Read Sharp 66GS-62 (serv.man17) Technical Bulletin online
CTV 2004 03 02
Date of Issue: 10
th
November 2004
Classification:
White
TELEVISION TECHNICAL BULLETIN
Page 2 of 3
Sharp Electronics (UK) Limited
Reference AvW 10 03 2004 - 2
Revision 4
White – Carry out as required
Yellow – Carry out as required and whenever the unit comes in for service
Red – Carry out on all units
Dead set (low or no power supply output)
If the power supply does not kick off - start up oscillator running, but Q702 and Q703 not energising the chopper
transformer - the HT will be low (up to 40V) or zero. Q702 or Q703 breaking down internally can cause this, even
though they can measure all right on a meter.
If the power supply does not kick off - start up oscillator running, but Q702 and Q703 not energising the chopper
transformer - the HT will be low (up to 40V) or zero. Q702 or Q703 breaking down internally can cause this, even
though they can measure all right on a meter.
If the feedback from the voltage feedback circuit based around he opto-coupler, IC703 is incorrect then the HT will fail
to rise. Q713 has been known to fail short circuit, but other components in this area can cause the same fault.
to rise. Q713 has been known to fail short circuit, but other components in this area can cause the same fault.
Intermittent Operation
Unit intermittently will not start up from standby, shuts down or the line collapses. Q606 failing intermittent, it may read
perfectly alright on a component test. This transistor is part of the protection feedback circuit.
Unit intermittently will not start up from standby, shuts down or the line collapses. Q606 failing intermittent, it may read
perfectly alright on a component test. This transistor is part of the protection feedback circuit.
Set Enters Standby at Switch On
There is a protection line that monitors the outputs to the loudspeakers. If this output becomes unbalanced, then the
protection pin on the processor (pin 63 - PROT) will go low, putting the set into standby. This normally happens if the
loudspeakers are left unplugged when servicing the set. Depending upon the component tolerances on the chassis,
this fault can also happen intermittently while the set is running.
There is a protection line that monitors the outputs to the loudspeakers. If this output becomes unbalanced, then the
protection pin on the processor (pin 63 - PROT) will go low, putting the set into standby. This normally happens if the
loudspeakers are left unplugged when servicing the set. Depending upon the component tolerances on the chassis,
this fault can also happen intermittently while the set is running.
Takes a Long Time to start up or may not start up at All
There are two possible causes of this problem - D724 can go leaky or short circuits, reducing the +5V supply, or the
processor can fail. There are two different types of microprocessor fitted to this model depending upon the size of the
EEPROM (IC1003). See parts issues Technical Bulletin for more information on this.
There are two possible causes of this problem - D724 can go leaky or short circuits, reducing the +5V supply, or the
processor can fail. There are two different types of microprocessor fitted to this model depending upon the size of the
EEPROM (IC1003). See parts issues Technical Bulletin for more information on this.
Intermittent Turning On
When the set is left in standby, it may turn on. This fault can be very intermittent. This problem is caused by failure of
C1013.
When the set is left in standby, it may turn on. This fault can be very intermittent. This problem is caused by failure of
C1013.
Location of C1013 on the Print Side of the PWB
Intermittent line collapse or turning off
This problem can be caused by one of the HT feedback resistors (R742, R743, R744 and R745) on the secondary of
the power supply. Usually it is R743 that fails and it is best to check this component by substitution as the fault may not
respond to flexing the PWB.
This problem can be caused by one of the HT feedback resistors (R742, R743, R744 and R745) on the secondary of
the power supply. Usually it is R743 that fails and it is best to check this component by substitution as the fault may not
respond to flexing the PWB.
Click on the first or last page to see other 66GS-62 (serv.man17) service manuals if exist.