BNC PCO-6131 User manual

PCO-6131
Laser Diode Driver Module
Operating Manual

Berkeley Nucleonics Corporation
2955 Kerner Blvd., San Rafael, CA 94901 ° Tel [phone] ° Fax [phone] ° ww.berkeleynucleonics.com

Berkeley Nucleonics Corporation
2955 Kerner Blvd., San Rafael, CA 94901 ° Tel [phone] ° Fax [phone] ° ww.berkeleynucleonics.com
TABLE OF CONTENTS
1.0 Safety..........................................................................................................0
2.0 Overview.....................................................................................................1
3.0 System Requirements.................................................................................2
4.0 Connector Pin-Outs And User Adjustments................................................2
5.0 Operating Instructions.................................................................................5
5.1 Output Stripline .................................................................................5
5.2 Load Interconnection.........................................................................5
5.3 Gate Input .........................................................................................6
5.4 Enable Input ......................................................................................6
5.5 Output Current Setpoint Monitor .......................................................6
5.6 Internal and External Current Setpoint ..............................................7
5.7 Leading Edge Risetime Control Potentiometer .................................7
5.8 Indicator LEDs...................................................................................7
5.9 +24VDC Input....................................................................................8
5.10 Power-Up Procedures.....................................................................8
5.11 Power-Down Procedures ................................................................9
6.0 Laser Diode Interconnection Inductance.....................................................10
7.0 Troubleshooting ..........................................................................................15
7.1 Troubleshooting Procedures .............................................................16
7.2 Factory Service .................................................................................16
8.0 Warranty .....................................................................................................17

1.0 Safety
The high-power nature of this device dictates the use of caution when operating or
servicing this equipment. OBSERVE ALL SAFETY PRECAUTIONS LISTED
BELOW. FAILURE TO DO SO COULD RESULT IN INJURY OR DEATH.
Precautions:
1. The Laser Diode Driver should be serviced only by personnel experienced
in high power pulsed power systems.
2. Service personnel should be instructed to observe all safety precautions
as stated in the operating instructions, and those safety precautions standard to
the high voltage pulsed power community. Failure to do so could result in serious
injury.
3. Do not handle the load or terminations, or remove the input or output
cables, while the driver is in operation. Ensure that the 24 VDC power supply has
fully discharged before handling the load. Failure to observe these precautions can
result in potential electric shock to personnel, arcing, and damage to the
connectors and system.
4. The Laser Diode Driver contains reference planes which are elevated to
the potential of the output pulse. Extreme caution should be exercised when
servicing the equipment.
5. The Laser Diode Driver contains electrolytic capacitors. Do not reverse the
polarity of the input DC power supply, and do not exceed the maximum ratings for
the support power supplies. Doing so may result in damage to the capacitors or to
the driver, or personal injury due to venting of the capacitors.
6. Pulsed power systems are capable of random triggering via transients and
therefore when the driver is turned on, or high voltage is present in the module,
assume it is possible to get a pulse on the output stripline.
Berkeley Nucleonics Corporation (BNC) provides information on its products and
associated hazards, but it assumes no responsibility for the after-sale operation
and safety practices.

