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CTV991206
Month of Issue: December 1999
Classification: White
TELEVISION TECHNICAL BULLETIN Page 1 of 1
MODELS
DV5105H DV5107H DV5132H
SYMPTOM Intermittent failure of the power supply.
CAUSE Various components.
ACTION If Q702 immediately goes short circuit when the set is turned on, check that D716 has
not gone short circuit or that T700 (chopper transformer) is not short circuit across
pins 7 and 2. Note that D716 is connected across Q702 emitter earth return resistor,
as this is only 0.22Ω, D716 needs to be removed before testing.
If the power supply works, but fails after being run on soak test, replace D708 and
D709, also check that the main smoothing block (C705) has not got loose rivets.
In some cases it is possible for the HT to rise significantly during standby, the normal
value of the HT in standby is anywhere between 120VDC and 130VDC ( this rise is
due to the line output load being removed). If this increases above 130VDC, there is a
problem. Check the feedback circuit around the opto coupler and D751.
Note that it is important that Q702 is replaced with the correct type or long term
reliability problems will ensue (MJF18006).
The HT voltage should be set to 113VDC on a blue screen (pull out the aerial and wait
a few minutes - the screen will turn blue due to lack of line sync).
REF NO DESCRIPTION PART NUMBER PRICE CODE
C705 Capacitor, 100uF 400V RC-EZ0104BMZZ AP
D708 Diode, 1N4934 RH-DX0519BMZZ AB
D709 Diode, 1N4934 RH-DX0519BMZZ AB
D716 Diode, 1N4148 RH-DX0045BMZZ AA
D751 Diode RH-DX0226CEZZ AC
Q702 Transistor, MJF18006 RH-TX0119BMZZ AL
T700 Chopper transformer RTRNZ0514BMZZ AU
Sharp Electronics (UK) Limited
Reference AVW031299-1
Revision 1
White – Carry out as required, Yellow – Carry out as required and whenever the unit comes in for service, Red – Carry out on all units
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