long (not shown)
6V2197 - 4.5" (114.3 mm) long
3. 6V2199 Transducer Adapter, 1/8 inch
4. 6V3093 Transducer Adapter, 1/4 inch
5. 6V93 Retro Reflective Tape, replacement roll of 150 ft. (45.7 meters)
6. 6V4156 Magnetic Pickup Adapter Cable
7. 6V3061 Photo Pickup Replacement Lamp
6V3082 Magnetic Extension Cable (not shown)
Features Of The 6V3121 Multitach Group
- R/MIN READOUT:
- R/MIN (revolutions per minute) is directly displayed on a liquid crystal digital four digit display in numbers .5" (12.7 mm) high. The display is visible in direct sunlight and in low light conditions.
- PROGRAMMABLE:
- The Multitach can be programmed by using the touch switches on the front panel. The multitach will then display R/MIN directly from an input signal with any number of P/REV (pulses per revolution) between 1 and 256. The multitach will also directly display R/MIN with an input signal of 0.5 P/REV.
- TYPE OF PICKUP:
- R/MIN can be measured by using either the photo pickup and retro reflective tape, or a magnetic pickup or tachometer generator.
- INPUTS:
- Connections are provided for photo pickup and magnetic pickup or tachometer generator. There is also a connection for power input.
- INPUT SELECTION:
- Touch switches are used to select either photo or magnetic input. In indicator light shows which input is being used.
- SIGNAL INDICATOR:
- An indicator light shows when an input signal is present, and flashes on and off when low R/MIN signals are present.
- POWER:
- Power supply for the multitach comes from an external vehicle battery or any DC voltage source from 11 to 40 volts at .3 amps.
- POWER POLARITY:
- Power input to the multitach is not polarized. Positive or negative can be connected to either input connection.
- CALIBRATION:
- No adjustments are necessary for accuracy, since the multitach is designed to maintain its original accuracy for the life of the instrument. However, accuracy can be checked by using a 5P9698 Calibrator.
- OVERRANGE:
- Overrange in either the R/MIN or P/REV mode is indicated on the digital readout by the removal of all numbers and the display of three decimal points.
- P/REV IDENTIFICATION:
- The P/REV number which has been programmed into the multitach can be displayed on the digital readout. When displayed, this number flashes on and off.
Specifications
- INPUT POWER REQUIRED:
- External power source of 11 to 40 volts DC at .3 amps. The vehicle battery or another external power supply can be used.
- MEASUREMENT RANGE:
- Range of multitach is 40 to 9999 R/MIN (revolutions per minute).
- PULSES/REVOLUTION RANGE:
- The multitach can be programmed for .5 P/REV and from 1 to 256 P/REV (pulses per revolution) to provide a direct R/MIN readout on the digital display.
- ACCURACY:
- ± 1 R/MIN at 40 to 3000 R/MIN with P/REV up to 150. ± 1 R/MIN at 40 to 9999 R/MIN with P/REV up to 50. See chart below for other combinations of R/MIN and P/REV.
- RESOLUTION:
- ± 1 R/MIN.
- READOUT UPDATE RATE:
- Less than four seconds for 40 to 299 R/MIN. Less than three seconds for 300 to 349 R/MIN. One second for 350 to 9999 R/MIN.
- INPUT SENSITIVITY:
- 0.10 volt peak positive signal on either photo or magnetic input.
- INPUT IMPEDANCE:
- 900 ohms - magnetic 82K ohms - photo
- PHOTOHEAD RANGE:
- Minimum of 18" (457) with 6V93 Retro Reflective Tape target.
- OPERATING TEMPERATURE
- 0°F to 140°F (-17°C to + 60°C).
- STORAGE TEMPERATURE:
- -40°F to +212°F (-40°C to +100°C).
- SIZE:
- 6V3121 Multitach Group - 15.5" (394 mm) × 12.25" (311 mm) × 4" (101 mm) 6V2100 Multitach - 7.5" (190 mm) × 4.4" (112 mm) × 1.6" (40 mm).
- WEIGHT:
- 6V3121 Multitach Group - 8 lbs. (3.6 kilograms). 6V2100 Multitach - 1 lb (.45 kilograms).
Accuracy Chart For 6V2100 Multitach
To determine accuracy, find the maximum R/MIN that is to be measured in the left column. From that R/MIN number, move to the right and read the accuracy number that is directly under the P/REV number being used. For maximum accuracy, always use the smallest P/REV possible.
