PHILIPS 209U is an a.c/d.c mains powered radio, which is housed in an attractive
bakelite cabinet. It was made in 1946, and employs long, medium, & short
employs continental style valves, UCH21 (times 2), UBL21, and UY21. Do remove
the wire link connecting the two detector diodes in the UBL21 tube base, as
failure to remove it does cause hum.
the radio is of compact design, the components are tightly packed,
especially under-chassis. There is a service hatch, which is located under the
set, for ease of access for general repairs. Usually, the set requires
a rebuild, if it has not been used for years. The tuning capacitor cord drive
is usually found to be broken, and the two electrolytic capacitors need replacing.
It is a tricky manoeuvre to remove the chassis from the cabinet, once the back
is removed. All four side mounted control knobs are screwed down to their shafts
with a 3mm screw thread (access from under chassis holes). There are four other
screws, two for bottom of the chassis, and two for the cursor gantry. Even the
pilot lamp holder is difficult to access - held in the cabinet by a captive
screw. There is another screw holding the internal aerial system lead to the
gang drive cord is tricky to rewind, as the winding shaft is located more under
chassis. It is necessary to remove the cursor drive and the gang drum from the
tuning capacitor, in order to start the rewinding of the gang drive. It is also
essential to make up the exact cord length, with loops, before you start. I,
personally seal up the knots at each end of the cord with superglue, so that
you don't lose the loops as the spring begins to tighten. Philips used to use
cord grips for their drive cords, for that purpose, but you can not obtain them
any more. If you read the circuit diagram for the 209U set, you will notice
that the gang drive pattern is viewed as "if looking through the drive
drum" (well, it is located behind it !). To make it easier, I drew a "mirror
image" plan of the drive cord layout from the manual, and then worked from
that. You have to place the chassis on its back to start the 3.5 turns
of cord around the spindle. Once installed , then you can place the chassis
"flat" again, and place the front of the drive drum on the workbench,
so that it is parallel with the cord loops. Attach both loops to the spring,
and manoeuvre the cord around the inner rim of the drum. You can secure the
cord down to the drum with insulation tape (temporary measure) to secure it
whilst you pull the spring taught, with a pair of forceps. The drive drum can
then be installed back on the tuning capacitor shaft (and screwed back). The
temporary tape can then be removed from the drum, and then you can see if the
gang drive system is tight enough. The cursor drive is the easiest bit, and
this is slipped on the front of the drum.
main problems with this set, are :-
The failure of the scale lamp (25v @ 0.1 amps - no lamp shunt resistor). I managed
to use a 19v @ 0.097amp. It worked o.k
The failure of the rectifier anode load resistor (150 ohms). The vireous enamel
resistor chain is quite delicate in these sets, and has been known to fracture.
I bridge the o/c section with a suitable cement coated w.w resistor.
The electrolytic capacitors. These are paste types in my set (32 + 32uF @ 330V
D.C), and are secured by 22mm lock nuts. Both negative connections are isolated
from chassis !.Since the chassis is too small to put standard replacement
capacitors in, I remove the lock nut type originals, and open them up to remove
the old "innards", and dust from inside the old cans. I usually put
a hacksaw cut through the can, about 2.5 cm from the bottom. I also drill out
the rivet in the old positive connection, which removes the lower "innards"
and dust. When the can is cleaned out, I drill a small hole in the insulation
(for the new negative lead). Do ensure adequate ventilation during these processes,
and take necessary care (well, it goes without saying!!).
install a new radial 47 uF @ 450V D,C electrolytic on a two way solder tag -
the tag with the large hole, is for the bolt which makes up the new positive
lead. This is terminated by a large solder tag on the outside of the can
(where the old (+ )terminal used to be, and is affixed with nut & washer.
Once the new cap is soldered to the internal tags, a lead is taken through the
hole drilled through the insulation from the negative terminal, and soldered
in place inside. The two parts of the can are then ready for joining together
with superglue. The uneven join, can be covered with sticky-backed aluminium
all the pitch coated capacitors, the pitch does crack and fall off, and they
are often found to be "leaky".
NOTICE :- beware of accidentally touching all "floating" negative
electrolytic capacitor cans when testing these Philips type of radio, out of
chassis (those capacitors that are insulated from chassis). You can receive
a shock, if you place your hand around them, unintentionally, as the negative
line is at a different potential from chassis, so use precautions.
cabinet pin-stripes that are so familiar in various Philips radios, can be"
touched-up", using "Tipp-ex" (beige). If you are very careful,
you can make an excellent job. Remove all excess (carefully) with a damp cloth,
before it dries,