I Troubleshooting; G No Power - Sanyo PLV-70 Service Manual

I Troubleshooting

No Power
The possible causes of No Power are listed below. Please
check following and refer to power supply and protection cir-
cuits diagram in the figure opposite.
1. Stop the operation of power supply circuit due
to detection of abnormality.
- Detected the abnormality on the secondary power supply
lines.
Power failure detection diodes detect an abnormal volt-
age on the power supply. Check the shortage of second-
ary circuits, ICs, condensers, etc.
Check power supply lines, 9VA and 15.7V on the Drive
Board, and 3.3V, 5VD, 5VA, S5V, 9V and 15.5V on the
Main Board.
Check detection diodes, D1653, D1604 on the Drive
Board, and D235, D236, D2352, D2353, D234, D2351,
D1101, D1113, D451. D9551, D4291,D3101, D3102,
D4054, D3501, D3601and D4814 on the Main Board.
- Detected the operation stop of cooling fans.
Power failure detection diodes detect the fan operation
stop. Check Fans FN901, FN902, FN903, FN904, FN905
and FN906.
Check fan's power supply lines and detection diodes and
transistors D6610, D6612, D6613, D6614, D6615,
D6616, D6617, D6618 and Q6609 on the Power Sub
Board.
- Detected the abnormal temperature rise inside the projec-
tor.
Temperature sensor ICs detect abnormal temperature.
Check peripheral circuits and sensor ICs IC1691 on the
Sensor1 Board, IC1871 and IC1872 on the Main Board.
Thermal switch (SW905) detects abnormal tempera-
ture. Check peripheral circuits and SW905.
SW905...................... short in normal
SW905 opens when peripheral temperature is over 90°C.
- Detected the abnormality on the lamp ballast unit.
The lamp ballast unit outputs error signal (LAMP_DET) to
pin 123 of IC801.
LAMP_DET .............. High in abnormal
- Detected the over load/over voltage on power supply circuit.
Feedback circuits detect over load or over voltages.
Check PC602 and peripheral circuits on Power Board.
- Operated the mechanical protect on the Interlock switch
(SW902). Check lamp cover fixed correctly.
- Fuse (F601) open.
2. Abnormality occurs on drive signals for power
or lamp circuit.
- Abnormality on power starter signals (FAN_DRIVE/
FAN_SW).
FAN_SW signal is output from pin 137 of IC801 and
applied to power switching circuit through Q4807. It drives
the power oscillation circuit in the Power Board and
power supply for the cooling fans in the Sub Power
Board.
FAN_DRIVE/FAN_SW.... High in power on
Check FAN_DRIVE and FAN_SW signals, switching cir-
cuit Q6623, Q6624, Q6604, IC6604, IC6606, IC6603,
IC6606 and peripheral circuit on the Sub Power Board.
- Abnormality on fan drive signal (IC_RESET).
IC_RESET signal is output from pin 2 of IC801 and sent
to Q6616, Q6612 and Q6613 on the Sub Power Board.
They switch power supply lines, 9V, 10VA, 15.7V, 15VP,
3.4V.
IC_RESET ................ High in power on
Check IC_RESET signal, IC801 on the Main Board, drive
transistors and ICs Q6616, Q6617, Q6612, Q6611,
Q6613, Q6626, Q6602, Q6628, IC6608, IC6618, IC6607,
IC6601, IC6616 and peripheral circuits.
- Abnormality on power drive signal (LAMP_SW).
LAMP_SW signal is output from pin 138 of IC801 and
sent to pin 3 of K8L on the Main Board to drive the Lamp
Ballast Unit.
LAMP_SW ................ High in power on
Check LAMP_SW signal, IC801 and peripheral circuits.
3. Abnormality occurs on the power circuit.
- Abnormality on power primary circuit
Check Line filters, L601, L602, D604, Q601, DS601,
L611, IC651, D632, etc.
- Abnormality on power secondary circuit
Check D681, D682, D683, IC681, etc.
-42-