Connections And Controls For 6V2100 Multitach
1. Power Input Connector: Connection for 5P7366 Power Cable to 11 to 40 volts DC at .3 amp source.
2. Magnetic Input Connector: Connection for 5P7362 Magnetic Input Cable which connects to a magnetic pickup or a tachometer generator.
3. Photo Input Connector: Used to connect photo pickup to multitach with the 6V2198 Photo Pickup Extension Cable.
4. Digital Readout: A four digit LCD display used to indicate the R/MIN and P/REV. Will indicate from 0000 to 9999. Also shows three decimal points to indicate an overrange condition.
5. Photo Input Light: Indicator light comes on when photo input has been selected with the PH switch.
6. Magnetic Input Light: Indicator light comes on when magnetic input has been selected with the MAG switch.
7. No Input Signal Light: Indicator light comes on when no input signal is present on the input selected. Light will flash on and off when a low R/MIN signal is being measured.
8. R/MIN Switch: Push switch to read R/MIN (revolutions per minute) on the display after the correct P/REV (pulses per revolution) number has been entered.
9. P/REV Switch: Push switch to display pulses per revolution number that was programmed into the multitach. The display will flash the P/REV number on and off to indicate it is in this mode. When the P/REV number shows on the display, it can be changed by using the number switches.
10. CLR Switch: If the P/REV number is being displayed on the readout, pushing this switch will clear the display to 0 and will reset the P/REV number programmed into the multitach to zero. A new P/REV number can then be entered.
11. PH Switch: Pushing this switch places the multitach in the phototach mode by connecting the PHOTO input connector signal to the microcomputer.
12. MAG Switch: Pushing this switch places the multitach in the magnetic mode by connecting the MAG input connector signal to the microcomputer.
13. Number Switches: The eleven number switches are used for entering the P/REV number into the multitach memory. The 0.5 switch can only be used by itself, and not with another number switch.
Operation Instructions
The multitach is equipped with an automatic overrange indicator. Whenever the R/MIN number is larger than 9999, or when the P/REV number is out of specification, all numbers will disappear from the digital display and only three decimal points will be seen as shown above. This permits the user to correct the problem to prevent a measurement error.
A Connection Of Power To The Multitach
An external power source must be used with the multitach. This power source can be a battery or other power supply capable of providing a voltage between 11 and 40 volts DC at .3 amps. If the R/Min of an engine is to be measured, the engine's battery can be used to power the multitach. If no battery is available, a battery charger or other power supply can be used provided the output is in the correct range. For portable use, two 6 volt lantern batteries connected in series to provide 12 volts can be used. Use the following procedure to connect the multitach to the power source.
1. Connect 5P7366 Power Cable (1) to connector (2) on the multitach (labeled 11 to 40 VDC).
NOTE: Since the multitach power input is non-polarized, either positive or negative supply terminal can be connected to either input clip of the power cable.
2. If the power source or battery is on a vehicle or engine, connect one of the input clips of the power cable to the frame of the engine or vehicle. Make sure this clip is in contact with bare metal. If the power source is not connected to the frame, connect the input clip directly to either terminal of the power source.
3. Connect the other input clip of the power cable to the power source or battery terminal which is not connected to the frame. On a vehicle, this clip can also be connected to any wire or terminal where the battery voltage is available.
4. Turn on the disconnect switch or power source switch. Observe MAG input light (3) and PHOTO input light (4) on the multitach. If either one of these lights is on, this indicates that power is being supplied to the multitach and the instrument is now ready for use.
B Using The Multitach With Photohead Input
1. Connect the power to the multitach as shown on page 6.
2. Clean an area on the outside of the part whose rotation is to be measured. Cut a piece of 6V93 Retro Reflective Tape approximately 3/4" (20 mm) long. Remove the protective backing and put the tape on the clean area of the part.
NOTE: One piece of tape is usually enough, but more may be used if necessary. If more than one piece is used, put the pieces at least one tape width apart. For slow speed measurements, a more stable reading will result if more than one piece of tape is used.
3. Connect 6V2198 Photo Pickup Cable (1) to the PHOTO IN terminal of the multitach. Connect 6V3136 Photo Pickup (2) to the other end of the cable. Loosen thumbscrew (3) on 6V3137 Magnetic Base (4), and install pickup (2). Tighten thumbscrew (3).
