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The motor leads for the electric fan motor on the spindle motor are FMA and FMB.

When troubleshooting the older analog spindle amplifiers you need the AC ANALOG SERVO UNIT MAINTENANCE MANUAL B-54765E.

When troubleshooting a Spindle problem be aware that some machine tool builders set a Diagnostic bit to cause the spindle to run at a low speed (i.e. 50 RPM) when the door is open.

A symptom of a bad Spindle Encoder is that when given a run command, the motor moves slowly while making a screeching noise. When the Stop command is given the motor moves quickly in the opposite direction briefly.

The Serial Spindle information is stored in the 6000 series parameters.

You can determine if a spindle is a serial spindle by the model number. If the number is A06B-6063 to A06B-6088 it is a serial spindle.

When working with the AC Spindle manual the top parameter number is for the main spindle, the bottom number is for the second (Sub) spindle.
i.e. 0C

If a Spindle motor coasts to a stop rather than braking, check for loose belts or some other reason that would cause the pulley to slip. The reason for this is that the spindle stopping is a one shot deal. When the command is given to stop, the spindle amplifier applies a braking signal to the motor until it senses zero speed. If the belt can slip, the motor will stop and the braking signal will be removed. Once the motor is no longer in a braking condition, it is put in motion again by the momentum of the spindle and is ignored by the spindle amp.

Some machines use a Fanuc Position Coder driven by a belt on the Spindle. Parameter 6501.2 must be a 1 to turn the position coder on. If the position coder is turned off or is faulty, many of the spindle functions will not operate such as Constant Surface Speed, Rigid Tapping, etc. Another symptom of this condition is that the axes will not move when commanded to in G99 mode (Feed per Rev). Also, with most machines using the position coder, its output supplies the signal for the Actual Spindle Speed in the Program Check Screen. In this case the speed usually can still be viewed on the Operating Monitor Screen. This signal is being supplied by the spindle's motor encoder.

The position coder normally connects directly to the spindle Amplifier on JY4.

Most Fanuc AC Spindle motors have a gear on the back of the motor whose teeth are monitored by a proximity detector for position and velocity feedback. Normally, the connector for this connector consists of 6 conductors. They are Red, White, Yellow, Black, Blue, and Green. If this detector fails, the motor will usually respond to a speed command by trying to run slowly, sometimes in the wrong direction, while making a screeching noise. When commanded to stop, it may run very fast in the opposite direction and then either stop or go into an Alarm condition.

The older Digital Spindle Drive has a 5 digit LED display. In Run mode this displays the motor speed (Not spindle speed). In order to view Parameters:

1. Hold all four buttons until FFFFF flashes.
2. Release all buttons.
3. Hold MODE button in while pressing either the Up or Down button.
    (The parameter number will be displayed in order i.e. F01,F02,etc.)
4. Release the MODE button.
    (The Parameter value will be displayed)

If you have a spindle drive which has lost its Parameters you can try these just to get started:

F0      0
F1      0
F2      0
F3      0
F4      0
F5      0
F6      0
F7      100
F8      5
F9      0
F10   125
F11   147
F12   128
F13   209
F14   196
F15   60
F16   15
F17   3
F18   50
F19   10
F20   40
F21   50
F22   50
F23   100
F24   100
F25   30
F26   30
F27   30
F28   30
F29   128
F30   0
F31   0
F32   10
F33   10
F34   10
F35   100
F36   16
F37   90
F38   0
F39   0
F40   0
F41   64
F42   10
F43   16
F44   10
F45   5
F46   30
F47   8
F48   71
F49   56
F50   73
F51   2
F52   127
F53   11

To initialize the NVRAM:

1. Power down.
2. Move shorting pin (S1) to TEST position.
3. Power on.
4. Hold all four switches until FFFFF is displayed.
5. Hold the MODE button and press the UP button until FC-22 is displayed.
6. Hold the DATA SET button until GOOD is displayed.
7. Power down.
8. Move shorting pin back to normal position.
9. Power on.

This procedure is necessary when the NVRAM has been replaced or when alarm 17 or 23 has occurred. Anytime you have an alarm which will not go away, you can try this. Alarm AL-23 must be cleared this way, it will not go away by cycling power.

