Hallicrafters T-54
 

This is the Hallicrafters T-54s mentioned in the grneral TV thread.

How do you remove the HV box? Its looks to be a really stupid design,
requiring wire unsoldering. Is there another way?

If nobody answers, send a PM to UberVacTuber, that's Dan Jones (of Predicta fame). He just restored one not long ago.....

Yes, you must unsolder several (4 or 5) wires under the chassis to remove the assemly.

jr

edit add: actually 6 wires, counting the HV output.

I hate that crap. I bet the cat that designed it later worked for GE.
No reason not to make things physically seviceable, Maybe a few
bucks at most on $200+++
Its a pet peeve.......

73 Zeno:smoke:
LFOD !

Last night I got a raster. Easy recap job. I got the HV box recapped by undoing only 4
wires, the B+, B- (it has a -100v or so B- supply), ground, and HV. The filaments
can remain connected. I did this by unscrewing the bakelite (?) plate and the
box itself. Then you can lift the box and unscrew the aluminum plate on the bottom.
Then the plate comes off, and you wiggle the bakelite loose and remove the box.
Its then easy to service. Getting two screws back in the aluminum plate is finicky.
The HV wire was toast so I replaced it.

I got 4.7kV HV. Next job is getting reliable contact from the pushbuttons. The
buttons often fly off. What do you do about the looseness problem ... I don't want
to use strong glue.

Maybe put a paper towel between the shaft and the button then insert. Something to make it a slightly tighter fit like that could keep the buttons on without glue.

I got it working properly. It needed just the recap and a full careful alignment, as
it was badly out. Of course it didn't work well at first ... hum in the picture.
Arggggh ... it was a ground loop in my modulator setup. Looks good now,
nice sharp picture, though still retrace lines in dark low contrast
pictures.

Only one problem: the brightness control could not turn down far enough.
A zener diode in the grid lead pulled down to the -120 supply
with 1 megohm did the trick. One could of course pull the cathode
up more, but that would get it fairly close to the heater-cathode
rating of the CRT.

Is the HV stable or does it drop considerably after the set has been on for a few hours?

jr

For glue, perhaps a dab of rubber cement? May have to re-do it every now and then, but at least it'll come off when required.

It seems quite stable, but I have the lid off the box. Its also
exactly as speced in Rider's, 4.7 kV.

Oh yes, I forgot ... the original purpose of the whole thread!

The plate cap of the HV rectifier is awfully close to the lid of its box.
Is that safe? Should I install insulation? Should I go to a perforated
metal lid for cooling?

Or, I could install standoffs so the lid had 1/4 inch of
clearance both for HV purposes and ventilation.

Many people leave the lid off. There seems to be a fairly frequent problem of the HV fading away after the set warms up to some point. Some even install a small fan to cool the HV section. The exact cause isn't known but seems like it is a quirk of the HV coil. This must not have happened when the sets were new.

The pushbuttons popping off is not a problem ... with the front on, they are
captive. And the loose one are still held on OK.

Now I need knobs. I need 5 of them. These are presumably push-on to 1/4 inch
spline shafts. They are also use in similar-era Hallicrafters radios such as SX43,
S38B, S53, SX62, etc., or at least they look the same.

Alternatively, as I am very non-picky, I need 5 push on black plastic knobs about 1 inch in diameter. I don't know the correct diameter.

I find nothing obvious on the internet.

Possibilities? (I think they're repros, though.)

http://www.renovatedradios.com/product.php?product=235
http://www.renovatedradios.com/product.php?product=236

They look right, but these shafts are the push-on fluted ones. If I recall
correctly, those don't use setscrews.

And 5 of them would be $50!

Doug McDonald