Tektronix 543B Instruction Manual page 24

Maintenance — Type 543B /R M 543B
Fig. 4 -4 . Loosening the crt base clamp.
13. Reconnect the anode ond neck-pin leads (observe color
code).
14. Turn on the oscilloscope and obtain a free-running
sweep on the crt.
15. Check the trace alignment with the graticule lines. If
the trace is not parallel with the graticule lines, adjust
the TRACE ROTATION control to realign the trace.
16. Remove all smudges and dirt from the crt face with a
soft, lint-free cloth dampened with denatured alcohol,
17. Replace light filter or crt protector plate, crt bezel and
bezel nuts.
TROUBLESHOOTING AIDS
Schematic Diagrams
Schematic diagrams for each circuit in this instrument are
located at the back of this manual. In addition, a block
diagram provides an overall picture of instrument operation.
The circuit reference designation for each electronic com­
ponent in the instrument is shown on the circuit diagrams
along with important voltages and waveforms. Component
description and tolerance is given in Section 6 of this
manual,
The following list shows the circuit reference designations
associated with each circuit in this instrument.
4-4
Circuit Numbers—
1 — 99.................Time-Base Trigger
100 — 199.................Time-Base Generator
300 — 399.................Horizontal Amplifier
460 — 599.................Vertical Amplifier
600 — 799.................Power Supply
800 — 869................ Crt Circuit
870 — 899................ Calibrator
Switch Wafers
Switch wafers shown on the schematic diagrams are
coded to indicate the position of the wafer in the complete
switch assembly. The number portion of the code refers
to the wafer number counting from the front or mounting
end of the switch toward the rear. The letters 'F' and 'R'
indicate whether the front or rear of the wafer is used
to perform the particular switching function.
Wiring Color-Code
All wiring in the Type 543B is color-coded to facilitate
circuit tracing. The widest color stripe identifies the first
color of the code. The background color indicates the
following: white—positive voltage, tan— negative voltage,
gray— unregulated voltage.
The regulated power-supply wiring is identified by the
following code.
+500 vo lts... .Green-black-brown on white background.
+350 vo lts... .Orange-green-brown on white background.
+ 225 volts. . . . Red-red-brown on white background.
+ 100 volts.. . . Brown-black-brown on white background.
—150 volts. . . . Brown-green-brown on tan background.
The heater wiring is indicated by a white background and
a blue first stripe. The remainder of the wiring in the Type
543B is not color-coded in any particular manner; the color
used is to facilitate point-to-point circuit tracing within the
instrument.
Resistor Color-Code
Some stable metal-film resistors are used in this instrument.
These resistors can be identfied by their gray body color.
If a metal-film resistor has a value indicated by three signifi­
cant figures and a multiplier, it will be color-coded accord­
ing to the EIA standard. If it has a value indicated by
four significant figures and a multiplier, the value will be
printed on the body of the resistor. For example, a 333 k
resistor will be color-coded, but a 333.5 k resistor will have
its value printed on the resistor body. The color coding
sequence is shown in Fig. 4-5 and Table 4-1.
Composition resistors used in this instrument are color-
coded according to the EIA color code.
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