(The values in parentheses are Standard Settings)

F-00   Display of Spindle RPM

F-01   1 = Use (MRDY) Machine Ready Signal 
           0 = Do not use MRDY

F-02    1 = Use Override Function 
           0 = Do not use Override Function

F-03   Setting of Override Range   

F-04   Setting of Speed Command Voltage   
          1 = Use of D/A Converter
(0)      0 = External Analog Command

F-05   Setting of Maximum RPM
(*)      Standard Specification     High Speed Specification
          0=5000 RPM                    0=10000 RPM
          1=6000 RPM                    1=12000 RPM
                                                   2=15000 RPM
                                                   3=20000 RPM

F-06   Pattern Setting of Output Limit
(0)      0=No output limiting
          1=Output is limited only at acceleration/deceleration.
          2=Output is limited only during normal running not at accel/decel.
          3=Output is limited at accel/decel and during normal running.

F-07   Setting of limit value at output limit.

F-08   Setting of delay time before shut off of motor.
(5)      Delay Time = (Set Value x 40 milliseconds).

F-09   1 = Motor is shut off by Machine Ready Signal (MRDY).
(0)      0 = Motor is not shut off by MRDY.

F-10   Velocity Deviation Offset Adjustment at Forward Rotation Command

F-11   Velocity Deviation Offset Adjustment at Reverse Rotation Command. (SRV)

F-12   Velocity Deviation Offset Adjustment at Orientation Command. (OCR)

F-13   RPM Adjustment of Forward Rotation.

F-14   RPM Adjustment of Reverse Rotation.

F-15   RPM at Command Voltage of 10vdc. RPM= Setting x 100rpm.

F-16   Detection Range of Speed Arrival Signal (SAR)
(15)    Detection Range = Within +/- Setting, in percent of, commanded RPM.

F-17   Detection Level of Velocity Detection Signal.
(3)      Detection Level = Less than Setting, in percent, of commanded RPM.

F-18   Torque Limit.
(50)    Torque Limit = Less than Setting, in percent, of Maximum Output.

F-19   Acceleration/Deceleration Time.
(10)    Time = Setting, in seconds.

F-20   Limiting of Regenerated Power (Adjustment of Deceleration Time).
(60)    Setting Range = 0 -100

F-21   Velocity Control Phase Compensation P: High Gear (CTH-1)

F-22   Velocity Control Phase Compensation P: Low Gear (CTH-0)

F-23   Velocity Control Phase Compensation P at Orientation: High Gear

F-24   Velocity Control Phase Compensation P at Orientation: Low Gear

F-25   Velocity Control Phase Compensation I: High Gear (CTH-1)

F-26   Velocity Control Phase Compensation I: Low Gear (CTH-0)

F-27   Velocity Control Phase Compensation I at Orientation: High Gear

F-28   Velocity Control Phase Compensation I at Orientation: Low Gear

F-29   Velocity Detection Offset

F-30   Adjustment of RPM Display

F-31   Setting of Rigid Tap Mode

F-32   Setting of Normal Motor Voltage

F-33   Setting of Motor Voltage during Orientation

F-34   Setting of Motor Voltage during Rigid Tapping

When the Spindle is given an S command it is multiplied by the Override signal (50-120%), the result is sent to the drive as a speed command. It is sent in either Binary or BCD form. If it is sent as Binary, it is received at pins 33-44 of CN1 on the drive. If it is sent as BCD, it is received at pins 33-40. In either case this signal is derived by turning outputs on or off generating ones or zeros. In older controls this was done by a Magnetic Sequencer. On newer controls it is done by the drivers on the I/O board. Typically the driver will turn on and apply 0v to the pin (current sinking). In some cases this driver can fail and the speed override will be ineffective. Also the same driver may be responsible for sending the signal which tells the drive to use the override signal rather than the variable resistor (speed pot). In this case, the speed pot will control the spindle speed regardless of mode selected.(Jog, MDI, etc.)

Older Spindle Amplifiers have three terminals labeled
0M  SM  LM. These correspond to: 0M - 0 volts
                                                        SM - Spindle Speed (0-10 VDC)
                                                        LM - Spindle Load  (0-10 VDC)

If after the NC power has been turned on, the LED display of the Spindle amplifier does not go to 00 but instead it continues to flash --, check the following:

1. Only one spindle amp is installed but the dip switch setting is such that   the NC is looking for two amps. Dip switch 1 should be set to off.

