Power Supply Voltage And Ripple Limits - Tektronix 2246 1Y Service Manual

Maintenance—2246 1Y and 2246 Mod A Service
NOTE
Use 20 MHz bandwidth limiting on the test
oscilloscope. A higher bandwidth may pro­
duce higher observed ripple levels.
If the power-supply voltages and ripple are within
the listed ranges in Table 6-4, the supply can be
assumed to be working correctly. If they are outside
the range, the supply may be either misadjusted,
operating incorrectly, or excessively loaded. The
power supply adjustment procedure is given in the
Power Supply, Display, and Z-Axis subsection of
Section 5 (the Adjustment Procedure).
A defective component elsewhere in the instrument
can create the appearance of a power-supply prob­
lem and may also affect the operation of other
circuits. Use the power
(schematic Diagrams 14 and 15 in the foldouts) to
aid in localizing a loading problem to a particular
circuit.
9. Check Circuit Board Interconnections
After the trouble has been isolated to a particular
circuit, again check for loose or broken con­
nections, improperly seated semiconductors, and
heat-damaged components.
Test Point
(+ lead)
Nominal
Test Point
Supply
(+ lead)
Voltage
+130 J1204-11
+58
J1204-10
+15 J 1204-7
+7.5 J1204-8
+5.0 J1204-1,2
-5 .0
J 1204-5
-7 .5 J1204-9
-15 unreg
J1204-6
aA t ra te d load.
6-8
distribution diagrams
Table 6-4

Power Supply Voltage and Ripple Limits

Limits (-10°C
to 55°C)
Min
+ 127
+55
+ 14.6
+7.4
+5.0
-5 .2
-7 .5
-15.5
10. Check Voltages and Waveforms
Often the defective component can be located by
checking circuit voltages or waveforms. Typical
voltages are listed on the schematic diagrams.
Waveforms indicated on the schematic diagrams by
hexagonal-outlined numbers are shown adjacent to
the diagrams. Waveform test points are shown in
the circuit board illustrations.
NOTE
Voltages and waveforms indicated on the
schematic diagrams are not absolute and
may vary slightly between instruments. To
establish operating
those used to obtain these readings, see the
Voltage and Waveform Setup Conditions pre­
ceding the waveform illustrations
Diagrams section.
Note the recommended test equipment, front-panel
control settings, voltage and waveform conditions,
and cable-connection instructions. Any special con­
trol settings required to obtain a given waveform are
noted under the waveform illustration. Volts/Div and
Sec/Div settings of the test oscilloscope for a
waveform are indicated in the waveform illustration.
Max 60-150 Hz
+135 70 mV
+59 40 mV
+ 15.6
8 mV
+7.6
8 mV
+5.3 30 mV
-5 .4 4 mV
-7 .8 4 mV
-16.6 10 mV
conditions similar to
in the
P-P Ripple a
20-40 kHz
70 mV
120 mV
4 mV
4 mV
20 mV
4 mV
4 mV
100 mV