Tektronix 1L30, Instruction Manual

Page: 45 / 129

Maintenance— Type 1130
tions and positions for the types of transistors used in the
Type 1L30.
Notch
i ^ ^ n n j ¥ i n r y i n r i
Ceramic Strip
Stud
Chassis
Spacer 'Stud Pin
L..
Fig. 4-12. Typical ceramic strip assembly.
oriented to reduce or control circuit capacitance and induc­
tance. After repair, the circuits of the instrument may need
recolibration.
Replacing Components on M etal Terminals
When soldering metal terminals (e.g., switch terminals,
potentiometers, etc.) ordinary 60/40 solder is satisfactory.
The soldering iron should have a 40- to 75-watt rating and a
Ve inch chisel tip.
1. Apply only enough heat to make the solder flow freely
and form a good electrical connection. Do not use excessive
solder. Excess may impair the operation of the circuit or
cover o cold solder joint.
2. Clip off excess wire that may extend past the soldered
connection and clean the- area with flux-remover solvent.
Removing and Replacing Switches
' Single wafers on the VOLTS/CM or DISPERSION-COUPLED
RESOLUTION switches are not normally replaced. If any
of these wafers are defective, the entire switch should be
replaced. Refer to the Electrical Parts List to find the unwired
or wired switch part numbers.
C A U T IO N
W h e n disconnecting or connecting leads to a w a fe r-
type switch, do not let solder flo w around and b e ­
yond the rivet on the switch term inal. Excessive
solder can destroy the spring tension of the con­
tact.
Transistor Substitution and Replacement
Transistors should not be replaced unless they are actu­
al!'/ defective. However, temporary substitution is often a
convenient way to detect defective transistors. Before substi­
tuting a transistor, it is recommended that circuit conditions
be checked to be certain that an exact replacement will not
be dam aged. Return transistors to their original sockets if
they are tound to be good. Some transistors can be inserted
incorrectly into their socket. Fig. 4-13 illustrates the connec-
TROUBLESHOOTING
Attempt to isolate trouble to one circuit through operational
and visual checks. Verify that the trouble is actually a mal­
function within the Type 1L30 and not improper control
setting or malfunctioning associated equipment. Note the
effect the controls have on the trouble symptoms. Normal
or abnormal operation of each control helps establish the
location and nature of the trouble.
Check the instrument calibration or the calibration of
the affected circuit. The trouble may be corrected after
calibration. Before changing any adjustment during this
check, note the position of the adjustment, so it can be
returned to its original position after the check. This will
facilitate recalibration after the trouble has been found and
corrected.
Check* circuit voltages and waveforms against those shown
in section 9 of this manual. Figs. 4-14 and 4-15 provide cir­
cuit board wiring drawings and component layout informa­
tion for the honeycomb and the phase lock assemblies. If
the trouble cannot be isolated to a circuit, start with the
power supply voltages, then proceed consecutively from one
circuit to the next until the problem is localized.
NOTE
Voltages an d w avefo rm s shown on the diagram s
are not absolute an d m ay vary b etw een instru­
ments.
Most voltage measurement can be taken with a 20,000
ohms/volt DC voltmeter. Do not use a low-volts range on
a high impedance circuit. Use a higher range or an oscillo­
scope with a
1 0 X probe. Accuracy of the voltmeter should
be within 3% for all ranges.
Connections to the honeycomb chassis and the Phase-
Lock chassis are made through square-pin connectors and
clips. These connectors make convenient test points for trou­
bleshooting, since much of the circuitry is inaccessible with
the circuit boards installed and in the assembly.
Once the trouble has been isolated, it may be desirable to
refer to the Circuit Description in section 3 for a description
of the normal circuit operation.
C A U T IO N
Use care when measuring voltages or w aveform s.
The small size and high density of components in
this instrument establishes a condition such that
an inadverten t movement of the test probe or use
of oversized probes m ay short-circuit betw een com­
ponents.
Check circuit conditions before disconnecting voltages to
make certain bias voltages are not removed which might
cause excessive overloads.
In-Circuit Diode Checks
In circuit diode checks may be performed with a voltmeter.
A comparison check of the voltages on each side of the di-
4 4
*. fly