2. The NC parameters are set in such a way that an Alpha series (Serial Spindle) can be used. Check the 
    parameters related to Serial Spindle (6500).

3. Check the cable connections especially the I/O Link.

Spindle Amplifier DIP Switches:

SPM -2.2 to -11 Types I and II have no jumper plug or DIP switches.

SPM -15 to -30 Types I and II and SPM -11 to -30 Type III have 7 DIP switches. Their functions are as follows:

S1     If two SPMs are connected to one serial interface cable, S1 is set to ON in one SPM and to OFF in the 
         other. Factory setting is OFF.

S2     If an analog filter is used at the load meter output, S2 is set to ON. If not, it is set to OFF.
         Factory setting is ON.

S3     If an analog filter is used at the speed meter output, S3 is set to ON. If not, it is set to OFF. Factory setting is ON.

S4,S5  Reference switch (external reference signal receive function) setting for the main spindle.

       S4 ON/S5 OFF  Reference switch of NPN type (Pull up)
       S4 OFF/S5 ON  "         "      "  PNP   "  (Pull down)
       S4 OFF/S5 OFF The external reference signal receive function.

S6,S7  Reference switch (external reference signal receive function) setting for sub-spindle.

       S6 ON/S7 OFF Reference switch of NPN type (Pull up)
       S6 OFF/S7 ON  "         "      "  PNP "    (Pull down)
       S5 OFF/S7 OFF The external reference signal receive function is  not used.

On an AC Spindle Servo Unit alarms are indicated by the use of four LEDs. They are mounted on the top board and labeled 8  4  2  1. They are used in combination to indicate alarms 1 to 15. The alarm numbers correspond closely to those on all spindle amplifiers.  A full description of the alarms along with much more information can be found in the manual B53425E. If you have problems with an AC analog servo unit, check the AC Servo Unit Maintenance Manual B-54765E.

If a spindle coasts to a stop check for a blown fuse on the regenerative circuit in the spindle amp.

On machines with older spindle drives, the spindle orientation is done by adjusting pots on an orientation board instead of parameters. In this case, the control will normally not have 6000 series parameters.

Once the Fanuc control orients it remembers the position as long as the power is on so if you adjust the parameter you must cycle power.

Another mistake commonly made when troubleshooting spindle amplifier problems is to be sure that the amplifier is receiving a run command and speed command. You can always check diagnostic signals to determine if the spindle is being commanded to run but if you look carefully there are other clues available. For example, on most machines anytime the spindle is commanded to run something will change such as a light being turned on a CW or CCW button. Generally speaking, if there is something wrong with a Fanuc module, it will give some sort of alarm. Also, if a run command is received at the amplifier, the amplifier will give some indication of it. All of this is so important because a lot of machines give absolutely no indication of a problem with an ATC or pallet changer for example. Normally when there is a problem with the ATC or pallet changer, etc the amplifiers will be in a ready state but will seem to ignore a spindle command. Another thing that makes it so tough is that even though these kinds of problems will not let the spindle run, most other functions are normal such as axis movement, etc. The one thing that may be inhibited sometimes along with the spindle is Z axis movement, especially in the case of an ATC problem.

If a spindle motor exhibits noise or roughness at a certain RPM, you can try to determine if the cause is electronic or mechanical by removing the feedback cable while the spindle is running. This will cause it to coast to a stop. Just be sure not to plug the cable back in while under power.

On an Analog Spindle Drive you can check the command signal input at test points CH2 and 0V.  This is a 0-10 VDC signal. You can check the spindle motor feedback at CH3 and CH4.

For problems with orientation, first check to see if the machine uses an orientation board. If it does there is a procedure for adjustment. The usefulness of the procedure is based, in large part, on what type of orientation device the machine employs, proximity switch, magsensor, separate pulse coder, etc. For problems that concern the final position of the spindle after orientation there are three rotary selector switches on the orientation board for altering this position. They are 16 position switches designated SW1, SW2 and SW3. They can be used in combination to shift the final position of the spindle to any point radially in one revolution within .088 degrees. The following description of the adjustment assumes an orientation device whose output is 4096 pulses per revolution and a pulley ratio between the spindle motor, orientation device and spindle drive pulley of 1:1. SW1 will effectively divide the 4096 pulses by 16 so that each division of movement of this switch will cause the position to shift by 256 pulses or 22.5 degrees. SW2 will divide the 256 pulses by 16 so that each division of movement will shift the position by 16 pulses or 1.4 degrees. SW3 will divide the 16 pulses by 16 so that each division of movement will shift the position by 1 pulse of .088 degrees. As far as the direction of adjustment, generally, if the rotary switch is turned in the clockwise position the spindle will stop later in it's travel, and so a counterclockwise adjustment will cause the spindle to stop sooner in its rotation.

