Visual Inspection; Static-Sensitive Components; Table 6-1: Static Susceptibility - Tektronix 1725 Instruction Manual

Maintenance

Visual Inspection

Static-Sensitive
Components
6–2
(high-velocity air can damage some parts). Hardened dirt or grease may be
removed with a cotton-tipped applicator dampened with a solution of mild
detergent and water. Abrasive cleaners should not be used. If the circuit board
assemblies must be removed for cleaning, follow the instructions for removal/re-
placement under the heading of Corrective Maintenance.
After cleaning, allow the interior to thoroughly dry before applying power to the
instrument.
CAUTION. Cleaning fluids:
Do not allow water to get inside any enclosed assembly or component. Do not
clean any plastic materials with organic cleaning solvents, such as benzene,
toluene, xylene, acetone, or similar compounds, because they may damage the
plastic.
After cleaning, carefully check the instrument for defective connections,
damaged parts, and improperly seated transistors or integrated circuits. The
remedy for most visible defects is obvious; however, if heat-damaged parts are
discovered, determine the cause of overheating before replacing the damaged
part, to prevent additional damage.
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.
This instrument contains electrical components that are susceptible to damage
from static discharge. Static voltages 1 kV to 30 kV are common in unprotected
environments. Table 6–1 shows the relative static discharge susceptibility of
various semiconductor classes.
Table 6–1: Static Susceptibility
Relative Susceptibility Levels
1
2
3
SCHOTTKY SIGNAL
4
SCHOTTKY TTL
5
HF BIPOLAR TRAN-
6
Voltage
CMOS 100V – 500V
ECL 200V – 500V
250 V
DIODES
500 V
400 to 600 V
SISTORS
600 to 800 V
JFETS
1725 PAL/NTSC Vectorscope