Section Iii Operating Instructions; Controls And Indicators - HP 6235A Operating And Service Manual

SECTION III
OPERATING INSTRUCTIONS
3-1 INTRODUCTION
3-2 This section describes the operating controls and
indicators, turn-on checkout procedures, and other opera¬
ting considerations for the Model 6235A Triple Output
Power Supply.
WARNING
Before the instrument is switched on, all protective
earth terminals, extension cords, auto-transformers
and devices connected to it should be connected
to a protective earth grounded socket Any inter¬
ruption of the protective earth grounding will cause
a potential shock hazard that could result in
personal injury.
Only fuses with the required rated current and
specified type should be used. Do not use repaired
fuses or short circuited fuseholders. To do so
could cause a shock or fire hazard.
3-3 CONTROLS AND INDICATORS
3-4 Line Switch
3-5 The LINE pushbutton switch (item (?) , Figure
3-1) is pushed-in to turn the supply ON and released (out
position) to turn the supply OFF. A simulated (non-electri¬
cal) ON indicator (within the pushbutton) "lights" when the
button is pushed-in whether or not power is applied to the
unit.
3-6 Voltage and Current Metering
3-7 Four meter select pushbutton switches (items
(5)
and (3) ) permit the output voltage or current of any one
supply (+6V, +1 8V, or —18V) to be monitored on the
VOLTS/AMPS meter (?) . The V/A pushbutton (2)
selects either voltage (out position) or current (in position).
The +6, +18, and -18 output select pushbuttons (s)
connect the desired output to the metering circuit when the
applicable button is pushed-in. The three output select
pushbuttons are mechanically interlocked so that only one
can be pushed-in at a time. The voltmeter and ammeter
ranges selected by the +6, +18, and -18 pushbuttons are
listed below. The shaded areas on the meter scales indicate
the amount of output voltage or current that may be avail¬
able in excess of the normal rating.
OUTPUT METER RANGES
VOLTS AMPS
+6V 0-7
0
-1.2
+18V
0-21
0-0.24
-18V
0-21
0-0.24
3-8 Voltage Controls
3-9 The+6 VOLTAGE control (5) sets the output
voltage level of the +6V supply and the ±18 control (6)
sets the output voltage levels of the dual tracking ±1 8V sup¬
plies. Precise tracking of the +18V and —18V outputs is
achieved by controlling the positive output and using it as a
reference voltage for the negative supply. The TRACK
VOLTAGE control (?) sets the ratio between the —18V
and +18V output voltages. Once the ratio is set, the +18
VOLTAGE control will control both outputs with a constant
ratio maintained between the two outputs. The voltage
controls (cermet potentiometers) have infinite resolution;
thus, the resolution obtained depends only upon the user's
care in setting the controls. Greater accuracy in setting the
controls can be achieved by using a DVM to measure the
outputs.
3-10 TURN-ON CHECKOUT PROCEDURES
3-11 The following steps describe the use of the Mode!
6235A front panel controls and indicators illustrated in
Figure 3-1 and serve as a brief check that the supply is opera¬
tional. Follow this checkout procedure or the more detailed
performance test of paragraph 5-6 when the instrument is
received and before it is connected to any load equipment.
Proceed to the more detailed performance test beginning in
paragraph 5-6 if any difficulties are encountered.
—— CAUTION-
Before the supply is switched on, check
the label on the heat sink to make certain that
the supply's line voltage option agrees with the
line voltage to be used. The supply will be damaged
if its internal switch is set for a 120Vac input and
240 Vac input power is applied.
a. Connect line cord to power source and push
LINE switch (?) in.
b. Set meter select switches (2) , (3) to monitor
3-1