The LED's on the orientation board:

No.            Symbol                 Color             Description
LED 1       ORIENTATION     Green            Lights when orientation command (ORCM1, 2 on) is input.

LED 2       LOW                     Green            Lights when clutch switching signal *CTH contact is closed. It means                                                                       that clutch LOW is selected.

LED 3       IN-POSITION       Green            Lights when orientation end signal  ORAR1-2 is sent.

LED 4       IN-POSITION       Green            Lights when spindle enters within one pulse width of orientation
                                                                    command position. Adjust OFFSET adjustment RV3/RV5 so that 
                                                                    LED 4 lights at gear HIGH/LOW and the stop positions at GEAR    
                                                                    HIGH and LOW coincide with one another. 

The following adjustment procedure is for addressing problems such as hunting and roughness, etc. during spindle orientation. You can adjust only those items which appear to need adjusting but for best result you should do all seven steps.

1. Speed feedback voltage OFFSET (RV1)
    Check at TSA2 and CH14 (TSA2)
    Adjust RV1 until TSA2 voltage becomes 0vdc +/- 1mvdc.

2. Gear HIGH position gain (RV2)
    Check with spindle motion or at CH14. Set the gain to the maximum within a range where the spindle does 
    not overshoot.

3. Gear HIGH offset (RV3)
    Check at LED4 (ADJUST)
    Adjust RV3 until LED 4 lights or flickers.

4. Gear LOW position gain (RV4)
    Check with spindle motion or CH14
    Set the gain to the maximum within a range where the spindle does not overshoot.

5. Gear LOW offset (RV5)
    Check at LED 4 (ADJUST)
    Adjust RV5 until LED 4 lights or flickers.

6. Speed loop gain (RV6DC) (In case of DC spindle motor)
    Check at CH14
    Make sure that the motor is not hunting. Rigidity increases during stopping when the pot is turned clockwise.

7. Speed loop gain (RV6AC) (In case of AC spindle motor).
    Same as above.

If a spindle stalls during a cut on a machine with a high/low geared head, check the gear confirmation switches. A loose wire etc. can cause the signal to be lost and the spindle to drop out due to vibration, etc.

There are three Gain pots on the spindle orientation board A20B-0008-0030/04C, RV6, RV9 and RV12. RV6 sets the gain for High Gear, RV9 sets the gain for Low Gear. RV12 sets the overall gain. To achieve the maximum gain, turn RV12 clockwise during orientation position stop until the spindle motor starts to oscillate, then turn it counter-clockwise until the oscillation just stops.

Gain is also related to the setting of jumper SH04. The highest gain, as well as the highest orientation rpm, is achieved when the jumper is removed from the board. The next highest gain and rpm occurs when pins 1 and 2 are jumpered. The lowest gain/rpm setting is between pins 2 and 3.

The MS PEAK (RV2) pot can be used as an electronic method of adjusting the gap between the magnet and the magsensor.

When the sensor fails it is possible that the spindle will continuously rotate when spindle orientation (M19) is commanded. Nothing will stop the spindle rotation such as Reset, etc. Emergency stop will stop the spindle. In some cases you can command a spindle movement (i.e., M3 S500) while the orientation is in progress, the spindle will assume the commanded speed and can then be stopped by using the reset button. If the sensor fails, it is common to see that when the spindle is rotating continuously the MS PEAK LED and the IN POSITION FINE LED will illuminate each time the magnet passes but the IN POSITION and SLOW DOWN LEDs will not.

When working with the Spindle Servo Unit A20B-6044-H021, you may find as many as nine different PCBs used with this one amplifier. They are A20B-0009-0530, A20B-0009-0531........A20B-0009-0538. These boards are all identical, the only difference is in how the jumpers are set from the factory for different drives.

