THORN 1590 CHASSIS

The problem is that the 2.5A fuse between the rectifiers and
the regulator blows when the set is switched on – the
250mA mains fuse remains intact. I take it there is a short-
circuit somewhere but everything seems to be in order.
Towards the right side there is a large metal heatsink
with the AU113 line output transistor mounted on it. The
transistor is secured by two nuts and screws. Only one
screw and nut is in actual contact with the print. Remove
these, thus isolating the transistor’s collector, then check
whether the fuse still blows. If it doesn’t, check the
transistor for a collector -emitter short. If the transistor is all
right check the two rectifiers W13 and W14 which are fed
from the line output transformer. If one of these is found to
be short-circuit check its reservoir capacitor, C110 (10uF)
and C111 (1µF) respectively