Troubleshooting; No Power - Sanyo PLC-XT10 Service Manual

■ Troubleshooting

No Power

The possible causes of No Power are listed below. Please
check following and refer to the chapter "Power supply and
protection circuit" in the Chassis Block Diagrams on the pre-
vious page.
1. It does not operate the power supply circuit due
to detection of abnormality.
- The abnormality on the secondary power supply lines was
detected.
One of the power failure detection diodes detects an
abnormal voltage on the power supply. Check the short-
age of secondary circuits, ICs, condensers, etc.
Check power supply lines, FAN1, 16V, 14,5V and
15AUDIO on the Audio Board, and 5V, 5VD, 15.5V, 3.3V,
15VP, 9V, 5V1, 5V_DV, 2.5V1, 12V, 3.3_AV, 3.3V_AD1,
3.3V_AD2, 3.3V_AD3, 2.5V1 and 12V on the Main
Board.
Check detection diodes, D5511, D5562, D6502, D031 on
the Audio Board, and D3102, D3103, D4814, D1561,
D451, D1571, D2501, D6381, D3252, D3253, D241,
D242, D243, D3103, D3251 on the Main Board.
- The cooling fans was stopped.
One of the power failure detection diodes detects the fan
operation stop (FAN_LOCK) signal. Check Fans FN901,
FN902, FN903, FN904, FN905, FN906 and FN907.
Check the FAN_LOCK signal.
Fan Error : H
And this signal drives Q4891 on and the P-FAIL signal
becomes low.
- The abnormal temperature rise inside the projector was
detected.
Temperature sensor ICs detect abnormal temperature.
Check peripheral circuits and sensor ICs IC2821 on the
Sensor Board, IC1871 , IC1872 and IC1873 on the Main
Board.
Thermal switch (SW905) detects abnormal temperature.
Check peripheral circuits and SW905.
SW905...................... short in normal
SW905 opens when peripheral temperature is over 90°C.
Reset switch
The projector does not allow any controls rarely when the
abnormality of power or operation occurs inside the projec-
tor. In this case, press the reset switch on the rear panel to
restart the projector.
- The abnormality on the lamp ballast board was detected.
The lamp ballast board outputs error signal (LAMP_DET)
to pin 123 of IC801.
LAMP_DET .............. High in abnormal
- The Interlock switch (SW902) is not turned on.
Check lamp cover fixed correctly.
- Fuse was opened.
Check the fuse on the Line Filter Board.
2. Abnormality occurs on drive signals for power
or lamp circuit.
- Abnormality on power starter signals (FAN_DRIVE/
FAN_SW).
The FAN_SW signal is output from pin 137 of IC801 and
applied to power supply circuit through Q4807 as the
name of FAN_DRIVE. It drives the fans on and off.
FAN_DRIVE .................. High in power on
Check FAN_DRIVE signal, IC801 and peripheral circuits.
- Abnormality on the drive signal (IC_RESET).
The IC_RESET signal is output from pin 2 of IC801 and
sent to the power DC board to switch the power on and
off.
IC_RESET
Check IC_RESET signal, IC801 and peripheral circuits.
- Abnormality on the lamp drive signal (LAMP_SW).
The LAMP_SW signal is output from pin 138 of IC801
and sent to IC4891. IC4891 also receives the P-FAIL sig-
nal and outputs the drive signal to pin 4 of K8L and the
lamp ballast board.
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, thermal switch (SW905), interlock
switch (SW902) the Power AC board and Power DC
board.
About the LED indicator flashing
The projector will be automatically turned off when the inter-
nal temperature of the projector exceeds the normal oper-
ating temperature, or the cooling fans stops, or the power
supplies in the projector are failed.
- If the TEMP WARNING indicator (red) is flashing, it may
detect the abnormal temperature inside the projector.
Check the air filters and remove the object near the intake
and exhaust fan openings, and wait until the WARNING
TEMP indicator flashing stops, and then try to turn on the
projector.
- If both of the TEMP WARNING (red) and READY (green)
indicators are flashing at the same time, It may defect the
cooling fans and power supply circuits. Check fan opera-
tion and power supply lines.
-46-
High in power on