Berkeley Nucleonics Corporation
2955 Kerner Blvd., San Rafael, CA 94901 ° Tel [phone] ° Fax [phone] ° www.berkeleynucleonics.com
2.0 Overview
The PCO-6131 is a compact, OEM-style high power pulsed current source
designed to drive diode lasers, bars and arrays in pulsed, QCW or CW modes. It
delivers output current variable from 1 A to 125 A, pulse widths variable from <100
ns to DC, and pulse repetition frequencies variable from single-shot to 500 KHz at
duty cycles up to 100%.
The PCO-6131 is based on a hysteretic, average current, switch-mode regulator.
This type of regulator is a variable frequency, variable pulse width design which
maintains current in an energy storage inductor between a minimum and
maximum level. The ripple is limited to the minimum and maximum current
determined by the hysteretic controller. The controller turns on to charge the
energy storage inductor when the current drops to the lower limit and turns off
when the current reaches the upper limit and repeats this operation as necessary
to maintain the proper current. The time for these operations will vary dependent
on the load voltage and the input voltage, therefore the pulse width of the
controller will change as necessary to charge the inductor and the period will
change dependent on the rate at which the inductor discharges. The relationship
for this operation represented by V = L di/dt. When the output is shorted such as
when no pulse is being outputted, the voltage applied to the inductor is 24 Volts.
This results in a very fast increase in current so very short on times are necessary.
When the controller switches off then a very small voltage is across the inductor so
the current decays very slowly and therefore the off time is quite large. All this
reverses when the output is connected to a load. When the load is near the
maximum V, the time to charge the inductor is very large but the decay time is
very short. The advantage of this controller is that the current is controlled to an
upper and lower limit regardless of the pulse width. It can generate short or long
pulses and performs as a current source.
The current regulator is started when the TTL "enable" line is taken high and runs
as long as the enable is high. This happens when the control gate is taken high
and will continue until the gate control is taken low. It will take a finite time for the
current source to charge to the proper current (i.e., a ramp-up time), after which a
pulse can be generated. The use of the hysteretic regulator provides a large input
range and high efficiency.
The current source is combined with a crowbar (shorting switch). The shunting
crowbar switch shorts the output of the regulator until output current is needed.
The pulse is generated by opening the shunt switch for the length of the input
pulse. A pulse is generated when the control gate is high, the shunt switch is
opened for the length of the input control gate, forcing the current to flow through
the laser diode load. The pulse rise and fall times are then limited only by the
stray/parasitic capacitance and inductance of the shunting switch and output
leads.

Berkeley Nucleonics Corporation
2955 Kerner Blvd., San Rafael, CA 94901 ° Tel [phone] ° Fax [phone] ° www.berkeleynucleonics.com
The control signal for the current source is called the “enable” and has thresholds
compatible with TTL logic. The “gate” control has thresholds compatible with
CMOS (CMOS is complementary metal oxide semiconductor) logic.
Very little power is dissipated in the driver until it is enabled. When enabled, at 125
A maximum output approximately 75 W is continuously dissipated in the driver to
maintain the current in the energy storage inductor (see note #1 under
specifications). The load power is added to this continuous power and the pulse
rate will further increase power consumption.
This architecture provides a high-performance driver in a small form factor, with
high operating efficiency and low stored energy. At 125 A output current, the
stored energy in the inductor of the driver is approximately 0.5 s, dramatically
lower than the stored energy in comparable linear current sources.
The PCO-6131 features a user-adjustable variable rise time control. This
innovative feature allows the user to adjust the rise time within a range of <30 ns
to >2.5 µs by means of a PCB-mounted potentiometer, to optimize the driver’s rise
time for the user’s application. In applications in which the laser diode or
interconnection between the driver and the diode is somewhat inductive, the fast
rise time of the PCO-6131 may induce ringing on the leading edge of the pulse.
The rise time may be slowed down using the variable rise time control to minimize
or eliminate this ringing.
3.0 System Requirements
The PCO-6131 requires user-supplied +24 VDC support power, a CMOS (+5 V)
gate signal, and a TTL-level enable/disable signal. The high current output is
derived from the +24 VDC DC input. The output pulse width and frequency are
controlled by the gate signal. The output current amplitude is controlled by a PCB-
mount potentiometer. An optional current monitor, the PCA-9155, output may be
viewed with an oscilloscope, providing a straight-forward means to observe the
diode current waveform in real-time.
To protect the laser diode and the driver, circuitry is incorporated into the driver
that disables the output if the +24 VDC support power drops below 18 V. Clamp
diodes are incorporated into the output network to protect the laser diode against
reverse voltage conditions. The heat sink is monitored for over temperature by a
thermistor. The output cable connection is monitored by a magnetic reed switch.
When the reed switch is not activated, the pulse will be disabled.
Open circuit protection is provided by a 60 Ampere diode connected from the
output to the 24 VDC supply. The user should be aware that even if the output is
an open-circuit, the output current (determined by the current set-point) will flow
into this protection diode. Therefore, care should be taken to ensure the load is
properly connected to the PCO-6131 before pulsing.
4.0 Connector Pinouts And User Adjustments
The support power and control signals are on a 14 pin FCI Connector header, part
number 66429-055. This header mates with an FCI housing, part number 65846-