If you replace the spindle main PCB, you have to check the jumper settings. You also have to swap the ROM chip which contains the system software for the drive. This chip will be labeled MD25 ROM on the board.

Also, when working with one of these spindle drives, if when the spindle is oriented it has no torque the problem could be with the gain pot (RV12), SH04 or with the orientation board itself. In some cases the problem could be with the Gain H pot (RV6) or the Gain L pot (RV9). This is a little more complicated since some machines always orient in the same gear, typically low gear, so only RV9 would be effective. With other machines, they orient in whichever gear was last in use so you have to see if the spindle orients fine in one gear but not the other and adjust the corresponding pot. Having said all of this, a problem in which the motor has little or no torque during orientation but is ok otherwise is almost always a defective spindle PCB (A20B-0009-....)
In this case, you will normally be able to turn the spindle by hand while it is in orientation stop. In many cases when the spindle is oriented alarm AL02 will be generated. Another thing you may find in this situation is that if when the spindle is oriented, you apply consistency pressure to the spindle by trying to lightly turn it you may feel the spindle resist turning then release then resist over and over. This is due to the Orientation Time Over function which causes the orientation to be released if orientation stop position is not reached and maintained in a set period of time.

When an orientation board gets out of adjustment it can take some patience to get it back but it should not be extremely difficult. Normally when an orientation board fights you too much there is something wrong. If during the course of troubleshooting you replace the sensor, make sure to position it properly relative to the magnet. If you mount it upside down you may notice many of the symptoms above but by adjusting the orientation board you can get to a condition where the spindle almost orients but it wants to inch around. If you increase the gain enough the spindle will start rotating continuously but it's motion will be jerky. You will also notice that only the MS PEAK and the IN-POSITION FINE LEDs come on while the spindle is rotating, the IN-POSITION LED (RV6) never comes on.

When troubleshooting, you don't normally have to concern yourself with LED4 SLOWDOWN. If the spindle is not moving when M19 is commanded, slowdown is not used so the LED will not come on. If, however, the spindle is running at a speed higher than the orientation speed when M19 is commanded you should see the slowdown LED come on.

LED1 (ORIENTATION) should come on when orientation is commanded and stay on.

When the spindle has been in orientation position for a set period of time, LED6 IN-POSITION will come on and stay on, this indicates that the spindle is within one degree of orientation position. If the spindle is within .1 degree of orientation position, LED5 IN-POSITION FINE will come on. It is not necessary for LED5 to come on for the orientation completion signal to be transmitted but LED6 must be on.

LED7 TEST MODE is a red LED. This LED is on when jumper SH01 is engaged. This places the board in test mode for adjustment purposes. When this jumper is installed, pressing SW1 on the orientation board will cause the spindle to orient. It will orient again every time it is pressed. This feature is not always enabled by the MTB, most notably Mori-Seiki.

If spindle orientation position is not achieved in the set amount of time, the Orientation Time Over function will cause the spindle to release from orientation.

RV5 and RV8 adjust the slowdown time in high and low gear respectively.

RV11 POSITION SHIFT adjusts the final position during orientation stop but it can only change this position by one degree since the position itself is defined by the center of the magnet.

When adjusting the gap between the sensor and the magnet they do not have to be very close to each other. There can be as much as an inch of clearance and the magsensor will work properly. With most machines, if you move the sensor back as far as possible using all of the adjustment provided by the MTB you will still be close enough to the magnet. Just don't get too close, keep in mind that as the spindle turns, the ends of the magnet can hit the sensor if they are too close.

When a PCB is sent to Fanuc and they determine that the board is un-repairable they will put epoxy over the first eight numbers of the part number and will write NR on the board. This is to prevent the board from being sent in for repair or as a core exchange and wasting time with an un-repairable board.

Orientation board jumpers:

SH01   Places the board in Test Mode.

SH02   If pins 1 and 2 are shorted, the spindle motor rotates clockwise (as viewed from the motor shaft end)  
            when orientation is commanded after turning on NC power and before the spindle is otherwise 

If pins 2 and 3 are shorted, the spindle motor rotates counter-clock wise respective of the above conditions.

