Philco 48-1001 - 1948 vintage
 

Found this on Phila. CL a few weeks ago for $100. Finally got it last night. An aspiring architect found it in a house she was rehabing. She saved it, held it for a few years and now it had to go for space.

"It had snow the last time I tried it". The words you do not want to hear. The copper visible through the power cord should be a clue.

A soft start on the Variac proved her right (with the same cord) and it came up with sweep but vertically challenged and dim. The dim faded to nothing after 10 minutes. Every control was noisy or ineffective.

Another try today was better. Still no cleaning or chassis removal. The vertical adjustments worked today and got the snow full screen. The Beltron got the CRT from .3ma with no life to .85ma with a good life test. The dust-o-meter says this is all original.

With no inspection of the underside, this is amazing that it tries to work after 50 years. Perhaps some previous work I have yet to find, but what a soldier. At work I have about 30 dead plasmas after only 4 years. Another thread for another day.

It's antenna inputs are the early Philco 4-pin connector. The wider 2 pins are the LF (ch 2-6) and the narrower 2 pins are the HF (ch 7-13). I did not try to force a signal in tonight.

My house is in the middle of major remodeling, so the pix are of the the set in the worst of conditions on my living room floor with a small lamp nearby with no signal available tonight. If they post in order, the pix are pre and post Beltron. The rest of the story will be a while.

It also has the Philco 8-position tuner of the day. The tech would tune the set for the local channels on the nearest position on the tuner. No fine tuning for the customer. Mine is set for Philadelphia in the day. Ch's 3, 6, 10, 12. And 12 did not appear for long after this set was mfgd but the tab is there. A later addition?

And if anyone has a spare Philco 4-pin connector available, let me know.

Dave A

GREAT score !

Yeah,, very nice.
Dan

you dont see those everyday , great score !

IIRC, as a driving-age teenager I saw channel 12 when it was commercial. That had to be between 1955 and the middle of 1957, although my mind may be transposing this with Newark's channel 13 as it also began as a commercial station before becoming the PBS' WNDT in 1962. In the summer of 1950 when we got our first TV, Philadelphia had only 3,6, and 10, so based on my memory anyway, it must have been added.

That 4-pin antenna connector is similar to the one used in a CT-100, although it uses only two wide pins. If it's compatible with your Philco, I can send you one.

Pete

Channel 12, in that era, was originally WDEL-TV with most programming originating from Wilmington. It transferred to new ownership as WVUE - The Broader View. It later went dark and returned to the air as an educational station with the transmitter relocated to the Phila tower farm in Roxborough.

Philco engineers believed fine tuning was unnecessary because its early TVs had an AFC circuit using voltage derived from the audio detector. The tuner oscillator should be set using a DC voltmeter in the AFC test jack. Set for 0 volts or just a touch negative since they tend to drift positive.

The fine tuner will not affect the sound detector voltage polarity on later TVs using intercarrier sound, so Philco reverted to traditional fine tuning.

That's a great example of an early TV.

Don

Don,

Looking at my Rider's on this set it also adds "Place a jumper to ground at junction of R68 and C57 to remove AFC from oscillator." This is in the 48-1000 section. The 48-1001 has nothing other than the schematic. Is this jumper needed in my 1001 version?

And if you can explain the "beam bender" concept that may keep me from adjusting something I should not touch. It looks like it takes the focus voltage straight to ground. Just adjusting the focus control rolls the whole screen to starboard (clockwise).

And WDEL was a Crosley station licensed to Wilmington. Now PBS WHYY-TV and still licensed to Wilmington.

Pete, thanks but I found the connector needed. Where I saved it from I have no idea.

And thanks to the rest who just enjoy a good find and some good information from AKer's.

Dave A

Dave,

Pretty sure I can help with the 4 pin connector. When it comes to it. you can simply strap the L & H band inputs in parallel, only one of the 2 input lines is terminated at any given channel.

It is not uncommon for an old 40s vintage set to come back to life when brought up slowly on a viriac, but it will not last. A full recap is the only long term solution. I am sure Chuck A would love to do it. :-).

No fine tuning required, as the AFC control loop in the set keeps the tuning perfect! Don't know why other manufacturers did not adopt the concept.

I was never very fond of the Philco 8 position tuner, but the reasoning was sound. Back in the 1940-early 50s, there would never be more than 8 stations in any given major metropolitan area, as decreed by the FCC. So 8 was enough.

That is a great set. Same chassis as the somewhat more stylish 48-1000, but still a under-appreciated set, in my opinion.

