Hallicrafters T-506 scored

[Charlie]

Might be worth experimenting with some of the nasty knobs in those boxes you mention... find some with the film and see how they react to different treatments.

[bandersen]

Originally Posted by Phil Nelson

I have three Hallis:

http://antiqueradio.org/halli505.htm
http://antiqueradio.org/hallit-67.htm
http://antiqueradio.org/HallicraftersT-54Television.htm

The 505 and T-54 have the same chassis as the 506, only different cabinets. The T-67 is a typical late 1940s 10-inch set, apart from the pushbutton tuner.

Phil

Cool. Seems like you have (or are in the process of creating) a webpage for every set I've picked up lately

Anyone have a schematic for it ? I can only find the early version with 6SH7 tubes. This is the later chassis with 6AU6s.

Thanks!

[bandersen]

Originally Posted by Charlie

Might be worth experimenting with some of the nasty knobs in those boxes you mention... find some with the film and see how they react to different treatments.

Sure, great idea. I'll hold my nose and do some digging

[Phil Nelson]

I have the Riders and Sams for the 505/T-54. Both show the 6SH7 version.

If I'm remembering correctly, and these knobs are made of the same stuff, the material is breaking down internally, not being attacked by some evil mildew from the outside. That doesn't necessarily mean that sealing would be useless. Perhaps if you cleaned the knob and dried it really well, sealing it from moisture and oxygen would keep things stable for a long time.

People try all kinds of tricks to keep Predicta screen covers from breaking down. I polished mine with Novus #2 about 10 years ago, and it still looks the same. Not being a chemist, I have no idea whether these knobs are made of the same material.

My 505 project turned out fairly well, so I'm eager to redo the T-54, but there's a color set ahead of it in the queue.

Phil

[Sandy G]

I'm pretty sure nobody nearly 65 years ago ever imagined these rather slapdash, crude, feeble things would be coveted, prized possessions someday...Lots of people thought "Tell-A-Vision' was a passing fad then. And Hallicrafters really had more than they could say grace over, trying to meet demand for their radios...Altho they tried harder than most independents did to make TV a go...And they had a wealth of engineering background to draw upon, as well. And who could possibly have forseen in '46 that the mighty US consumer electronics industry had about 20, 25 years left to live, courtesy of a shattered, defeated nation, and an unremarkable invention made of sand & a couple wires ?

[peverett]

The US electronics industry is not in near as much trouble as many posters on this board seem to think. True, electronics manufacturing is worldwide now, but there is plenty going on in the US.

Texas Instruments is building a new IC fabrication plant in Dallas, IBM and the AMD Spinoff, Global Foundries have and are building IC fabrication plants in New York. Intel has many IC fabrication plants in the US. In addition to these other IC companies have fabrication plants here.

In addition to the above, many of the ICs used in consumer electronics today are designed in the US. Some of these are manufactured overseas, but the design work was done here.

The next time you purchase a consumer electronics item(or other item-such as an automobile) manufactured overseas, remember that a US designed/manufactured IC is probably included.

[electronjohn]

My guess is that Funky Knob Smell is caused by breakdown of urea in the plastic. I'm not a chemist...just play one on TV.

[Sam Cogley]

I will say that I've never noticed a weird smell from any plastics I've encountered with that white waxy residue. The smelly knobs might have a different internal chemistry with which I am not familiar.

[bandersen]

I've noticed it mostly on late 40s knobs. It's not really a strong smell. I first noticed it when I opened a small box of knobs that had been sealed for many years.

I've been studying that 505 schematic and it does seem pretty close to my sets other than the 6SH7 tubes. Weird design. Especially the power supply and HV portions.

Here are links to a schematic I scanned from Most Often Needed Television Servicing Information 1948 edition.

http://www.bobandersen.com/images/ha...5%20sch-01.jpg
http://www.bobandersen.com/images/ha...5%20sch-02.jpg

Phil - any concern about the series wired 7JP4 filament?

[Phil Nelson]

Originally Posted by bandersen

concern about the series wired 7JP4 filament?

Some folks install a little filament transformer to supply the CRT and wire a power resistor to take its place in the filament string. I did that for one of my series sets (don't recall which, offhand). I bought a transformer for my Pilot TV-37 but haven't put it in yet. It is a Triad F-13X.

Phil

[bandersen]

Originally Posted by Phil Nelson

Some folks install a little filament transformer to supply the CRT and wire a power resistor to take its place in the filament string. I did that for one of my series sets (don't recall which, offhand). I bought a transformer for my Pilot TV-37 but haven't put it in yet. It is a Triad F-13X.

Phil

Thanks Phil.

Sounds like a good idea - there's plenty of room to add one in.

Can you explain that crazy power supply? A 25Z6, 6X5 and a selenium rectifier!

Did you replace it with silicon? If you did, any change to the18 ohm resister in series with it?

Thanks again
Bob

[Reece]

In connection with that filament transformer for the CRT it would be a good idea to give the heater a soft start with something like a CL-90 inrush current limiter. This in series with the transformer primary has 120 ohms resistance at startup, and resistance drops gradually to about 7 ohms as the thermistor heats up, so the heater comes on gradually over part of a minute, helping preserve the life of a rare picture jug.

[Phil Nelson]

Yes, three rectifiers and seven electrolytics if I'm counting right. My National TV-7W has something similar, with a 25Z6 identified as a rectifier/voltage doubler and 6X5GT as a voltage tripler. Maybe something like that is going on here, although I haven't looked closely at either schematic.

A 6X5 rectifier is notorious in radio circles for developing a heater to cathode short. Various remedies are used, from installing a fuse to replacing it entirely. An Internet search may uncover some of those discussions. Perhaps the risk is negligible in a series string set, which has no power transformer to fry.

I'm a fan of the CL-90 ever since I put one in an RCA color set. Cheap and effective, just understand that it may get hot.

When I did my 505, I probably would have replaced the selenium rectifier with a 1N4007 diode and not changed anything else. Some people add more resistance in series with the new diode.

Phil

[bandersen]

Thanks for the info guys. I think I have a few 6X5s in my stash - hopefully one is good.

I'll add some CL-90s to my shopping list

[batterymaker]

My one TV in my collection is a T-54.

After the recapping, the first image I got on it was....Austin Powers....