Berkeley Nucleonics Corporation
2955 Kerner Blvd., San Rafael, CA 94901 ° Tel [phone] ° Fax [phone] ° www.berkeleynucleonics.com
008 or equivalent. The sockets for use with this housing are FCI Connector part
number 48236-000 or equivalent. A housing connector and sockets are included
with the PCO-6131. The pin-out of this connector follows:
Pin Number
Description
2
NC
4
Current Setpoint Input
6
Output Current Setpoint Monitor, Scaling is 20 mV/A
into High Impedance
*
8
Pulse Input (Gate), +5 V CMOS
10
Enable/Disable, TTL High = Enabled
12
+5 VDC
14
NC
Odd Pins
Ground
* The setpoint monitor provides a scaled output of the current in the inductor. This
output can be used to set the output current amplitude prior to generating an
output pulse.
The indicator LEDs are only to show function and are not tolerance controlled.
The output pulse current may be monitor using the optional external current
monitor board (PCA-9155) via the cable. Scaling is 1000 A/V into 50 Ohms. The
output of this CVR has a 51.1 Ohms resistor in series to provide a 50 Ohm
termination to the coax cable. When properly terminated at the Oscilloscope with
50 Ohms, the monitor will provide an accurate representation of the current
pulses. The shield of the coax is connected to the negative output. The CVR is in
the negative lead.
The output is provided on a high current PCB-mount DSUB connector Amphenol
#77TW-C-8W8-S-MP3V-4R or Connector #3008W8SXX57A30X. A magnet is
mounting on the housing to activate the interlock reed switch.
The driver is provided with a mating output connector Amphenol # 717TW-C-8W8-
P-P3Y or Connector #3008W8PXX51A10X and stripline. Pins 2, 4, 6 & 8 are the
positive pulse output, and pins 1, 3, 5 & 7 are the return.
The +24 VDC input are screw terminals located on the main circuit board.
Connectors E1 and E4 are +24 VDC. E2 and E3 are ground.

Berkeley Nucleonics Corporation
2955 Kerner Blvd., San Rafael, CA 94901 ° Tel [phone] ° Fax [phone] ° www.berkeleynucleonics.com
These connectors are shown in the photo below:
Figure 1: Connectors J2, E1, E2, E3 and E4 Locations
The Output current is set by the Current Set potentiometer, located on the edge of
the smaller logic circuit board. The current may also be set by a remote analog
input. See Section 5.0 for more details.
The variable rise time is adjusted by the Rise Time potentiometer, located on the
edge of the smaller logic circuit board.
All potentiometers can be adjusted while the unit is operating. A suitable insulated
adjustment tool should be used. Actual operation is usually necessary so that the
correct waveforms can be made and adjusted to suit the user’s needs.
The photo below shows the location of the control potentiometers, jumpers, and
indicator LEDs:
E1 AND E4
E2 AND E3
J2 PIN1