The above is true only when pins 1 and 2 of SH03 are shorted. Any other setting condition of SH03 overrides the setting of SH02.

SH03   If pins 1 and 2 are shorted, the spindle motor orients in the direction it was rotating just prior to the spindle orientation command is given. This setting essentially makes the setting of SH02 effective. If pins 2 and 3 are shorted, the spindle motor always rotates in the counter clockwise direction (as viewed from the motor shaft end). If neither of the pins are shorted, the spindle motor always rotates in the clockwise direction for orientation

SH04   If neither of the pins are shorted, the spindle orientation occurs at a set gain/speed (typically 300 rpm). If pins 1 and 2 are shorted, the initial orientation speed is limited to 1/3. If pins 2 and 3 are shorted, the initial orientation speed is limited to 2/3.

SH05   Pins 1 and 2 are shorted for a DC Spindle Servo Unit.
            Pins 2 and 3 are shorted for an AC Spindle Servo Unit.

The older spindle amplifiers have a large board that is hinged and can be swung out by removing the two screws. Make sure the power is off since the screws are very short and will fall into the amp. Behind the board in the upper left hand corner are two five amp glass fuses. These two fuses are for the fan on the amplifier and the spindle motor (terminals FMA and FMB). If one of them blows the amp will not power up (PIL lamp will be off). This green LED should always be on when the three phase power is applied. Normally in this case no spindle alarms will be issued by the CNC unless a spindle command is given. On many machines there may be a spindle error lamp that will come on as a function of the ladder. In most of these cases the alarm is generated by a fault contact output from the amp which is tied to the I/O
board as an input (X address).

Normally, if a magsensor is used with a Fanuc control it will be made by Macome. The part number will typically be BKO-C1730H02 for the Sensor and BKO-C1730H01 for the Pre-amplifier which is mounted near the sensor and connected by a cable. The output of the pre-amp goes to JY3 of the Spindle Amp.

On a 0 controlled machine with a geared spindle, if the speed displayed does not agree with the actual values you alter with parameter 540 for low gear and 541 for high gear. Program a spindle speed of 1000 RPM for each gear range and adjust the parameter until the display reads 1000 RPM.

Some machines if a spindle speed is commanded in MDI then while running the Mode is switched to Jog, MPG, etc., the speed commanded will be dropped and the spindle will assume the speed selected by the speed pot.

Some Fanuc spindle motors have a dual winding for low and high speed. In this case two contactors must be supplied by the machine builder to do the switching between windings, however the spindle amplifier determines which one is energized a any given moment. If a problem occurs in the switching circuit of the amplifier, alarm AL-15 may be generated. On an amplifier which does not have this switching circuit, AL-15 normally means the spindle amp is just defective.

In addition to the above, the Fanuc control can also use the switching function to control two spindle motors with one spindle amplifier.

Pins 1, 2 and 20 of JY1 on the spindle amplifier are for the input of the manual speed reference (analog).

Power Supplies

If a Fanuc Control's power source is a GFI circuit, it should be one designed for use with inverters. The reason for this is that the Servo Amplifier and the Spindle Amplifier use an IGBT Pulse Width Modulation Control method. High frequency current leaks to ground through the stray capacitance in the motor windings, power lines, and amplifier chassis. A GFI designed for use on inverters is protected against such malfunctions. The same situation occurs on power circuits supplied with a leakage protection relay. The protective (earth) ground should be connected to the terminal marked PE.

The minimum capacity for the power for supplying a Fanuc Control is:

Power Supply Model      -5.5             -11              -15             -26              -30
                                       9KVA          17KVA        22KVA       37KVA         44KVA

On the Power Supply Module if the LED indication is (-) the PSM is waiting for the *MCON signal. 

When working on the PSM, if the PIL (Power On Indicator) is on and the ALM (Alarm Indicator) is off but (--) is displayed, MCC is off. If the PIL is on, the ALM is off and 00 is displayed, the Power Supply is ready. When the PIL is off, check the voltage and connection of CX1A. Check FU1 and FU2 of the control PCB. If FU2 is blown, make sure that the control power is connected to CX1A and not mistakenly connected to CX1B. If this connection is correct and FU2 continues to blow, the control PCB is probably defective. Make sure that the 24vdc circuit is not shorted. The PIL indicator is, of course, a 5 volt LED so check the 5vdc supply.

