Sony TVP-08, Training Manual

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29
PS Troubleshooting
Overview
The key to troubleshooting shutdown problems is to determine if the prob-
lem is on the power supply board (G) or one of the other boards in the set.
In this section we will give you steps to follow to make this distinction.
Troubleshooting
Often shutdown problems occur too quickly for an indication to be given
by the self-diagnostics (flashing Timer LED). These are usually caused
by the power supply, but not always. The procedure below will guide you
towards the resolution of this type of a problem by notifying you if the
problem is with the power supply’s G board.
Symptom: Shutdown - No indication given by self-diagnostics. Timer LED
continuously flashes.
1. Unplug CN6106 from the G board. If the set comes up with sound but
no picture, replace or repair the D board. If the picture does not come
back up, reconnect the plug to CN6106 and move to the next step.
2. Unplug CN6102 from the G board. If the set comes up with no sound,
replace or repair the K board. If the sound does not come back up,
reconnect the plug to CN6102 and move to the next step.
3. Unplug CN6105 from the G board. If the set comes up, replace the D
board or replace IC5005 and IC5006. If it does not, move to the next
step.
4. Check fuses PS6101 and PS6103 on the G board. These fuses are
for the +7 volt line. If they are open, the set will shut down immedi-
ately. If they are OK, move to the next step.
5. We have unplugged all the connectors at this point that can be dis-
connected and have the set partially run. We can run the set fully
unloaded if we lower the AC voltage. First fully unload the G board
from the rest of the set by unplugging CN6102, CN6104, CN6105 and
CN6106. Now supply 55VAC to the set and press the power button
on the remote or the front panel. The power relay will click and the
Timer LED will flash continuously. Now you can check the voltages of
the power supply using the table below. It is very important that you
use 55VAC. If you raise the voltage to 60V, the supply will shut down
because of OVP. If the voltage is below 50VAC, there will not be
enough voltage to turn on the power relay and it will chatter.
The following table shows the voltages present with the supply fully un-
loaded and 55 volts AC applied.
Measurement Point Normal Voltage Voltage Unloaded with
55VAC applied
CN6106-1
+135 +78
CN6016-3 -135 -133
CN6106-5 +15 +9.9
CN6106-6
-15 +12
CN6105-1 +22 +10.7
CN6105-6 -22 -10.9
CN6104-4
+7 +5.6
CN6104-7 +11 +10.3
CN6104-9
+33 +31
Other problems
·
More often than not, no sound is caused by a problem with PS6103
and PS6104. Please note this is a very unlikely problem. Shutdown
caused by the K board is often indicated by the self-diagnostic circuit,
causing the Timer LED to flash eight times. If this type of shutdown
occurs, unplug CN6102. If the set operates but there is no sound,
replace or repair the K board.
·
If the set displays a symptom of no sub deflection, fuses PS6105 and
PS6106 on the G board should be checked.