4. Put the magnetic base on a metal surface up to 18" (457 mm) away from the reflective tape. Loosen thumbscrew (5) on the base to adjust the light beam coming from the photo pickup so it hits the reflective tape. If the photo pickup light can not be seen because of high ambient light conditions, aim the photo pickup carefully toward the tape by sighting from behind it. Final adjustment can be made by observing the NO INPUT SIGNAL light (6) on the multitach. If the photo pickup will not reach far enough to allow correct alignment, 6V3138 Extension Rod (7) can be used.
5. To read the speed directly in R/MIN on the readout, the correct P/REV (pulses per revolution) number must be entered into the keyboard. When using the photo pickup, the P/REV number is the number of pieces of tape on the rotating part whose speed is to be measured. To enter this number, press P/REV switch (8), then press CLR switch (9). The display should now flash 0. Press the number switch required to enter the number of pieces of tape (usually one). The number entered must show on the readout, and flash on and off. Press PH switch (10). PHOTO INPUT light (11) must be on.
6. Press R/MIN switch (12) to read the speed of the rotating part. The speed should appear on the digital readout. If the reading is not stable, look at NO INPUT SIGNAL light (6). The light must be off for high speed measurements, and flash on and off at a constant rate for low speed measurements. If it does not, loosen thumbscrew (5) and adjust the position of the photo pickup while observing NO INPUT SIGNAL light (6). When the light is steady, tighten thumbscrew (5).
7. Read the speed of the rotating part on the digital display. The number shown is in revolutions per minute.
C Using The Multitach With Magnetic Input
1. Select and install magnetic pickup or Tach Generator as described in Section D. Connect the power to the multitach as shown on page 6.
2. Connect magnetic input cable (1) to the multitach. Connect the other end of the input cable to the magnetic pickup or tachometer generator.
| NOTICE |
|---|
Do not let metal end (A) of input cable (1) touch the machine frame during operation of the multitach. Always have the cable plugged into the tachometer generator if the cable is connected to the multitach. |
3. Press P/REV switch (2) and observe the number flashing on the readout. If it is not the correct P/REV number, press CLR switch (3) to make the readout go to 0. For magnetic operation, the P/REV number is usually the number of gear teeth on the gear that the pickup is sensing. Press the number switch (or switches) needed to enter the number, one digit at a time. If the desired number has more than one digit, start with the left digit first. The number entered should show on the readout, and flash on and off. Press MAG switch (4). MAG INPUT light (5) should be on.
4. Press R/MIN switch (6) to read the speed of the rotating part on the digital readout. If the reading is not stable, check NO INPUT SIGNAL light (7). Light (7) must be off at high speeds, and flashing at a constant rate at low speeds. If it is not, the magnetic pickup may need adjustment. This can usually be done by moving the pickup closer or farther away from the gear teeth or the metal that it is sensing.
D Selection And Installation Of Magnetic Pickup
The multitach can measure the R/MIN of a rotating part by using almost any type of magnetic pickup or generator. The only requirement is that the output signal is within the specifications of the multitach. The multitach will count the number of pulses and display the R/MIN (revolutions per minute) if the correct P/REV (pulses per revolution) number has been entered on the keyboard. The P/REV number must also be within the specifications of the multitach.
The 5P7360 Tachometer Generator has been provided with the multitach group for measuring R/MIN of Caterpillar engines. Also available as optional items are the 8L4171 Magnetic Pickup and the 6V2197 Magnetic Pickup.
5P7360 Tach Generator
The 5P7360 Tach Generator can be used on engines equipped with a tachometer drive. To use the tach generator, remove the engine's Service Meter and install 5P1759 Tach Drive Group (1) and 5P7360 Tach Generator (2). If the tach generator is mounted on the engine's tach drive, the P/REV number is 10 (tach drive runs at one-half engine speed). On applications where the tach generator is directly driven, the P/REV is 20.
| NOTICE |
|---|
Never use a 9S3047 Tachometer Generator (blue in color) with the multitach, or damage to the multitach may result. Use only a 5P7360 Tachometer Generator. |
8L4171 Magnetic Pickup (Optional)
This magnetic pickup will provide an output pulse which can be counted by the multitach whenever the sensing tip of the pickup is within 1/8" (3.2 mm) of a rotating ferrous metal part. Therefore, this pickup can be used to sense the gear teeth on an engine flywheel to obtain engine R/MIN. Some Caterpillar engines are equipped with a threaded hole in the flywheel housing which will accept this pickup, as shown above.