A good indicator of a bad Power Supply Module is that when the incoming AC power is removed the capacitor charged LED goes off instantly instead of bleeding down slowly.

The same number displayed on the LED display of a servo amplifier versus a power supply module can and usually does mean different things. For example, a 9 on the power supply module indicates an overheated heat sink while a 9 on a servo amplifier indicates excessive current in the output circuit.

Older Fanuc controls had a Power Supply (rack) and a separate Input Unit. Newer controls have a Power Unit which is a Power Supply with a built in Input Unit.

No DC Link voltage is generated when the machine is in E-Stop mode

Phase converters are not recommended for Fanuc controls because the power output is usually not suitable. For Fanuc controls the phase to phase voltages must be within 7 percent of each other and the phase angle must be within 12 degrees of 120 degrees.

The main three phase power to a Fanuc power supply is switched on through MCC. The 200 volts for the control functions should be supplied at all times. The control needs this power to turn on and allow MCC to energize.

When working with a Fanuc Power Unit (NC power supply), it is important to remember that the NC power ON/OFF buttons are not like most on/off switches. The power OFF switch is a normally closed switch but it does not feed the ON switch. Both switches are fed from a common point of the power supply but the output of each switch connects to a different point on the power supply. This is why sometimes a Fanuc control can be turned on by the power ON switch but cannot be turned off by the power OFF switch. In these cases the Power Unit is almost always at fault. In the case of the 18 control the connector in question is CP4. Pin A3 of CP4 is the common, pin A2 is POWER OFF and pin A1 is POWER ON.

The information above applies also to the 0 control with the exception that instead of connector CP4 pins A3, A2 and A1 it is CP3 pins 3, 2 and 1.


Generally speaking Canned Cycle for Bolt Hole Pattern is not provided on Fanuc controls. If one is desired, you can make one if you have Custom Macro B.

G65 can be used to call a 9000 program which contains the needed program for the cycle. The format, using 9100 as an example, is:

G65 P9100
Notice the O can be omitted in the program name. This is known as a Simple Call and is much like calling a subprogram with M98. You can specify an argument and number of repetitions.

You can also create a new G Code by using what is called Macro Call using G Code. There is a group of Parameters and program numbers associated with this type. They are:

Program number      Parameter
O9010                      6050
O9011                      6061
O9012                      6052
O9013                      6053
O9014                      6054
O9015                      6055
O9016                      6056
O9017                      6057
O9018                      6058
O9019                      6059

These are pairs and are always associated with one another. When a G Code number is specified in one of the parameters, it's associated program is called when the G Code is executed. For example:

If the value of Parameter 6050 equals 100, when G100 is executed in a program number O9010 will be called. As with the Simple Call above, a number of repetitions from 1 to 9999 as well as an argument specified. Two types of argument are available, either Argument Specification I or II. The type specified is automatically determined by the addresses used. In the case of an 18 control, more can be found about this procedure in section 16 of the Series 16-18 Operators' Manual.

A Macro can also be called with an M Code. It works the same as above using the following program numbers and parameters.

O9020                     6080
O9021                     6081
O9022                     6082
O9023                     6083
O9024                     6084
O9025                     6085
O9026                     6086
O9027                     6087
O9028                     6088
O9029                     6089

To execute Constant Surface Control:
G96 P1 S______;

P1=X axis  P2=Y axis  P3=Z axis  S=Spindle RPM

If P is omitted the NC assumes P0. P0 is the axis assigned in Parameter 41.4 and 41.5.  If the S command is omitted, spindle RPM = the last G96 command.

To cancel Constant Surface:
G97 S______;

The S command here becomes the new spindle speed.

S commands specified with G96 command are assumed to be zero until either M03 or M04 is seen in the program.

When executing G96, the Work Coordinate System must be set so that the center of the rotating axis is zero.

G92 S_____; clamps the speed during G96 to avoid exceeding maximum spindle speed.

For problems with Work Shift and Absolute position, keep in mind G50.

To test for Helical Interpolation operation:

G02 I2. Z-10. F50.;

This should cause the Z axis to move to 10 inches from it's current position as X and Y interpolate a 4 inch circle. If the axes are truly interpolating, the Z axis will reach it's position at the same instant that X and Y reach the end point. To reverse the process:

G03 I2. Z10. F50.;

Remember that G02 and G03 are always specified as incremental commands.

