Atec Tektronix-1502 - Manual (Page 17)

TM 9-4935-601-14-3&P
The 1502 operates from the battery supply for a minimum of 5 hours (including 20 chart recordings). If a
TEKTRONIX Y-T Chart Recorder is used, the 5 hours operating time will decrease by about 3 minutes for each
recording made beyond the 20 specified.
Charging the Battery
The battery pack can be charged at any temperature between 0°C and +40°C. It can be operated at any
temperature between -20°C and +55°C. For maximum charge capacity, the cells should be charged at +20°C
to +25° C.
The battery pack is fully charged in 16 hours when connected to an ac power source and the unit is
switched off. The 1502 may be operated while the battery pack is charging, however, the charging time will
increase. The batteries will not overcharge if the charger is left on longer than 16 hours. The 1502 can remain
connected to an ac source without damaging the batteries. Approximately once a month or every 15 charge-
discharge cycles, the batteries should be charged for approximately 24 hours. Approximately 30 minutes of
operating time can be expected from a 1 hour partial charge. To avoid reverse charging, the full 16 hour
charge should be completed in preference to a partial charge cycle whenever possible.
A battery can be damaged by reverse charging. This can occur if an individual cell becomes completely
discharged and the current from the other cells flow in a reverse direction through the discharged cell. Such a
case can develop due to cell aging, partial charging, or if a cell is replaced. The battery charger uses SCR
protection circuits to prevent accidental reverse charging. The SCR protection circuits automatically shut off
the instrument whenever battery voltage falls below about 10 V.
CAUTION
When the Anti-Deep-Discharge circuit is operating, the voltage circuits are turned off, but
there is still a small amount of current drawn from the batteries. This will further
discharge the batteries (at a slower rate) if the POWER switch is not turned off.
A 12 V dc power supply may be substituted for the 1502 battery pack by removing the pack from the unit
and connecting the power supply to the terminals inside the battery pack compartment.
CAUTION
When substituting a dc power supply or external battery for the battery pack, be sure the
polarity is correct. See Fig. 2-2.
Figure 2-2. Battery Connector Polarity
The power pack can be stored at any temperature between -40
°
C and +50
°
C with the battery cells either
fully or partially charged. The self-discharge rate of the cells increases with increased temperature. A fully
charged battery will lose about 50% of its charge in 3 to 4 months if stored at +20
°
C to +25
°
C. Therefore, the
battery pack should be completely recharged before using if it has been stored without power supplied to its
charging circuit for more than a month.
FRONT PANEL CONTROLS AND CONNECTORS
A brief description of the purpose of each front panel connector, pushbutton, control, and screwdriver
adjustment follows. A description of the controls of the plug-in modules is also included. Refer to Fig. 2-3 for
their location.
1. CABLE BNC Connector-delivers pulse to the test cable and receives the reflected return pulse.
2. FOCUS Adjusts the focus of the crt electron beam.
3. INTENSITY Controls the brightness of crt display.
4. POSITION/FINE Vertical position control of the crt display. The outer control is a course adjustment and the inner
control is a fine adjustment.
5. mp/DIV Selects the vertical deflection factor-5 mp/div to 500 mp/div (5-2-1 sequence).
6. POWER Push-off, pull-on switch -does not affect the battery charging circuit.
REV B FEB 1980
2-2