Sharp XG-MB70X (serv.man13) Service Manual ▷ View online
33
XG-MB70X
TROUBLESHOOTING TABLE
Checking the basic operation
Does the power LED light up or flash in
red or green?
red or green?
Go to "Checking the power supply system".
Does the set function with its keys or the
remote controller?
remote controller?
Go to "Checking the peripheral circuits of
the microprocessor".
the microprocessor".
Does the cooling fan rotate, and the lamp
turn on?
turn on?
Go to "Checking the lamp light-up".
Is the user menu displayed?
Go to "Checking the peripheral circuits of
the formatter".
the formatter".
Does the analog RGB input function
normally?
normally?
Go to "Checking the RGB input".
Does the component input function
normally?
normally?
Go to "Checking the component".
Does the VIDEO input function normally?
Go to "VIDEO input check".
Does the LAN function?
Go to "Checking the LAN".
Does the RS-232C function?
Go to "Checking RS-232C".
Does the autofocus function?
Go to "Checking the autofocus".
End.
NO
YES
NO
YES
NO
YES
NO
YES
NO
YES
NO
YES
NO
YES
NO
YES
NO
YES
NO
YES
34
XG-MB70X
Checking the power supply system
Is 13V output to pins (9) and (11) of
P1707?
P1707?
Is 6V output to pins (1) and (3) of P1707?
Go to "Checking the power unit".
Go to "Checking the power unit".
Is the connector of P1708 fully inserted?
Is the voltage of 6V applied to both ends?
Is the voltage of 6V applied to both ends?
Replace the thermal fuse.
Is B+5VAT output from IC1776?
Check IC1776 and peripheral circuits.
Is BU+3.3V output from IC1708?
Check IC1708 and peripheral circuits.
Is BU+2.5V output from IC1733?
Check IC1733 and peripheral circuits.
Go to "Checking the peripheral circuits of
the microprocessor".
the microprocessor".
NO
YES
NO
YES
NO
YES
NO
YES
NO
YES
NO
YES
35
XG-MB70X
NO
YES
NO
YES
NO
YES
NO
YES
NO
YES
NO
ABNORMAL
YES
YES
Checking the power unit
Is each connector of the power unit
fully inserted?
fully inserted?
Securely insert the connectors.
Is the lamp door closed completely?
Fix the lamp door with screws.
Is the bimetal broken?
Replace the bimetal switch or restore
by pressing the red button.
by pressing the red button.
Is AC voltage applied to both AC input
ends of DB7001?
ends of DB7001?
Replace F7001. If other parts are
damaged, replace them.
damaged, replace them.
Is DC voltage of approx. 6.25V output
to both ends of C726?
to both ends of C726?
Check D707 and the peripheral circuits
of IC702 on the primary side. If
defective, replace them.
of IC702 on the primary side. If
defective, replace them.
Is DC voltage of approx. 370V output to
the cathode of D701?
the cathode of D701?
Check the primary-side circuits such as
IC701. If defective, replace them.
IC701. If defective, replace them.
Replace the ballast power supply.
Is the specified voltage output to each
output terminal of EA701?
output terminal of EA701?
Check the secondary-side circuits of
T701. If defective, replace them.
T701. If defective, replace them.
Check the PWB circuits on each output
side.
side.
36
XG-MB70X
Checking the peripheral circuits of the
microprocessor
microprocessor
Are the voltages of approx. 3.3V and 2.5V
applied to both ends of C2030 and C2029
respectively?
applied to both ends of C2030 and C2029
respectively?
Go to "Checking the power supply
system".
system".
Are the oscillations of 133MHz and
64MHz output from pin (3) of X2001 and
pin (3) of X2002 respectively?
64MHz output from pin (3) of X2001 and
pin (3) of X2002 respectively?
Check the peripheral circuits of X2001
and X2002.
and X2002.
Does each terminal of R2039, R2040,
R2042, R2048 and R2050 change?
R2042, R2048 and R2050 change?
Check IC2201 and IC2202. IC2003 is
defective.
defective.
Do pins (95) and (96) of IC2201 change?
Check IC2203. IC2201 is defective. The
I2C bus does not function normally.
I2C bus does not function normally.
Do pins (74) to (77) and (89) to (94) of
IC2201 change when any key is
operated?
IC2201 change when any key is
operated?
IC2201 is defective. The keys do not
function normally.
function normally.
When the power button is pressed, does
the voltage of pin (7) of IC2005 become
3.3V?
the voltage of pin (7) of IC2005 become
3.3V?
IC2003 is defective.
Do pulse-shaped waveforms appear at
pins (1), (2), (5) and (6) of IC2005?
pins (1), (2), (5) and (6) of IC2005?
IC2005 is defective.
Does the voltage of pins (2) and (6) of
IC2006 and pins (3) and (6) of IC2007
change?
IC2006 and pins (3) and (6) of IC2007
change?
IC2006 or IC2007 is defective.
Is the voltage of pin (9) of IC3560 5V?
IC3560 is defective.
Does the fan rotate?
Check the power supply circuit or fan
circuit on the main circuit.
circuit on the main circuit.
Go to "Checking the lamp light-up".
NO
YES
NO
YES
NO
YES
NO
YES
NO
YES
NO
YES
NO
YES
NO
YES
NO
YES
NO
YES
