Tektronix 543B, Instruction Manual

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Maintenance —Type 543B/RM543B
Fig. 4-5. Standard ElA color code for metal-film resistors.
Color Code Sequence
TABLE 4-1
Color
s ’St
Sig.
Fig.
2nd
Sig.
Fig.
3rd
Sig.
Fig-
Multiplier
(±1
%
Tolerance
Black 0 0 0 1
Brown 1 1 1 10 1
Red 2 2 2 100 2
Orange
3 3
3 1,000
Yellow 4 4 4 10,000
Green
5
5 5 100,000
0.50
Blue 6 6 6 1,000,000
0.25
Violet 7 7 7 10,000,000
0.10
Gray
8
8 8
100,000,000 0.05
White 9 9 9
1,000,000,000
Gold 0.1
5
Silver
0.01
No Color
10
TROUBLESHOOTING
General Information
This portion of the Instruction Manual includes information
to facilitate more efficient troubleshooting of the Type 543B
if a trouble develops. During troubleshooting, information
contained in this section of the manual should be correlated
with information obtained from other portions of the manual.
In general, troubleshooting an instrument con be divided
into two parts: isolating the trouble to the originating circuit
and the actual location of the defective component. The
following general procedures are included to help isolate
the trouble to the circuit involved. The circuit trouble­
shooting information should be used to locate the defective
component.
Circuit Isolation
The Type 543B can be divided into 7 major circuits. These
circuits are:
1. Time-Base Trigger.
2. Time-Base Generator.
3. Horizontal Amplifier.
4. Vertical Amplifier.
5. Power Supply.
6. Crt Circuit.
7. Calibrator.
Although the Type 543B is a stable instrument, it is pos­
sible for circuits to get out of calibration, thereby producing
an apparent trouble. Before proceeding with any detailed
trouble analysis, be sure that the trouble cannot be corrected
by means of a normal calibration adjustment. If there is
any doubt, recalibrate the entire suspected circuit using
the procedure given in Section 5.
When a trouble occurs in the instrument, first rccheck the
settings of all controls to see that they are set properly.
Then turn the front-panel controls throughout their range
to see what effect, if any, they have on the trouble. The
normal or abnormal operation of each control mey help to
indicate the circuit in which the trouble is located.
When vertical-system troubles are encountered, isolate
the trouble to the Type 543B or the vertical plug-in unit.
The best way to do this is by substituting another vertical
plug-in unit. If the trouble appears to be in the plug-in unit,
refer to the Maintenance section of the plug-in unit In­
struction Manual.
If the instrument does not operate at all, check the
obvious things first. Check if the instrument is plugged in
and there is power at the socket. Check the line fuse. Check
that the pilot lamp and tube heaters are lit. When the
obvious indications of trouble have been checked, proceed
to a more detaiiled anaysis of the trouble.
Unusual troubles may often occur due to a failure in one
of rhe low-voltage power supplies. Also, the circuits of
the Type 543B make it possible for an incorrect voltage to
affect one circuit more than another. Consequently, a
power supply trouble should be considered as a possibility
in virtually any type of failure which may occur within the
instrument. If there is any doubt as to whether a power
supply may be causing the trouble, the regulated output and
ripple of that supply should be checked before proceeding
further with the troubleshooting procedure. If the output
voltage and ripple of a regulated power supply are correct,
that supply can be assumed to be operating properly.
Circuit Troubleshooting
After the trouble has been isolated to a particular circuit,
perform a complete visual check of that circuit. Many
troubles can be found most easily by visual means. If a
visual check fails to detect the cause of the trouble, check
the tubes or transistors used in that circuit by replacing
them with tubes or transistors known to be good. Most of
the troubles which occur in Tektronix instruments result
from tube or transistor failures. Be sure to return any tubes
4-5