Wednesday, 27 February 2019

SONY WEGA TRINITRON KV-HA & KV-HW SERIES TVs HORIZONTAL OUTPUT TRANSISTOR BLOWS OUT

SONY WEGA TRINITRON KV-HA & KV-HW SERIES TVs HORIZONTAL OUTPUT TRANSISTOR BLOWS OUT

Horizontal output transistor [2SD2624-CA] blows off as soon as the set is switched ON; without allowing time to find the fault by any measuring instruments.

There are two resons for this fault.
The first one is with its deflection yoke.  If any turns in the winding of the deflection yoke get shorted each other, the horzontal output transistor will get shorted [collector to emitter].  But this fault is very rare to Sony Televisons.
The second one is with fault capacitors at the horizontal output circuit.
Beofre switch ON the set, after replacing the horizontal output transistor, replace these capcitors.  [C-812-0.033MFD; C-811-1MFD 250V; C-807-330PF 2KV; C-808 0.0082MFD; C-814 12KPF; C-813 330PF.
In most cases, dry soldering points at the terminals of C-812 or value detereiation of this capacitor will be the cause. If you switch ON the set without C-812, it is sure and certain that the horizontal output transisoor will get shorted.  Replace this capacitor with same capacitance value.  If the value changes, it will effect both high-tesion voltage and width of the picture. Select a good quality one.

This fault is common to all CRT based televisions, irrespective of brand