Tektronix 070-8462-03, Instruction Manual

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Preventive Maintenance
7–2
1735 HD High Definition Waveform Monitor
A 2% RMA flux content solder is recommended for making repairs in this
instrument. Cleaning of rosin residue is not recommended. Most cleaning
solvents tend to reactivate the rosin and spread it under components where it may
cause corrosion under humid conditions. The rosin residue, if left alone, does not
exhibit these corrosive properties.
If the circuit board assemblies must be removed for cleaning, follow the
instructions for removal/ replacement under the heading of Corrective Mainte-
nance.
After cleaning, allow the interior to dry thoroughly before applying power to the
instrument.
Visual Inspection
After cleaning, check the instrument carefully for improperly seated transistors
or integrated circuits, defective connections, and damaged parts. To prevent
additional damage in the case of heat-damaged parts, determine the cause of
overheating before replacing the damaged part.
Periodic checks of the transistors and integrated circuits are not recommended.
The best measure of performance is the actual operation of the component in the
circuit.
Static-sensitive Components
This instrument contains electrical components that are susceptible to damage
from static discharge. Static voltages from 1 kV to 30 kV are common in
unprotected environments. Table 7–1 shows the relative static discharge
susceptibility of various semiconductor classes.
Table 7–1: Static susceptibility
Relative susceptibility levels Voltage*
1 MOS and CMOS 100 to 500 V
2 ECL 200 to 500 V
3 SCHOTTKY SIGNAL DIODES 250 V
4 SCHOTTKY TTL 500 V
5 HF BIPOLAR TRANSISTORS 400 to 600 V
6 JFETS 600 to 800 V
7 LINEAR CIRCUITS 400 to 1000 V est.
8 LOW POWER SCHOTTKY TTL 900 V