PHILCO A547B.
. This very
attractive A.C mains valve radio was made in 1947, and employs long, medium,
and two short wave bands. The cabinet is brown moulded resin.
It is a common fault in these sets to have
problems with the smoothing and reservoir electrolytic block ( 30 + 30 uF@
350 volts working). The option is to have the original block reformed, or to
fit a replacement block. I chose the latter (to save time), and fitted an
L.C.R replacement 50 + 50 uF @ 450 volts. This brought some life back in to
the receiver. It is wise to also check the value of the resistor that feeds
the anode of the 6Q7 valve (220k ohms), as they always seem to drift off
their tolerence value. I also replaced leaky coupling capacitors in the
audio circuits.
I am quite pleased with the quality of the
sound output on this set. The next stage is to do some repairs on the inside
of the cabinet, as previous repairers have damaged the upper r.h (looking
from rear of the set) chassis fixing hole (self-tapping). I will fill the
existing damaged hole with epoxy resin, and then will try and re-bore the
hole with the self-tapping screw (covered with grease), whilst the glue is
in the "plastic" stage of setting.
I also will try and replace the 50k treble
control (c/w single pole mains switch), with one of a similar value, but
having a double pole mains switch. This will make it safer in operation, as
at present, only the neutral line of the mains is switched. I have such a
control, albeit with a slightly shorter shaft.
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