685 Series
ComboPak
User’s Manua
l · Page 19
Grounding and Wiring Considerations
The
ComboPak
electrically isolates the control circuitry from Earth Ground,
allowing the laser anode or laser cathode to be connected to earth ground and
still allow proper operation.
However, care needs to be taken when connecting the
ComboPak
to your
module, especially when using the Control I/O Interface, to prevent damage to
the
ComboPak
or to your laser module.
Always follow these rules when connecting to the
ComboPak
:
1.
Never have more than one earth ground connection to any Laser, TEC,
or Control I/O pin.
2.
Never connect any Control I/O pin to any Laser or TEC output pin.
3.
Never connect TE+ or TE
–
to anything but the TEC module.
4.
Never connect or Sensor
–
to anything but the thermistor
sensor.
5.
Never connect Fan+ or Fan
–
to anything but the fan.
The most common potential wiring issue is the first item, where the laser has the
anode or cathode connected to earth ground and one of the signals on the
Control I/O is also earth grounded (such as the modulation source or the digital
I/O pins). This causes a ground path through the laser module that, at a
minimum, can disrupt proper operation of the
ComboPak
, or, at worst, damage
your laser. In situations like this, you must break one of the ground paths, either
by isolating the laser module from earth ground, or by breaking the ground path
on the instrument connected to the Control I/O interface.
The second item typically happens along with the first item, where the ground
for the Control I/O signals is earth ground and the laser is also earth grounded.
CAUTION
Excluding the AC and USB ground connection, making
more than one earth ground connection to any signal or
control pin may cause damage to the instrument or your
device.
CAUTION
Never connect the Control ground (pin 8) to the laser or
TEC output pins, or damage to the instrument or your
device may result.
