Troubleshooting; No Power - Sanyo MS6A Service Manual

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.
- 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 D69A, D69B, D69C and Q69A
- Detected the abnormal temperature rise inside the projec-
tor.
Temperature sensor ICs detect abnormal temperature.
Check peripheral circuits and sensor ICs IC4881 and
IC2881.
Thermal switch (TSW611) detects abnormal temperature.
Check peripheral circuits and TSW611.
TSW611.................... open in normal
TSW611 shorts when the peripheral temperature is over
90°C.
Thermal switch (SW902) detects abnormal temperature.
Check peripheral circuits and SW902.
SW902...................... short in normal
SW902 opens when peripheral temperature is over
100°C.
- Detected the abnormality on the lamp ballast unit.
The lamp ballast unit outputs error signal (LAMP_ERR)
to pin 47 of IC801.
LAMP_ERR .............. High in abnormal
- Detected the over load/over voltage on power supply circuit.
Feedback circuits detect over load or over voltages.
Check PC641, PC642 and peripheral circuits.
- Operated the mechanical protect on the Interlock switch
(SW904). Check lamp cover fixed correctly.
- Fuse (F601) open.
2. Abnormality occurs on drive signals for power
or lamp circuit.
- Abnormality on power starter signals (POWER, 5V_SW).
POWER signal is output from pin 1 of IC801 and sent to
pin 17 of IC1881, and output from pin 3 by the name of
5V_SW signal. 5V_SW signal drives 15.5V and 9VMCI
power supply circuits on the power board.
POWER/5V_SW ............ High in powered on
Check POWER and 5V_SW signals, 9V regulator circuit
Q65A, Q65B, Q65C, IC65A and peripheral circuit, 15.5V
switch circuit Q661, Q662 and peripheral circuit on the
Power Board.
- Abnormality on lamp ballast drive signal (BALAST_AC).
BALAST_AC signal is output from pin 39 of IC801 and
sent to pin 11 of IC1881, and output from pin 9 by the
name of BALAST_AC1 signal. BALAST_SW1 signal
drives the lamp ballast unit.
Check BALAST_AC and BALAST_AC1 signals and lamp
ballast unit.
- Abnormality on fan drive signal (FAN DRIVE).
FAN DRIVE signal is output from pin 41 of IC801 and
sent to pin 15 of IC1881, and output from pin 5 by the
name of FAN DRIVE1 signal. FAN DRIVE1 signal drives
fan supply voltages (12V/12V1) on the power board.
FAN DRIVE/
FAN DRIVE1 .............. High in power on
Check FAN DRIVE/FAN DRIVE1 signals, 12V regulator
circuits IC681, Q681, Q682, Q66A, IC671, Q671, Q672
and peripheral circuits.
- Abnormality on power drive signal (LAMP_BST_SW).
LAMP_BST_SW signal is output from pin 82 of IC801
and sent to pin 2 of IC1871, and output from pin 18 by
the name of LAMP_BST_SW1 signal. LAMP_BST_SW1
signal drives the power factor control IC on the P.F. board
through the Power board.
LAMP_BST_SW/
LAMP_BST_SW1 ............ High in power on
Check LAMP_BST_SW and LAMP_BST_SW1 signal,
photo-coupler PC643, transistors Q651, Q641 and
peripheral circuits.
3. Abnormality occurs on the power circuit.
- Abnormality on power primary circuit
Check Line filters, L601, L602, D614, L611, IC631, D632,
etc.
- Abnormality on power secondary circuit
Check D651, D652, D653, IC651, etc.
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