225 Series User’s Manual
4
118120-001-Rev. A
2.4
VOLTAGE CONTROL
The 225 Series power supply has three modes of
controlling the high voltage outputs available to the user.
Set the PROGRAM CONTROL switch (S101) on the
rear panel to LOCAL/IEEE-488 for front panel control
or for remote IEEE-488 control. For remote analog
control, set the switch to the REMOTE ANALOG
position. The high voltage output can then be remotely
programmed either from an external voltage source or by
using an external potentiometer. When S101 is in the
REMOTE ANALOG position, the front panel controls
will have no effect on the output voltage setting.
At all times, regardless of the position of the rear panel
PROGRAM CONTROL switch or the GPIB status
(Local, Remote or Local Lockout), the user may enable
or disable the high voltage output by switching the HV
ENABLE switch on the front panel. In addition, the
voltage and current monitors are always active. Thus,
even when the PROGRAM CONTROL switch is set to
REMOTE ANALOG control position or the GPIB has
brought the unit to remote or local lockout, the front
panel, the GPIB and the remote analog monitors continue
to make voltage and current readings available.
2.5
POLARITY REVERSAL
The front panel LED display will indicate which polarity
the unit is set for. The display illuminates even if there is
no high voltage output.
CAUTION – LINE INPUT POWER MUST BE
TURNED OFF AND THE HIGH VOLTAGE
SHOULD BE DISCHARGED FULLY BEFORE
PROCEEDING TO REVERSE THE POLARITY.
2.5.1
POLARITY REVERSAL 500V TO 5kV
OUTPUT MODELS
The screwdriver-rotatable POLARITY SELECTOR
switch (S3) is accessible at the rear panel of the unit.
Rotate as required for the desired polarity.
2.5.2
POLARITY REVERSAL 10kV TO 50kV
OUTPUT MODELS
The polarity is reversible by means of an internal polarity
module, which is easily accessible upon removal of the
top cover. Polarity is reversed by removing two
diagonally opposed Philips head screws, lifting up on the
module, rotating it 180°, and then reinserting it. A safety
interlock automatically ensures that the high voltage
cannot be turned on unless this module is fully seated
and installed in one polarity position or the other.
A remote polarity indication is provided at J107
(PROGRAMMING/MONITOR) connector jack located
on the rear panel of the unit (see section 5.3).
SECTION III: GPIB OPERATION
CAUTION! THIS UNIT CAN STORE HAZARDOUS
VOLTAGE. COMPLETELY DISCHARGE HIGH
VOLTAGE AT REAR PANEL GROUND
TERMINAL BEFORE ATTEMPTING REMOVAL
OF THE HIGH VOLTAGE CABLE
3.1
PROGRAM CONTROL SWITCH
Before a unit of the 225 Series may be used in a GPIB
system, the user must set the power supply’s rear panel
PROGRAM CONTROL switch (S101) in the
LOCAL/IEEE-488 position.
3.2
GPIB ADDRESS SWITCH
An eight-position DIPswitch (S9) is located on the rear
panel of the unit. Every instrument on a GPIB system
must have a unique bus address in the range 0 to 30,
inclusive. A unit’s address is set using S9 switch
positions A4 through A0. A4 is the most significant
address bit and A0 the least significant bit. Bit A5 of the
address switch will enable or disable the power-on
Service Request. Bit A6 controls whether the power
supply will terminate its output character strings with our
without a carriage return and a linefeed. Bit A7 must
remain in the logic 0 state. Figure 3.1 shows the switch
orientation and bit designations.
S9 is read ONLY at power-on. Therefore, when any of
the above is to be changed, the unit must first be turned
off, the required changes made and then the unit must be
turned back on.
A7 Set
to
0
A6 Line
Terminators:
1 Carriage
Return & Linefeed (CR/LF) (*)
0
No Line
Terminators
A5 Service
Request: 1 Service
Request sent at power-on
0
No Service
Request is
sent at
power-on
A4 GPIB
Address
MSB
A3 GPIB
Address
Bit
(*) Line terminators are or are not appended to
the
A2
GPIB Address Bit returned strings
described in sections 3.4.8 and 3.4.9 based on
the settings of A6
A2 GPIB
Address
Bit