Berkeley Nucleonics Corporation
2955 Kerner Blvd., San Rafael, CA 94901 ° Tel [phone] ° Fax [phone] ° www.berkeleynucleonics.com
Figure 2: Control Potentiometers, Jumper and LED Locations
5.0 Operating Instructions
WARNING
1. Do not remove the input or output cables while the driver is in operation. Do
not operate the driver without an appropriate load connected to the output
stripline. Failure to observe these precautions can result in potential electric
shock to personnel, arcing, and damage to the connectors and system.
2. Pulsed power systems are capable of random triggering via transients and
therefore when the pulse generator is turned on, or high voltage is present in
the chassis, assume it is possible to get a pulse on the output connector.
5.1 Output Stripline
The PCO-6131 is provided with a low impedance output stripline cable. The laser
diode should always be connected to the driver using this stripline cable. Wire or
twisted pair are too inductive and may seriously degrade the fidelity of the output
current waveform.
5.2 Load Interconnection
The output is provided on a high current PCB-mount DSUB connector Amphenol
#77TW-C-8W8-S-MP3V-4R or Connector #3008W8SXX57A30X, terminated with
a low-inductance stripline cable. Pins 2, 4, 6 & 8 of the connector are the positive
pulse output, and pins 1, 3, 5 & 7 are the return.
LEDS
POTENTIOMETERS
AND JUMPER

Berkeley Nucleonics Corporation
2955 Kerner Blvd., San Rafael, CA 94901 ° Tel [phone] ° Fax [phone] ° www.berkeleynucleonics.com
The output stripline is marked with a + and -. The “+” side is the positive output
pulse, and the “-“ side of the stripline is the return. The laser diode anodes connect
to the “+” side of the stripline, and the laser diode cathode connects to the “-“ side.
A magnet is mounted to the housing to activate the magnetic reed switch.
The laser diode should be connected directly to the end of the stripline. If wire
interconnections are needed between the end of the stripline and the diode, they
should be kept as short as possible, preferably no more than 2” (5 cm) to minimize
interconnection inductance. Excessive inductance in the interconnections or laser
diode package may lead to ringing on the leading edge of the pulse waveform.
This ringing may be reduced or eliminated by lengthening the pulse rise time using
the variable rise time feature.
5.3 Gate Input
An input gate of +5 V ±1 V (CMOS) is required to gate on the PCO-6131.
Departure from these values can result in a loss of performance. This trigger
requirement is met by any high-quality low voltage pulse generator.
The gate signal should be connected to J2-8 using a 50 Ωcoaxial cable. The
shield of the coaxial cable should be connected to any one of the ground pins of
connector J2. To improve pulse fidelity, all connections should be as short as
possible.
The output pulse’s width and frequency follow the width and frequency of the input
gate. To generate a CW output, the gate should be held high.
5.4 Enable Input
The “enable” signal (J2-10) is used to enable and disable the output of the PCO-
6131. This input must be pulled TTL “High” to enable the driver. This input can be
connected to an interlock or key switch in the user’s system or may be controlled
by the system’s control computer.
When the driver is enabled but not pulsing, it dissipates a fixed amount of power
(see Section 5.5 below). Therefore, for optimum efficiency and minimum power
consumption, the driver should be disabled when not in use.
5.5 Output Current Setpoint Monitor
The output current setpoint monitor (J2 Pin 6) can be used to set the output
current flowing in the inductor prior to generating an output pulse. This allows the
user to set the current that will be applied to the diode, without applying power to
the diode. To set the current using the setpoint monitor, the PCO-6131 must be
enabled, while the gate input is held low.