To install the magnetic pickup, remove the plug from the flywheel housing. 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.
The P/REV number to be programmed into the multitach will be the number of teeth on the flywheel gear. A 6V4156 Adapter Cable is needed to connect the magnetic pickup to the 5P7362 Magnetic Input Cable of the multitach.
8T5184,8T5185 Or 6V2197 Magnetic Pickup (Optional)
The magnetic pickup has a small .25" (6.4 mm) diameter body to permit it to be installed in the static timing hole on Caterpillar engines. 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 P/REV number for this application is 1.
To use the magnetic pickup, 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 6V2199 or 6V3093 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 1/16" (1.6 mm) and tighten the locknut finger tight. Connect the output lead of the pickup to the 5P7362 Magnetic Input Cable of the multitach.
Checking The Operation Of The Multitach
The following procedure can be used to ensure that the multitach is operating correctly. The only equipment required that is not provided in the 6V3121 Multitach Group is a power source, a fluorescent light, and a 5P9698 Calibrator.
A Connection Of Power
1. Connect 5P7366 Power Cable (1) to multitach connector marked 11 to 40 VDC.
2. Connect the clips of the power cable to a DC (direct current) power source with a voltage between 11 and 40 volts and a current of 0.3 amps. Either clip of the cable can be connected to either power source terminal since these input leads are not polarity sensitive.
3. Observe the MAG and PHOTO INPUT lights (2) and (3). If either of them is on, this indicates the multitach has power and is ready to use.
B Checking Overrange Indicator
The overrange indicator can be checked for operation by entering a P/REV number which is larger or smaller than the specified range. The acceptable P/REV numbers are any number from 1 to 256, and also the number 0.5.
1. To check the overrange indicator, press the P/REV switch (1); then press CLR switch (2) to remove the P/REV number.
2. Press the 2 switch, then the 5 switch, and then the 7 switch to enter the P/REV number 257. This number is larger than the acceptable P/REV range of the multitach, and the display should indicate an overrange. The display should show only three decimal points that flash on and off.
3. The overrange indicator can be checked for other values also. It should indicate an overrange for all P/REV numbers entered which are outside the specifications of the multitach. It should also indicate an overrange when any R/MIN number goes above 9999.
C Checking Magnetic Operation
1. Press P/REV switch (1), then press CLR switch (2). Press 1 switch, then press the 0 switch. The digital readout should now be reading 10 and flashing on and off. This shows that the multitach is programmed for a P/REV number of 10.
2. Obtain a 5P9698 Calibrator as shown above. Remove small adapter plug (3) from the clip. Install adapter plug (3) into plug (4) of the calibrator cable. Connect calibrator cable (5) to the MAG IN connector of the multitach as shown. Make sure calibrator knob (6) is in the OFF position.
3. Press MAG switch (7) on the multitach. The MAG INPUT light (8) should be on, and then the NO INPUT SIGNAL light (9) should be on. Press R/MIN switch (10) to read revolutions per minute. The display must read 0.
4. Turn knob (6) on the calibrator to the 400 OUTPUT HZ position. Check to be sure BATTERY indicator needle (11) is in the white part of the scale. NO INPUT SIGNAL light (9) on the multitach should go off, and the number 2400 (plus or minus 1) should appear on the digital readout. If this number is correct, the multitach is working properly. This is a check of the operation of the multitach in the MAGNETIC mode at 10 P/REV and 2400 R/MIN.
5. Operation of the multitach can also be checked for other R/MIN values by changing the OUTPUT HZ number on the calibrator, and/or by changing the P/REV number on the multitach. The R/MIN number which should appear can be determined by using the following formula, and then checking the reading accuracy as shown in the chart on page 4.
6. To change the P/REV number, press P/REV switch (1), then press CLR switch (2). Press the number switches one digit at a time starting with the left digit of the number (if the number has more than one digit). The new number should be flashing on and off on the digital readout. If the number shown is the number desired, press R/MIN switch (10) to read the revolutions per minute value.
7. Disconnect calibrator cable (5) from the multitach, and rotate calibrator knob (6) to the OFF position. If PHOTO OPERATION is to be checked, do not disconnect the power cable.
