TW-2000
Restoration Project Doug Moore, KB9TMY |
Editor's Note: Rig pictured is not actual rig restored |
This little gem was given to me by an ex-Hallicrafters employee, who extracted it from his basement where it had been for the last 25 years. Bringing it up on a variac produced no smoke, but alas, no sound either. There was some noise when switching bands, so it seemed like the power supply and audio system was working. The main dial cord was sticking and slipping, and the band indicator gizmo didn't work at all. On the plus side, there was no loud hum, so perhaps the electrolytics were still good. Opening the back, I was greeted with the potent odor of cadmium oxide. Removing the chassis was fairly simple, two hex nuts holding the panel and three screws in the bottom holding the chassis. The internal antenna plugged into the tuner section, so could be unplugged with ease. |
After chassis removal, I gave
the unit a preliminary cleaning with an old paintbrush to remove
most of the cadmium oxide. This was followed by a wipedown with a
damp rag and a very light coat of de-ox-it. I tried to be careful
not to ingest or inhale any of the cadmium dust. Next, I took a
look at the underside of the chassis and was greeted by a couple
of handfuls of the dreaded "black beauty" capacitors,
some of which showed signs of leaking oil. Rather than just do a
bulk recap of the entire unit, I thought I'd investigate why the
set didn't play, and possibly show up any drastic problems first.
The bandswitching method on this set is quite unique, resembling
the Standard Coil TV tuner of days gone by. (In fact, I'd swear
it had some of the same parts.) I quickly discovered that I could
get some signal on the AM band by touching the center lug of the
three gang variable. I concluded that the oscillator and mixer
were working, but the RF amplifier stage was dead. Since the
bandswitching turret blocked the converter and RF amplifier tube
sockets, I removed the 1U4 tube and plugged in a test adapter.
The problem was quickly discovered, zero volts on the 1U4 plate.
Naturally, the suspect components were buried under the turret
beneath the tube socket. In order to access this area, it was
necessary to temporarily remove about three of the snap-in band
coils. I found an open resistor, (R102) and while I was in the
area, replaced the "black beauties" which would be
hidden when I replaced the band coil modules. Snapping these back
in and firing up the set, I was rewarded by music from a local AM
station.
The next project was to restring the dial cords. There are three
cords, two for the main tuning, and one for the bandswitching
indicator. To get at the dial cords, you need to remove the glass
dial cover, the dial pointer, the metal dial plate, the tuning
and volume knobs, and the speaker baffle. The easiest thing to do
in the latter case is unsolder the speaker wires and leave the
speaker bolted to the baffle. For restringing the cords, I used
45 pound test dacron fishing line. (Gudebrod #518) I had a
stringing diagram for the TW-1000, which is almost identical
electrically, but somewhat different mechanically. The bandswitch
stringing was the same, but the main tuning stringing was
different. Since the old cord was still mostly intact, I just
made my own drawings of how it was done. After the old cord was
removed, I carefully cleaned and lightly lubed all the pulleys
and shafts, then re-cleaned the main tuning shaft in the area
where the cord wrapped around. (Any lube left here will do more
harm than good.) On the cord ends, I used tied loops, then dabbed
the knots with Duco cement. An alternate technique is to use
small brass eyelets to form the loops. The loop can be easily
adjusted to the correct length, and then the eyelet is squeezed
with a pair of pliers, and dabbed with cement. Following the
stringing, everything was tested with the knobs temporarily back
in place, and all worked well. The baffle, dial plate and dial
glass were carefully cleaned, using only WATER on the dial
markings, then reassembled. The dial pointer was attached prior
to the reattachment of the dial glass bezel, and after
positioning, was fastened to the cord with another dab of cement.
When resoldering the speaker leads, be VERY careful not to touch
your new dial cord with the soldering iron!
The next task was to finish cleaning the contacts on the
bandswitch, lube the cam on the bandswitch detent, and give the
volume control a spritz of cleaner. I replaced capacitor C16,
which bypasses the B- to the chassis, with a UL approved part. I
then examined the remaining "black beauty" capacitors,
with the thought of replacing any that looked suspicious, but
finally decided to replace them all. The set was then aligned,
and played on the bench for a couple of days. While I was "burning
in" the chassis, I cleaned the inside of the wood case, then
rubbed down the outside surface with auto upholstery treatment.
The guts were then reinstalled. The looks and sound were better
than I expected for a 47 year old radio.
Later that same day, my wife saw the radio in the basement and
asked what it was. I told her it was Hallicrafters' answer to the
Zenith Trans-Oceanic. She said, "You know, that radio is the
first one you've had that I'd let you put in the living room."
Well, to conclude an already long story, the TW-2000 ended up in
the living room and now I can't get it away from my wife. She
likes to listen to a station from Italy. Maybe it's time to start
her on Morse code, or just ask her if she wants to help me finish
the SX-28.
This page last updated 31 Mar 2001.