Berkeley Nucleonics Corporation
2955 Kerner Blvd., San Rafael, CA 94901 ° Tel [phone] ° Fax [phone] ° www.berkeleynucleonics.com
5.6 Internal and External Current Setpoint
In internal mode, the potentiometer labeled Current Set controls the output current
amplitude. 0 A is full counterclockwise. The output current setpoint monitor may be
used to set the output current without applying a pulse to the laser diode.
The external current setpoint (J2 Pin 4) allows the user to apply an external
voltage to the potentiometer circuit. The on-board potentiometer then can be used
as a range scaling potentiometer. To use this feature, the Current Set
External/Local jumper must be set to the External setting (see Figure 2). If the
jumper is set to the Local setting, this input is not used.
For example, to use 0-10 V input and scale the output accordingly, the
potentiometer may be adjusted to correlate the maximum output current to 10 V
maximum input. In the local mode with the unit enabled and the gate input held
low, set the potentiometer to 0 A output, and then change the jumper to External
Mode. Apply the maximum input voltage desired to the Current Setpoint Input (i.e.,
10 V). Then slowly adjust the current setpoint potentiometer until the desired
output current is obtained on the Output Set Point Monitor. DO NOT OPERATE
OR PULSE THE UNIT INTO AN OPEN OR HIGH IMPEDANCE LOAD WHILE
MAKING THIS ADJUSTMENT.The output current may be monitored using the
internal monitor on J2 pin 6. This allows the user to scale the output current to any
analog voltage program up to 20 V.
5.7 Leading Edge Risetime Control Potentiometer
The PCO-6131 features a user-adjustable variable rise time control. This feature
allows the user to adjust the rise time within a range of <30 ns to >2.5 µs by
means of the PCB-mounted potentiometer (see Figure 2), to optimize the driver’s
rise time for the user’s application. In applications in which the laser diode or
interconnection between the driver and the diode is somewhat inductive, the fast
rise time of the PCO-6131 may induce ringing on the leading edge of the pulse.
The rise time may be slowed down using the variable rise time control to minimize
or eliminate this ringing.
Full counterclockwise is the fastest rise time, and full clockwise is the longest rise
time. Please note that this feature does not affect the pulse fall time.
5.8 Indicator LEDs
Several LEDs on the driver logic board may be used for verification of functionality
and for troubleshooting. The LEDs and their function are listed below:

Berkeley Nucleonics Corporation
2955 Kerner Blvd., San Rafael, CA 94901 ° Tel [phone] ° Fax [phone] ° www.berkeleynucleonics.com
LED
FUNCTION
LED1
Enable Indicator. If the driver is enabled, the LED will be
illuminated. If it is disabled, the LED will be off.
LED2
+5 VDC Monitor. If the +5 VDC on-board regulator is
functioning correctly, this LED will be illuminated.
LED3
+15 VDC Monitor. If the +15 VDC on-board regulator is
functioning correctly, this LED will be illuminated.
LED4
-15 VDC Monitor. If the –15 VDC on-board regulator is
functioning correctly, this LED will be illuminated.
LED5
+24 VDC Monitor. Indicates +24 VDC is applied to the
driver.
D27
Interlock Fault – indicates the interlock reed switch is
open.
D28
Over Temperature Fault – indicates maximum heat sink
temperature has been exceeded.
D29
Under Voltage Fault – indicates input voltage is below 18
Volts.
5.9 +24VDC Input
The +24 VDC input provides the power for the output current. This voltage may be in
the range of +20 V to +28 V. It may be unregulated if it does not vary below 20 V or
above 28 V.
At 125 A output, the driver dissipates ~75 W when enabled but not pulsing.
Efficiency is therefore the ratio of output power to the input power or η = output
power / (idle power + output power). The idle power consumption varies non-linearly
with output current and can be approximated by the formula P=I2x 0.005 where I is
the output current. For example, at 75 A output current, the idle power consumption
is 752x 0.005 = 28 W.
The +24 VDC support power should be sized for the average output power (Power x
Duty Cycle) plus the idle power consumption as defined above, and an additional
20% for pulse switching losses.
5.10 Power-Up Procedures
1. The unit should be powered up using the following procedures:
2. Before connecting the input pulse generator to the PCO-6131 pulser, set up
the pulse generator output to deliver a CMOS level pulse with a repetition rate
and pulse width appropriate for the laser diode being driven. Before connecting
input connector J2 to the driver, turn off or disable the output of the pulse
generator.
3. Connect the input connector J2 prior to applying +24 VDC support power.
4. Connect the +24 VDC support power to connectors E1, E2, E3 and E4.