NOTE: Magnetic operation of the multitach can also be checked by using one of 5P7360 Tach Generator operational checks shown on page 13.
D Checking Photo Operation
1. Press P/REV switch (1), then press CLR switch (2). Press 1 switch, then press the 0 switch. The digital readout should now be reading 10 and flashing on and off. This shows that the multitach is programmed for a P/REV number of 10.
2. Connect 6V2198 Photo Pickup Extension Cable (3) to the PHOTO IN connector of the multitach. Connect the other end of the cable to 6V3136 Photo Pickup (4).
3. Look into the end of photo pickup (4). A bright light should be on inside of the pickup. Point the light toward an object approximately 1 ft. (0.3 m) away. A small spot of light should appear on the object. If the light is not on, the bulb inside the photo pickup may be defective. Replace the bulb as shown on page 16.
4. Press PH switch (5). PHOTO light (6) must come on; NO INPUT SIGNAL light (7) must also be on.
5. Hold the light emitting end of photo pickup (4) directly in front of a fluorescent light, and watch for NO INPUT SIGNAL light (7) to go off. Hold the pickup in the position that keeps light (7) off, as shown above.
6. Observe the reading on the digital display. It should be one of the following values, depending upon the frequency of the AC power operating the fluorescent light.
50 Hz (50 cycles per second AC) = 600 reading on multitach
60 Hz (60 cycles per second AC) = 720 reading on multitach
7. The above multitach readings must be within ± 1 of the number specified. However, this test is only accurate if the frequency of the AC power to the fluorescent light is correct.
8. The photo check can also be made for other values of P/REV by changing the number in the multitach. To change the P/REV number, press P/REV switch (1) and then CLR switch (2). Press the number switches one digit at a time starting with the left digit of the number (if the number has more than one digit). The new number should be flashing on and off on the digital readout. The R/MIN number which should appear for various P/REV settings can be determined by using the following formula, and then checking the accuracy as shown in the chart on page 4.
Checking And Adjusting The 5P7360 Tach Generator
1. A fast and easy check of the tach generator can be made by connecting it to the multitach, and rotating the shaft by hand to obtain a reading on the multitach. To use the multitach, connect the power to the multitach as shown on page 6.
2. Connect magnetic input cable (1) to the multitach. Connect the other end of the input cable to the tachometer generator.
3. Press P/REV switch (2) and observe the number flashing on the digital readout. If the number shown is not 20, press CLR switch (3) to make the readout go to 0. Press the 2 switch, then the 0 switch to enter the correct number. The number entered should show on the digital readout and flash on and off. Press MAG switch (4). MAG INPUT light (5) should be on.
4. Press R/MIN switch (6), and rotate the shaft of the tach generator by hand. A reading above several hundred R/MIN should appear on the digital readout after a short period of time. If there is no indication, continue with the following procedure.
5. Use a Caterpillar 6V3030, 6V7070 or 6V7800 Digital Multimeter (or other multimeter) to check the resistance between the center pin and the shell of connector (7). 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 tach generator. Using the digital multimeter, the reading should be OL (infinity) on any of the resistance ranges. If there is a short circuit, replace the tach generator. If these checks are satisfactory, use the following procedure to check the output of the tach generator.
6. Connect the tach generator to an AC voltmeter, and turn the shaft with an electric drill as shown above. The output voltage should be at least .50 volts at 1200 R/MIN. If the voltage is too low, adjust the tachometer generator as follows.
7. Loosen locknut (8). Turn magnetic pickup (9) clockwise while turning shaft (10) by hand. Turn pickup (9) until it can be felt when the internal gear teeth on shaft (10) touch the end of pickup (9). Hold pickup (9) in this position and tighten locknut (8). When locknut (8) is tightened, the pickup will move slightly away from the gear teeth. Turn shaft (10) by hand to make sure the gear teeth do not touch the end of pickup (9). Repeat step 6 above to check the output voltage.
Checking The 5P7366 Power Cable
1. Use the 8T0500 or 8S4627 Circuit Tester, or the Caterpillar Digital Multimeter to check for continuity in each wire. Each wire should measure zero ohms on the 2K ohm scale of the multimeter.
2. Check for short circuits between the conductors. The measurement should be OL (infinity ohms) on the 2K ohm scale of the multimeter.
