HP 6038A Service Manual

3-192 Note that the test command in no way changes the
programmed state or the output of the power supply.
CAUTION
The TEST? command software contains a bug
which can affect overvoltage protection, if TEST?
is sent with OUT OFF (output disabled), over¬
voltage protection will be disabled until the power
supply receives an RST or CLR command or ac
power is cycled off and back on. To restore over¬
voltage protection after TEST? command, be cer¬
tain to send an RST or CLR command before sen¬
ding the OUT ON command. RSTis recommend¬
ed, because CLR will reset all power supply
parameters to the power-on state; RST resets on¬
ly OVP.
Note that if OVP is tripped, RST or CLR will reset
the OVP circuit in addition to restoring overvoltage
protection.
Overvoltage protection is not affected if the power
supply output has not been disabled for self test
(i.e., if OUT OFF command is not send with
TEST?).
3-193 Model Identification. The power supply model
number can be determined from the controller by sending the
command:
ID?
and addressing the power supply to talk. The response from
the power supply will be either:
ID HP6038A
or
ID HP6038A, OPT100
with the option 100 identification indicating that the power sup¬
ply has a reduced output-power capability.
3-194 ANALOG PROGRAMMING
3-195 The output voltage and/or current of the power sup¬
ply can remotely programmed by an external resistance or
voltage. The power supply Is configured for analog program¬
ming with rear-panel slide switches; the analog programming
signals are connected to rear-panel screw-on terminals.
3-196 For resistance programming, internal CV and CC cur¬
rent sources supply 1.5 mA currents through the program¬
ming resistors to create programming voltages for the power
supply. Resistances of 0 to 4 kilohms program the output from
0 to full scale. A variable resistor can control the output over
its entire range. Or, a variable resistor connected in series and/or
parallel with a fixed resistor can have its control restricted to
a limited portion of the output range. Alternatively, a switch
can be used to select fixed values of programming resistance
to obtain a set of discrete voltages or currents.
NOTE
The switching configuration used may require
make-before-break contacts to avoid producing
the output voltage transients caused by momen¬
tarily opening the programming terminals.
3-197 To maintain the temperature and stability specifica¬
tions of the power supply, any resistors used for programming
must be stable, low-noise resistors with a temperature coeffi¬
cient of less than 25ppm per °C and a power rating of at least %
watt.
3-198 Both voltage and current outputs can also be con¬
trolled by a voltage source. A voltage of 0 to 5 volts programs
the output from zero to full scale. Voltage sources of more than
5 volts can be scaled down to the proper range.
3-199 Setting the power supply for analog programming of
voltage and/or current disables digital programming (front-panel
or HP-IB) for that parameter.
3-200 The following paragraphs discuss in greater detail the
methods of remotely programming the output voltage or
current using either a resistance or voltage input. Whichever
method is used, the wires connecting the programming device
must be shielded to reduce noise pickup. The outer shield of
the cable should not be used as a conductor, and should be
connected to ground at one end only.
3-201 Refer to Table 3-4 for mode-switch settings for
voltage or resistance programming.
3-202 Although the following setup drawings (Figure 3-9
through 3-13) show the supply strapped for local sensing, analog
programming and remote voltage sensing do not interact and
may be used simultaneously.
3-203 Constant Voltage Output, Resistance Control.
The setup shown in Figure 3-9 allows the output voltage to be
varied by using an external resistor to program the power sup¬
ply. A programming resistor variable from 0 to 4000 ohms pro¬
duces a proportional output voltage from zero to full scale. Note
that fixed resistors may be connected in series and/or parallel
with the variable programming resistor to set lower and/or up¬
per output voltage limits. The resultant programming resistance
is the sum of the series/parallel resistor combination, and must
be between 0 and 4000 ohms. For example, a 2000 ohm resistor
connected In series with the variable programming resistor will
set the lower limit for output voltage at one-half full scale.
NOTE
If the programming terminals (VP to P)
become open circuited during resistance pro¬
gramming, the output voltage will tend to rise
above rating. The supply will not be damaged if
this occurs, but the overvoltage trip point should
be properly adjusted to protect the user's load.
3-25

HP 6038A Specifications

General

Brand	HP
Model	6038A
Category	Inverter
Language	English