Tektronix 549 Instruction Manual page 54

Maintenance— Type 549
Symptoms
c. Check operation and voltages
for erase generator circuit.
11. Image can not be a. See CRT operating precautions
completely erased. given in the Operation Section.
Care of Storage Screens.
Negative adjustments.
bration procedure.
12. Screen has poor a. Perform checks
contrast.
b. Check
MODE LEVEL control.
c. Recheck Calibration procedure
to set operating level.
13. B a c k g r o u n d a. Perform check
brightens after stor­
b. Turn EN HA NC E MODE control
age.
to OFF.
c. Check
adjustment.
14. IN TEG R A TE in­
a. Check voltage at junction of
operative. R1196 and SW 1196.
approximately
mally,
IN TEG R A TE button is depressed.
a. Perform checks
15. Enhance mode in­
operative.
b. Check
pulse
amplitude and
AB of etched circuit board with
Q 11 3 5 and Q1145 removed from
socket.
4-8
Checks
See Cali-
6 6
b and d.
setting of ENHANC E
6 b.
Collimation electrode
Should be
+ 1 5 0 volts nor-
and increase when the
6 b and 6 d.
for negative trigger
approximately 8 volts in
1
/cs wide at pin
(Sweep should be free-
Symptoms
running at 1 ASEC/CM).
c. Check operation of Q1135 and
Q1145
Reset Enhance width adjustment
(see Calibration procedure) if the
transistors are replaced.
a. Perform step 10 and check
16. Erase Program in-
operative.
b. Check voltages and waveforms
with
diagrams.
c. W ith sweep free-running at 1
μ SEC/CM, check for an unblank­
ing
board assembly.
d. W ith sweep free-running check
for
proximately
at the junction of R902 and D902.
e. Check Auto Erase multivibrator
operation by observing waveform
with
of circuit board assembly.
17
W i l l not cyde
a. Check for reset pulse with test
with the A U TO ERASE
oscilloscope at pin X of circuit
switch in A F T E R
board assembly when the ERASE
A N D RESET button is depressed.
SW EEP position.
b. Check operation of Q935 and
Q945 by direct replacement.
c. Perform check
d. Check voltages against those
shown on the Auto Erase circuit
diagram.
Checks
by direct replacement.
6 c.
those shown on schematic
pulse at pin AD of circuit
negative trigger pulses ap­
8 volts in amplitude
test oscilloscope at pin E
6 c.