Berkeley Nucleonics Corporation
2955 Kerner Blvd., San Rafael, CA 94901 ° Tel [phone] ° Fax [phone] ° www.berkeleynucleonics.com
5. Connect the laser diode to the output connector using the stripline.
6. Apply +24 VDC (±4 V) power to the module.
7. To set the output current prior to enabling the output, follow the procedure in
steps 8-11 below.
8. Ensure that the input gate signal is low (i.e., the input pulse generator is turned
off or is disabled).
9. Enable the PCO-6131 by pulling the enable input HIGH
10.Monitoring the voltage of the Output Current Setpoint Monitor (J2 Pin 6) with an
oscilloscope or Digital Voltmeter (DVM), set the output voltage to correspond to
the appropriate output current by adjusting the Current Set potentiometer. See
Section 5.7 for remote current set instructions.
11.When the current is set to the appropriate level, disable the output by pulling
the enable input LOW.
12.If the output current has not been set using the Output Current Setpoint
Monitor and the procedure detailed in steps 8-11 above, turn the Current Set
potentiometer fully counterclockwise (to set the output current to zero).
13.Enable the PCO-6131 by pulling the enable input HIGH
14.Turn on or enable the input gate signal.
15.If the output current has not been preset, slowly turn up the output current by
the Current Set potentiometer clockwise. The PCO-6131 should produce an
output pulse, with a pulse width and pulse recurrence frequency following that
of the incoming gate. The output pulse current may be monitor using the
optional PCA-9155. Scaling is 1000 A/V into 50 Ohms.
16.If there is no output from the PCO-6131, or the output is severely distorted,
disable the output, and turn OFF the +24 VDC power supply. Leave the PCO-
6131 connected to the DC input support power without voltage applied and
with all connectors in place for approximately one minute to bleed off the stored
energy, then disconnect the DC power to the unit and refer to the
Troubleshooting Section of this manual.
5.11 Power-Down Procedures
1. Disable the output.
2. Turn off the +24 VDC power supply.

Berkeley Nucleonics Corporation
2955 Kerner Blvd., San Rafael, CA 94901 ° Tel [phone] ° Fax [phone] ° www.berkeleynucleonics.com
3. Leave the PCO-6131 connected to the +24 VDC input with the voltage turned
off and with all connectors in place for approximately one minute to bleed off
the stored energy.
4. Disconnect the DC support power to the unit.
6.0 Laser Diode Interconnection Inductance
Application of the PCO-6131 requires an attention to detail to prevent problems
with inductance in the leads and load. BNC has tested the PCO-6131 with laser
diodes to determine how best to apply high current pulses to laser diodes, and the
result of this investigation is presented below.
A stripline is very integral to obtaining good fidelity of current pulses. The strip line
shown in the figures in this note is the stripline supplied with the PCO-6131 and is
available from BNC.
When a stripline is used and connected directly to the laser diode, the fall time was
in the range of 500 ns. When the laser diode was connected to the stripline with
about 6 inches of wire, the fall time degraded to about 6 microseconds. Inductance
negatively affects fall time, and the performance seen with these two
interconnection topologies is consistent with the inductance introduced into the
circuit by the wire interconnections.
For all tests, the laser diode was driven at approximately 50 Amperes. A diode
forward voltage of about 2.4 V was measured, confirming that the laser diode was
correctly wired into the circuit. The repetition frequency was limited to a few Hertz,
eliminating the need to heatsink the laser diode.

