Detailed Procedure - Tektronix 4010 Maintenance Manual

~
Do not put the Terminal in Graph Mode with the
LOCAL/LINE switch at LINE and the TSTROBE"
to
CSTROBE jumper connected. Doing so may dam-
age the display screen.
At the lower right corner of the pedestal, remove the
shield which covers the transformer terminals. (It is held in
place by two screws on top.) Determine what voltage the
transformer is wired for by comparing the connections
against the diagram on the inside surface of the pedestal
cover. If a variable AC power supply is available, it will be
set to that value. If the indicated supply is not available,
record the transformer wiring condition so that it can be
restored upon completion of the adjustment procedure.
Then rewire the transformer connections to agree with the
available voltage supply. See diagram inside the front cover
for instructions.
Install an approriate slow blow fuse (2 A for 115 V or
1.25 A for 230 V) and replace the shield to minimize shock
danger. If the fuse mounted in the front cover is to be used
during the adjustment, it can be pushed (not pulled) from
its holder, or the holder assembly can be removed from the
front cover, as desired.
WARNING
I
Dangerous voltages exist in the fuse and transformer
circuits. Keep the line cord disconnected while
working in those areas.
Check the remaining fast blow fuses for proper sizes.
Their values should be: F21-2 A, F41-6 A, F61-2 A.
Adjustment-4010 Maintenance
Detailed Procedure
1. Low Voltage Power Supply Check/Adjustment
(R27-Reg Voltage)
NOTE
Early power supply boards had filaments connected
from J78-pin 1 (-20 V) to Jl1-pin 1 (+20 V).
Some later boards had the filaments connected from
J78-pin 1 (-20 V) through a selectable resistor to
Jl1-pin 1 (+20 V). The selectable resistor was used
to drop the filament supply to the proper level. The
procedure that follows pertains to boards marked PA.
a. After the preliminary procedure has been completed,
connect the line cord to a variable power source
(autotransformer) which is set to the voltage for which the
transformer is wired.
b. Turn the Terminal power switch ON, and place the
LOCAL/LIN E switch at LOCAL.
c. Using a voltmeter which has .05% or better accuracy
at 15 V, adjust R27 to obtain +15.000 V at the +15 V test
point indicated in Fig. 4-5. (Connect the voltmeter
reference lead to the ground point shown in Fig. 4-5.)
d. Measure the various power supply voltages as listed in
Table 4-1. Test points are shown in Fig. 4-5. Record all
voltages in Table 4-2. (Make duplicate copies of Table 4-2
for future use.)
TABLE 4-1
Power Supply Voltage Limits
Supply Limits Voltage
Ripple (P-P)
Comments
+15 V +14.025 to +15.075 10 mV Adjust R27 for +15.000 V; readjust if necessary to
+5V +4.9 to +5.1 10 mV
compromise so that +15, +5, and -15 V supplies are
-15V
-14.850 to -'15.150 10 mV all within limits with line voltage at mid-position as
well as at high and low limit
-20 V Unreg
-17.6 to -22.4
2.8 V
+20 V Unreg
+17.6 to +22.4
2.8 V
+20 V Fil 35.5 to 41 V more
positive than -20 V 2.8V
Not adjustable
supply value
+175 V Unreg +155 to +195 6V
+328 V Unreg +289 to +367 8V
@i
4-9