Checking The 6V2198 Photo Pickup Extension Cable
1. Use the 8T0500 or 8S4627 Circuit Tester or the Caterpillar Digital Multimeter to check for continuity in each wire. Each wire should measure .000 K ohms on the 2K ohm scale of the multimeter.
2. Check for short circuits between the conductors. The measurement should be 0L (infinity ohms) on the 2K ohm scale of the multimeter.
Checking The 6V3136 Photo Pickup
A fast and easy way to check the photo pickup is to perform the photo operation check on page 12. However, if the photohead does not work, it will not be known if the problem is in the photo pickup or in the multitach. To determine if the photo pickup is good, use the following procedures.
A Checking The Photo Pickup Lamp
1. Use an ohmeter to measure the resistance between pins 3 and 5 of the connector. The lamp resistance should measure almost zero ohms (2 to 3 ohms is typical) if the lamp is good. If the lamp is burned out, the resistance will be infinite ohms (0L on the multimeter). Replace the lamp as shown on page 16.
B Checking The Photosensor
1. If the lamp in the photo pickup is good, but the pickup will still not work, the photosensor may be defective. To check the photosensor, use an ohmmeter to measure the resistance at the connector.
2. Put the black (negative) lead of the ohmmeter on pin 2, and the red (positive) lead on pin 4. Cover the lens end of the photo pickup so no light can enter. The ohmmeter should read approximately infinite ohms (0L on the multimeter).
3. Hold the lens end of the pickup near a bright light. The resistance should now be low enough to measure on the ohmmeter. The resistance should vary depending on how close to the light the pickup is held, and the brightness of the light. The highest scale on the ohmmeter should be used for this test since the resistance measured will be from several thousand to several hundred thousand ohms. If the resistance does not change when the pickup is placed near a light, the photosensor is defective and the pickup must be replaced.
C Replacing The Lamp In The 6V3136 Photo Pickup
If the lamp in the photo pickup has been checked and found defective, it can be replaced with a new 6V3061 Lamp. To do this, the photo pickup must be disassembled as follows.
1. Remove two screws (1) from pickup cap (2). Pull the pickup halves apart, being careful not to let lens (3) fall out of cover (4). Slide cover (4) completely off inner body (5) of the pickup.
2. Hold cap (2) and bend inner body (5) back so lamp socket (6) can be removed. Pull the lamp socket completely out of the inner body, being careful not to damage any of the wires. Unscrew the lamp and install a new 6V3061 Lamp. Put the lamp and socket back in position in the inner body.
3. Carefully remove lens (3) from cover (4) by turning the cover upside down. Red lens retaining washer (7) may also come out of cover (4). Clean lens (3) before installation back in cover (4).
4. To install lens (3), hold cover (4) vertical, so the end with screw holes (A) is up and the other end is down. Install red washer (7) in cover (4), and turn the washer as necessary so it is against the bottom end of the cover. Pick up lens (3) and hold it over the cover so the curved side of the lens is down. Drop the lens into the cover so it is against the red washer. Make sure the curved side of lens (3) is toward the red washer. If not, use a pencil to turn the lens. While holding cover (4) in a vertical position, slide inner body (5) into cover (4). When inner body (5) is in position in cover (4), put cap (2) in place on cover (4) and install screws (1). Make sure the curved side of the lens is toward the red washer. If it is not, disassemble the pickup and put the lens in the correct position.
5. To test the lamp, connect the pickup to the multitach. With the light toward an object about 1 ft. (.3 m) away from the end of the pickup, the spot of light on the object should be a small circle approximately .5 in. (12.7 mm) in diameter straight out from the end of the pickup. If the light is not satisfactory, a different 6V3061 Lamp should be installed in the pickup.
Result Of Incorrect Connection Of Power To Earlier Multitachs Without Fuses (Multitachs Built Before May 1, 1981)
All multitachs built after May 1, 1981, have miniature fuses soldered in place on the input power lines. These fuses protect the multitach from damage due to incorrect power connections and shorted tachometer generators. Earlier multitachs that have been damaged due to incorrect connection of power will not operate or show any display. It may be possible to repair the damage to the multitach using the following procedure; however, repair should be attempted only by personnel familiar with electronic repair.