Berkeley Nucleonics Corporation
2955 Kerner Blvd., San Rafael, CA 94901 ° Tel [phone] ° Fax [phone] ° www.berkeleynucleonics.com
Figure 3 - Test Setup
Figure 4 and 5 show how the output stripline was connected to the laser diode for
the first set of tests. In Figure 4, the stripline was intentionally separated to show
connections. Normally it is best if the stripline conductors are closely coupled to
each other to minimize inductance.
Figure 4 - Stripline Connection to Laser Diode

Berkeley Nucleonics Corporation
2955 Kerner Blvd., San Rafael, CA 94901 ° Tel [phone] ° Fax [phone] ° www.berkeleynucleonics.com
Figure 5 - Stripline Connection to Laser Diode
Using this interconnection, at 50 A output the following electrical performance was
measured. For all photos, the top trace is the input gate to the PCO-6131, and the
bottom trace is the output current pulse measured with the PCO-6131’s current
monitor.
Figure 6 - 1 Microsecond Pulse Width
545 ns Fall Time, 55 ns Rise Time Using a Stripline

Berkeley Nucleonics Corporation
2955 Kerner Blvd., San Rafael, CA 94901 ° Tel [phone] ° Fax [phone] ° www.berkeleynucleonics.com
Figure 7 - 5 Microsecond Pulse Width
560 ns Fall Time, 54 ns Rise Time Using a Stripline
Figure 8 - 10 Microsecond Pulse Width
550 ns Fall Time, 67 ns Rise Time Using a Stripline
We then connected the laser diode to the PCO-6131 output stripline using
approximately 6 inches of wire. Ring lugs were used to attach the wires to the
laser diode, and the other ends of the wires were soldered to the ends of the
striplines. This interconnection is shown in Figure 9.

Berkeley Nucleonics Corporation
2955 Kerner Blvd., San Rafael, CA 94901 ° Tel [phone] ° Fax [phone] ° www.berkeleynucleonics.com
Figure 9 - Laser Diode Connected Using
Approximately 6 Inches of Wire
Using this interconnection, at 50 A output the following electrical performance was
measured. For all photos, the top trace is the input gate to the PCO-6131, and the
bottom trace is the output current pulse measured with the PCO-6131’s current
monitor.
Figure 10 - 1 Microsecond Pulse Width – Wire Interconnection
3.8 Microsecond Fall Time, 438 ns Rise Time

Berkeley Nucleonics Corporation
2955 Kerner Blvd., San Rafael, CA 94901 ° Tel [phone] ° Fax [phone] ° www.berkeleynucleonics.com
Figure 12 - 5 Microsecond Pulse Width – Wire Interconnection
4.3 Microsecond Fall Time, 454 ns Rise Time
As can be seen from the data above, even the inductance of 6 inches of wire in
the connection between the stripline and the laser diode can result in a 5X to 8X
degradation in the rise time and fall time.
7.0 Troubleshooting
WARNING
The module contains capacitors that are used as energy storage elements. When
charged, these capacitors contain more than 7 joules of stored energy. This is
enough energy to cause injury. Assure that the +24 VDC power is disconnected
from the pulser, and that the capacitor bank is fully discharged before any repairs
or adjustments are attempted. Verify with a voltmeter that all circuits are de-
energized before servicing. Dangerous voltages, floating ground planes and
energy storage exist at several locations in the module. Touching connections or
components could result in serious injury.

Berkeley Nucleonics Corporation
2955 Kerner Blvd., San Rafael, CA 94901 ° Tel [phone] ° Fax [phone] ° www.berkeleynucleonics.com
7.1 Troubleshooting Procedures
The table below summarizes potential problems and their solutions. If these
recommendations do not resolve the problem, BNC customer service can be
contacted for further assistance.
SYMPTOM
SOLUTIONS
No output pulse
•No input gate
•Input gate voltage too low
•Input gate pulse width too short. Increase
width
•Input gate frequency too high. Reduce
frequency
•No +24 VDC input voltage. Check input
supply and connections
•Enable circuit not satisfied
•Output not connected correctly. Check all
cables and connections
•Pulser is damaged. Contact BNC customer
service
7.2 Factory Service
If the procedures above fail to resolve an operational problem, please contact the
factory for further assistance:
Berkeley Nucleonics Corporation.
2955 Kerner Blvd. #D
San Rafael, CA 94901 USA
[phone]
[e-mail]
www.berkeleynucleonics.com/rma-forms