No
picture or sound. Standby stays lit;
steady.
The
standby light stays On; when the set is powered up. No other functions. No video or audio. No symptom of EHT generation.
The
standby light is On, means the SMPS section circuit is working. If not; there will be no standby light, as
5VDC to it will be absent; which too is generated by SMPS.
So
it is clear that there is some other problem/s to other DC voltages generated
by the SMPS transformer.
Checked
all the DC voltages at the Cold Side of the SMPS.
Measured
the +B voltage. Ok. Shows around 111.75VDC. It is normal in this condition, as there is
no load to it, because the EHT section circuit is not working. When it start to work, this voltage will go
down to 110VDC; and should be.
It
is clear that the horizontal output transistor is not leaky, and there is no
other short circuited component/s at the horizontal output section
circuit. If were, this +B voltage too
might drop down.
Checked
the other voltages. The 30VDC output
from the SMPS found to be absent.
Checked the continuity of the SMPS transformer winding to this voltage.
OK.
Checked
the rectifier diode connected to generate this voltage [D913 – BYV28]. Measured shorted junction. About (0.002Ohms)
Desolderd
it out from the circuit, and measured the junction resistor to it again. Shorted junction, confirmed.
Soldered
an other new diode in place [on the foil side; just for a test], and switched
ON the set.
The defective Diode
Ok. The blue screen came on.
Checked
the +B voltage now. Measured
110.03VDC. absolutely normal.
Connected
to external Ariel. The on-air program
received. Picture and sound is OK. But, the ‘Menu’ selection was not possible.
On
checking, one of the micro switches soldered on board was jammed.
Replaced
it. Checked the set for an hour. No
further problem detected. Ready to
deliver.