G99 can only be made effective from Auto mode, not MDI.

When using G50 to clamp the spindle speed, specify it in a block after the initial M3 or M4. For example:

M3 S500;
G50 S2000;

To DNC with a Fanuc control, as with other controls, you must have a full wire cable. The cable normally used to load parameters, etc will not work. The pins that are shorted with this configuration are used for flow control.

The buffer of a zero control will only hold a block or two of data at one time. When doing DNC, the control will take in ten characters then have the PC stop sending while these are processed then will request more.

Most machine tool builders number their programs in the 9000 series. These programs come with the machine and are not meant to be edited or downloaded. Some builders will disable manipulation of these programs with parameter 10 bit 4 and you can change this bit in order to access these programs. Other builders will write their software to prevent you from accessing the program no matter what you do. As far as Fanuc controls in general, if you can't display a programs contents on the CRT you cannot transmit it or alter it.

The procedure for loading a program from a PC is:

1. Switch to EDIT mode.
2. Press the PRGRM key.
3. Select the I/O soft key.
4. Select the READ soft key.
    ( LSK should begin flashing in the lower right hand corner)
5. Begin transmission from the PC.

Programs cannot be sent or received while an alarm condition exists.

Programs cannot be received by the control unless the Key is set to a one. This can be checked at Diagnostic 122 Bit 3.

Some G Codes are always active at power up and cannot be changed. For example G98 or G99. G98 is Feed Per Minute. G99 is Feed Per Revolution. If you are working with a lathe it will almost always come up in G99. If you want to run in Feed Per Minute you have to program G98. 

G20 and G21 can be selected for power up by parameter. With G20/G21 the mode you power down in is the mode the control powers up in. To change back and forth manually, command it in MDI.

If a control will not execute G01 on a lathe, make sure it is not in G99. If G99 is active when a G01 is commanded, the spindle must be running or the machine must be in DRY RUN. G99 is Feed/Rev. G98 is Feed/Min. To test this you can command G01 then turn the spindle by hand. Also you can look at the right hand side of the CRT while in MDI/PGM mode and see if G99 is active. Most lathes power up in G99.

When programming in G99 mode, the Feed rate you enter is distance for the axis to move per revolution of the spindle so it should be a very small number such as F.001.

G43 specifies the tool offset in the positive direction.
G44 specifies the tool offset in the negative direction.
If G43 is commanded, the tool offset called must be a negative number or the machine will over travel in the positive direction.

G54 calls up the first Coordinate system which is usually the X,Y, and Z reference points (Machine Home). You can put different values in G55, G56, etc. When one of these are called, these values will set the new coordinate system.

When you program a Fanuc controlled machine to Rigid Tap you must give preparatory commands such as G98 (FEED PER REVOLUTION). This is unnecessary on a Mitsubishi control. Below is a program that will work on a Mitsubishi control.

M29 S400;
G84 G98 X0 Y0 Z-.75 R.1 F.083 ,R1;

You can also try this format:

M03 S400;
M29 S400;
G84 Z-1. R.1 F.083;

Be sure to return the machine to FEED PER INCH.

To search for a point in a program, switch to edit mode, enter the sequence number or T Code etc. that you want to go to and press the cursor down key. You can do the same thing in Auto mode but you can only search for a sequence number. If program restart is enabled you can restart the program after either search by being in Auto mode and pressing Cycle Start.

When trying to program in CAP if you have trouble with alarms like EXCEEDED NUMBER OF PROCESSES or PROCESS NOT FOUND it may be a memory amount or memory allocation problem. Try freeing up some memory to solve problem.

A Macro can also be called with an M Code. It works the same as above using the following program numbers and parameters.

O9020               6080
O9021               6081
O9022               6082
O9023               6083
O9024               6084
O9025               6085
O9026               6086
O9027               6087
O9028               6088
O9029               6089

G05 P01 turns on High Speed Machining, G05 P00 turns it off. While in G05, all commands are considered to be incremental.

Fanuc End

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The information on this and subsequent pages is intended to supplement and reinforce the knowledge of competent machinists and technicians. The authors of this website are in no way lialble for damage or injury resulting from the improper use of the instructions contained herein.