John,

Looking further down the schematic, the LF/HF inputs do end up in the same place at a switch. My guess is that they were separate for tuned rooftop antennas of the day. I just want Ch 3 or 4 for a VCR tuner feed. Tuned for 3 right now.

Of course the set needs the full treatment. I am from the variac-now-fix-it-later school. Especially if my seller did the damage for me first. But I am willing to give it all the time it needs to go quietly on it's own terms.

And having a 48-1000 also, they will look great side-by-side.

I think Chuck A is driving here now to look at this as we speak.

Dave A.

Dave, check that schematic again. The VHF HI and LO antenna inputs got to separate pairs of input pins on the tuner drum inserts. The HI and LO inserts have a coil between either the HI or LO inouts, but not both. So if you have a source which provides both HI and LO VHF signals (such as a cable system), you can dreive the HI and LO inputs in parallel. If you have separate HI and LO VHF antennas, you drive the HI and LO inputs separately.

You can almost bet that every TV on ebay that still has a powr cord has been pluggen in and tried, no matter what they claim.

I have taken a few courses from the variac-it-now fix-it-later school myself. Mostly harmless, as long as one knows when to quit.

Good luck with it. I think I still have a spare chassis & tuner if you need anything.

John / Dave,

I think I'd rather trade you a restored 1001 than get into another one of those.:D

Only 73 caps to change.

The antenna connections are separate on each of the tuner "plugins", pins 3 & 7 are LF and 4 & 6 are HF. To eliminate interference Philco recommended shorting pins 4,5,6 together on the HF plugins, and 3,5,7 on the LF plugins.

Also for areas with low signals there was a "Channel Adjuster" kit available. Consisted of a dual pot and switch assembly, it added a voltage divider to the contrast control that allowed you to manually adjust the voltage on the AFC bus from negative to zero to positive.

Beam Bender was Philco speak for ion trap.


Chuck

Dave:

In practice, most techs aligned the oscillator slugs while the TV was in the cabinet so they didn't ground the AFC. I just used a VOM or VTVM and adjusted for -0 volts. The jumper will give more meter deflection, but the setting becomes very touchy. If you are a purist, then grounding the 1001 at the same point will give the same effect as on the 1000, but neither one is essential.

As Chuck says, Philco used beam bender as it is the correct name for the ion trap. It doesn't trap ions, it bends the beam so ions don't hit the screen. Somehow "ion trap" evolved early in the industry and stuck.

Since the focus coil and controls are loaded directly on the B+ supply, replacing the 5U4s may reduce the focus control effect on centering. If not, set for best focus and re-center using the focus coil mechanical adjustments.

Most antenna connections were just jumpered from hi to low at the antenna plug. That works fine in strong signal areas. Fringe area reception required more careful matching. The Philco service books go on at length about proper matching. Unless you are using the TV in a weak signal area or are attempting to eliminate interference, I doubt you will see any difference.

Don

Someone was selling some of these kits NOS on eBay for a while, I tried to get one but was always outbid, couldn't understand the demand for something that only a handful of people would need?

Eric,

I doubt it was something many people wanted in 1948 either, I have a few NOS units around here someplace also.


Chuck

Just finished a 48-700 and have a 48-1000 waiting
 

Finally finished the 48-700 electrical restore. A bit of fun with the HV caps. Tall one shorted about 3 hours after the 3 day long variac power up cycle completed. Typical!! Metal HV oil cap under chassis arced internally often enough to be a pain so it was retired. Big one stayed inplace disconnected, the oil one gone. 0.1uf Tesla caps are available to 10kv and fit nicely under the chassis. 6kv one for the video coupler also available and cheaper. All a bit pricey, but readily available on Ebay. Definately do not want to get across those 10kv'ers!! The rest was standard cap, resistor and wire replacement. Video and Audio alignment went perfectly. Used a Leader 480 U80 S&M. Does a nice job in the 24Mhz IF. John F helped me with a few tuner strips. Had to rewind 2 to get on freq. I needed ch 2 4 and 6 for my home TV 3 channel station. Not worried about any 2009 digitial BS. I'm still very low power analog throught out the house. 4 servers, 1 RAID, 3 agile modulators, KMPlayer and bingo! 24/7 RF to rabbit ears. Just like the 40-50's! Love XPMedia Center and Xvid...all the old programing all the time.

Anyone have a source for the tuner number/stars repros?? Might be able to scan them in.
Jack