Diode Checks - Tektronix TR 502 Instruction Manual

Polarity &
~
~
1st Figure
Voltage
2nd Figure
Multiplier
DIPPED TANTALUM CAPACITOR MARKING
A AND B CASE
CAPACITANCE AND VOLTAGE COLOR CODE
CODE FOR CAPACITANCE
Rated
Voltage Color
VDC 25 °C
1st Figure ~ 2nd Figure ~ Multiplier
IN PICOFARADS
Maintenance Instructions-TR 502
3-4 Black 0 0 None
3~ Brown 1 1 X10
3-10 Red 2 2
X
102
3-15 Oran e 3 3
X103
3-20 Yellow 4 4
X104
3-25 Green 5 5 X10 5
335 Blue 6 6
X106
Fig. 6-3. Diode polarity markings .
3-50 Violet 7 7
X10
Gray 8 8
NOTE
3 White 9 9
(1733) 1735-9
C1664-7 4
If a substitute is not available, check the transistor
Fig. 6-2. Color code for some tantalum capacitors .
with a dynamic tester such as the Tektronix Type 576
Curve Tracer or fhe 5CT1 N Curve Tracer for the
5000-Series Mainframe . Static-type testers, such as
a ohmmeter, can be used to check the resistance
2. Use only good components for substitution .
ratio across some semiconductor junctions if no
other method is available . Use the high resistance
ranges (R x 1000 or higher) so the external test
3. Turn
the power
off before a component is sub-
current is limited to less than 6 mA . If uncertain,
stituted .
measure the external test current with an ammeter.
Resistance ratio across the base-to-emitter or base-
to-collector junction usually runs 100 :1 or higher.
4 . Be sure the
component
(transistor or IC) is inserted The ratio is measured by connecting the meter leads
properly in the socket (see
Fig .
6-4 or the manufacturers across the terminals, noting the reading, then rever-
data
sheet) .
sing the leads and note the second reading .
5 . After the operational
check,
return the good com-
Diode Checks .
Most diodes can
be checked
in the
ponentstotheiroriginalsocketstoreducecalibrationtime circuit by taking measurements across the diode and
and run-in period .
comparing these with voltages listed on the diagram .