Read Sharp 76FW-54H Service Manual online
DA100 (50Hz) Chassis – Article for Television Magazine
Neon
illuminated
NICAM or OPC
LED's illuminated
Plug or internal fuse has failed
Check Bridge Rectifier,Q701, Q702,
Q703 and D712
No
Short Circuit
Check HT
(D720 Cathode)
Ok
Yes
Power Supply is working correctly
Check data communication
(see LED's Fault code table)
No
Short circuit on a supply other
than the main HT
Line Drive Missing
goto chart 2
140v
Between 20 - 40 Volts
Zero
Press CH+ button
on main PWB
Remove R623
No
Yes
CTV not faulty
Standby mode
Protection circuit operating
Ensure that the loudspeakers are connected
Check IC1001 pin 100
(5v = Normal\zero= standby)
Power Supply in standby mode
Check IC702
Power Supply
Starts
No Change
Power Supply Starts
For A Few Seconds Only
Chart 1 - No 140v rail
Before switching on ensure that the aerial is not connected
Check IC702
pin15 = 0v
Check
D735 and
C720
HT has increased
replace IC705
Note:
Always fit the latest four pin device.
(Technical bulletin CTV2002 05 02)
(Technical bulletin CTV2002 05 02)
Power Supply not working
Replace R713 and R714.
Check D712, Q702 and Q703
Yes
Note:
An avalanche diode (D735) has been added across C720
Later production D735 has its own location
Figure 62: Fault Finding Flow Chart 1
Page 65 of 80
Sharp Electronics (UK) Limited - March 2003
Revision 2
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