Tektronix WFM 601A, Service Manual

Page: 152 / 368

Maintenance
6–32
WFM 601A, WFM 601E, & WFM 601M Service Manual
2. Focus Amplifier Check
a. Using the digital multimeter, measure the voltage between TP1 and the
collector of Q2.
b. Rotate the front-panel FOCUS control and verify that the voltage varies
from 0 V
DC
to –300 V
DC
.
3. Z-Axis Amplifier Check
a. Use the digital multimeter to measure the voltage between TP1 and the
collector of Q6.
b. Short together the base and emitter of Q3. The collector of Q6 should be
near 0 V.
c. Short together the base and emitter of Q4. The collector of Q6 should be
near 100 V.
4. Grid Drive Check
a. Turn the Power to Standby. Use the diode check on the digital multimeter
to test CR2, CR4, CR5, CR6, CR8, and CR9 for shorts.
b. Turn the Power On.
c. Using the digital multimeter, measure the voltage between TP1 and the
cathode of CR8. It should vary between approxi40 and +170 V
as R53 (CRT Bias) is adjusted.
5. High Voltage Oscillator Check
a. Connect the oscilloscope probe to T1 pin 3 (Q6 collector) and the probe
ground to TP1. The signal should be a +70 V p-p, 22 kHz sine wave.
b. Check the voltages listed in Table 6–8 using the digital multimeter:
Table 6–8: High-voltage oscillator test
points
Circuit location Voltage
T1, pin 4 Approxi40 V
T1, pin 13 Less than +2 V
U2, pin 2 Approxi4.8 V
U2, pin 6 +4 to +11 V
CR9, cathode Approxi100 V