Tektronix 561A, Инструкция по эксплуатации

Страница: 14 / 55

Maintenance — Type 561 A
(TABLE 4-1 cont’d)
SYMPTOMS PROBABLE CAUSES CHECKS TO MAKE
— 12.2-Volt Power Supply (continued)
4. Excessive ripple on output.
C720A, C'20B, or C757.
6. Check D720 and D721, and C720A and
C720B.
7. Check voltage across Q734; should be
near 13.5 volts.
8. Check voltage across Q744; should be
0.8 volt or less.
Check capacitors.
Other Power Supplies
Symptoms and troubleshooting techniques for the -125- and + 300-Volt Power Supplies are similar to those de­
scribed for the — 100- and — 12.2-Volt Power Supplies
CRT Circuit
1. No high voltage at crt cathode.
Oscillator not operating.
V800 defective.
T801 defe ’ five.
V822 defective.
C822 shored.
R849 or RT52 open.
1. Check heaters of V822 and V832. If
heaters are glowing, the oscillator is
operating.
2. Check voltage at plate of V822, test
point [ 22 1 ; should be approximately
— 3.3 kv.
3. Check R849 and R852.
4. Check V822 and C822. If necessary,
check secondary winding of T801.
5. Check plate voltage of V800 (pin 9);
should be approximately +400 volts.
6. Check C807, R806, R807, and R804.
Also check primary winding of T801 .
2. No high voltage at crt control grid. T801 defe ctive.
V832 defective.
C830, C8J2, or C836 shorted.
R832, R835, R837, or R834 open.
Check voltage at plate of V832, test
point [23]; should be approximately
-3.4 kv.
3. High voltage outputs do not regulate
with change in line voltage, or cannot
be set to proper level.
V814 inoperative.
R816, R840, R841, R842, R844,
R846, R81 >, or R803 open.
C841, C8'l2, or C803 shorted.
1. Check to see if trace or spot on crt
can be focused.
2. Check V814, R815, R803 and C841.
3. Check R816, R840, R841, R842, R844,
R846 (test points [27], [281, [29], [30],
[31]).
4. Check C803 and C842.
4. Spot or trace does not focus properly. Incorrect outputs from High
Voltage Supplies.
R844 defective.
R864 defective.
1. Check outputs of both High Voltage
Supplies. Test points [22] and [23].
2. Check R844 and R864.
5. Insufficient display brightness. Defective crt.
Low outputs from High Voltage
Supplies.
R834 or R835 changed value.
Crt blanked.
1. Check outputs from High Voltage Sup ­
plies. Test points [22] and | 23].
2. Check R834 and R835.
3. Check crt pins 6 and 7 for approxi­
mately + 125v.
6. Trace will not align with horizontal
graticule markings.
Defective Beam Rotator Coil
L860.
R860 or R361 defective.
1. Check R860 and R861. Check physical
location of Beam Rotator Coil. Change
any defective components. It should be
possible to align the trace with the
graticule markings.
2. Check L860.
4-5