1 Remove six screws (1) from the rear cover of the multitach. Pull cover (2) off the unit.
2 Remove six screws (3) that hold the printed circuit board in place. Do not remove two screws (4) that are behind the display window. Lift out the printed circuit board and disconnect the blue rectangular connector (5) from the circuit board. Remove the circuit board.
3 Look for printed circuit traces that have been burned through. These can be repaired by soldering a short piece of bare copper wire across the gap in the trace.
4 If a printed circuit board trace has been burned through, the bridge rectifier (6) has probably also been damaged. Unsolder and remove rectifier (6), being careful not to damage the printed circuit board. A new 6V4965 Rectifier should be installed in place of rectifier (6). Make sure the + and - sign on the rectifier are matched with the + and - sign on the circuit board during installation of the new part.
5 After the multitach has been repaired, install two 6V4956 Fuses by removing the wires that go from the 11 to 40 VDC connector to the printed circuit board. Install two fuses (7) in place of these wires.
6 If it was not possible to repair the multitach with the above procedure, the multitach should be returned to the manufacturer for repair. See page 19 for the correct procedure to use when returning the multitach.
Checking And Replacement Of Fuses (Multitachs Built After May 1, 1981)
1 Remove six screws (1) from the rear cover of the multitach. Remove rear cover (2). Use a 6V3030 Digital Multimeter to check fuses (3). Measure from one end of the fuse to the other end of the same fuse using the 200 ohm scale. A good fuse will measure less than 1 ohm resistance. A defective fuse will measure infinite ohms (0L on the display) and should be replaced. Be sure to measure both fuses. If the fuses are covered with a clear protective coating, use the sharp pointed probes from the 6V3032 Deluxe Lead Kit to penetrate this coating and make contact.
NOTE: All multitachs built after May 1, 1981 have miniature fuses (3) soldered in place on the input power lines as shown above. Those multitachs built after November 28, 1984 do not have the miniature fuses (3), but do have two removable, fast acting fuses at location (A). The new fuses are 1 amp, 250 volt, Caterpillar Part Number 8K4644. [These 8K4644 Fuses are 1.250" (31.75) long and .250"Ø (6.35Ø).] The 8K4644 Fuse is a see-through fuse, to make it easy to see if the fuse is good or if the filament is broken.
2 If an earlier type fuse (multitachs built from May 1, 1981 - November 27, 1984) is defective, use a small soldering iron to remove it. Heat the solder joint on one end and then pull the wire out with needle nose pliers. Repeat this procedure for the other end of the fuse. Cut the leads on the new fuse to the same length as the old fuse. Heat the solder on the connector or printed circuit board, and insert the wire. Let the solder cool and repeat the procedure on the other end of the fuse. Install the rear cover. Check the operation of the multitach.
3 If it appears that a later type fuse is defective, (multitachs built after November 28, 1984), use an ohmmeter to check the fuse(s) according to Step 1. Lift out and replace the defective fuse(s). Install the rear cover and check multitach operation.
Using FT1808 Adapter Cable
Using drawing FT1808, a magnetic input adapter cable can be made for the 6V2100 Multitach. This cable can be used on engines equipped with a magnetic pickup which is used to provide a speed signal for an electronic overspeed switch or electronic governor. By connecting the lug or clip lead on FT1808 to the magnetic pickup output signal lead, engine speed can be measured on the 6V2100 Multitach. The FT1808 Cable connects to the magnetic input cable on the multitach. No ground connection is required if the engine battery is used to power the multitach. The number of flywheel teeth should be used as the PPR (pulses per revolution) number on the multitach.
The FT1808 Cable can also be used to measure alternator rotation speed by connecting the clip to the "R" terminal. Refer to Form SENR2945 Electronic Monitoring System (EMS) service manual for use.
NOTE: This method will measure alternator speed, which is a ratio of engine speed.
Repair Of Multitach By Manufacturer
If the multitach does not operate correctly, the unit can be returned to the manufacturer for repair. A letter should accompany the multitach indicating the problem and the date of purchase of the multitach from Caterpillar. Multitachs less than one year old will be repaired under warranty, except for abuse. Cost of out-of-warranty repairs or abuse will be charged to the owner. If requested, the manufacturer will also install fuses in the multitach. The multitach should be returned to the following address for repair.
General Fabrication Corp1100 S.W. 11th Avenue
Industrial Park
Forest Lake, MN 55025
U.S.A.
Telephone: 612-464-5110