Capehart Farnsworth 661P Aquisition

[pendulum]

This Capehart 661P had been listed on Craigslist for a few days, and today I made the 3 hour drive to pick it up. Upon seeing some photos of the set, I had assumed at some point the mask had been widened and the cabinet refinished, as the set looked dramatically different than any other example I had seen of this set.



When I got the set home, the first obvious fact was the rusty backside of the set. However, the remainder of the set and underneath are rust free and in good shape.





The picture tube is a farnsworth branded one, which has a neat label and interestingly no aquadag coating, even though there is a grounding strap for it.



Looking in the cabinet, I can see that the set was approved June 15, 1949, which seems pretty late for this model.



I'm starting to think that perhaps at the end of this models production, Capehart decided to use up the old cabinet design with parts from some of the newer models. This model Capehart for 1950 has a really similar crt mask.



Also though the control labels are mostly gone, the one that is left, which is behind the safety glass, clearly shows that it was on a wood finish, not the yellow that other versions of this same model has.




I will start working on this set in the next few weeks. If anyone with this set could take some photos of the knobs I am missing I would really appreciate it. Additionally, anyone with ideas on this set I would love to hear them.

[David Roper]

The mask is no doubt original to that set. The grill cloth on the other hand....

[pendulum]

Originally Posted by David Roper

The mask is no doubt original to that set. The grill cloth on the other hand....

Forgot to mention that. Grill cloth is for sure a replacement, there are still remnants of the original style. It is the same red with gold diamonds as other versions of this set have.

[Phil Nelson]

Great score -- congratulations! This set has an interesting electronic design, with air variable capacitors in the tuner and an outboard horizontal/AFC chassis, and it performs well after restoration.

This article has some restoration notes on the 661-P:

http://antiqueradio.org/CapehartFarn...Television.htm

If you send me an email via http://antiqueradio.org/contact.htm, I'll send you some close-up photos of the knobs on mine.

Regards,

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

[Radiotronman]

Great early set, awesome find!

[ronl]

Very interesting pendulum,
a different version of this farnsworth chassis. i have gotten help from the arf forum with my 651p and learned a lot about this chassis over the years. never seen this version! chassis is very simular but that mask is different. hardware around the crt neck is different too.i have a unique tuner but might because it was for the canadian market? i discovered the arf forum after finding some data there after years of searching(owned this set since 1981). eventually found this site too.
here is the discusions on arf.
http://www.antiqueradios.com/forums/...p?f=3&t=122536

http://www.antiqueradios.com/forums/...p?f=3&t=143501

im sure the arf forum (thanks for the service info Tim!!)can help you with the knobs.(thanks radio pup)!! help is here too.here is a youtube of my set when it was last ran.(when analog ntsc was on the air)
enjoy that set! there is not a lot out there.seen more ctc 100's online-lol

https://www.youtube.com/watch?v=9EKBFUSVHF4


fyi-this set was very simular to the set that was used in the
addams family-the politician eposide.

RonL

[pendulum]

It's been a while, but I finally finished recapping the set and gave it a first power up. Results were pretty good considering I haven't replaced any of the resistors and I still need to replace one oddball capacitor I didn't have on hand.



On a side note, anyone know how many amps this set is supposed to draw? Right now mine is using almost 3 amps when I have it on 110 volts. I know there is a voltage selector on top of the transformer. I can move it and I put it in the middle, at three. I haven't found any information in the manual to what voltage each number is supposed to coordinate with.

[bandersen]

The label on mine says 300 watts so that would be about 2.7 amps at 110 volts.

[pendulum]

I removed the horizontal subchassis and ended up replacing a bunch of off resistors and it seems to have made a big difference! Vertical, horizontal hold and everything else is working great. As you can see in the picture however, there is some fold over at the bottom of the screen. I could get rid of it by adjusting the controls, but it reduced the size of the image too much for the mask. However, the one capacitor that I did not replace, 1ohm at 60 cycles 3v non-polarized, goes right across the vertical centering control. I did some math and using the capacitance reactance formula I figured this is about 2650uf. There also are a few resistors in the vertical linearity and height controls, so I will check those next. I also felt for how well the crt tested, I didn't have that great of brightness. However, there are also a resistor chain in the high voltage area which also may be off. Interestingly this revision of the chassis does not have a width control, so I will have to figure out what replaced it and check that area as well, as it stands the width is pretty close to correct for the crt size, but not perfect

[pendulum]

Well I must have made an error at some point. I was replacing the resistor chains in the high voltage area, along with the shorted ac cap and a few resistors on the pots. Now when I turn the set on and the flyback area kicks in something makes a horrible squeal. I was getting an image, and adjusting the horizontal sync control would change the noise, but I was not getting any image or sound like I did before. After turning the set on and off a few times I no longer get high voltage. I ohmed out the flyback and it doesn't appear that any of the sections are open, I'll have to check for shorts between the windings. My hope is that the problem is due to my replacing the resistors in the high voltage chain but not putting any insulating coating on them like was there before. I ordered up a can of corona dope and will see if that changes things when it arrives wednesday. The fact that adjusting the sync did effect the sound really makes me think there is some issue around the 6l6 and 1B3 tubes, though I don't know why this would also kill any sound or video.

[Electronic M]

Squeal is characteristic of the horizontal oscillator being off frequency (and sometimes off wave form). Here is what I would do: Get an oscilloscope connect it to the video output of a video source and get 2 synch pulses on scope screen at the same time, note the number of divisions between them, move the scope probes to the tv's H osc. and adjust for correct wave form and have the sweep waveform start and end with the same division width as measured between synch pulses.

The more I think about this, didn't the early Capehart/Farnsworth TVs use a separate HV system not based on the horizontal deflection? If so that squeal may be a HV circuit oscillator issue and not a deflection oscillator.

[Phil Nelson]

Originally Posted by pendulum

My hope is that the problem is due to my replacing the resistors in the high voltage chain but not putting any insulating coating on them like was there before.

I didn't put any corona dope on those resistors when I replaced them in my 661-P, and it seemed to work normally. I did insulate their leads with shrink tubing and I took care to make all solder joints in that area very smooth.

If arcing is going on, you may be able to see it by turning on the set and observing that area in a completely dark room.

If anyone wants to look at the factory service manual, it's available here:

http://www.myvintagetv.com/Apple%20P...e%20Manual.pdf

Regards,

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

[Eric H]

If it's not arcing then you probably got a resistor hooked in the wrong place, or the wrong value, been there done that many times.

I now take lots of high definition pictures of the chassis before I do anything, then if I'm in doubt I can check and see for sure where everything was hooked up and not rely on my lousy memory.

Now, what were we talking about??

[pendulum]

Well I powered it up in the dark and there was for sure no arcing. I only replaced a few components between when it was working and now, so I should be able to tell if any are hooked up wrong. I retested the 6l6 and the two 1b3's and found that one of the 1b3's was weak and the 6l6 has a screen grid short. The real question though, is did the 6l6, which appears to be the original, just happen to fail, or did I fry it trying to figure out what was wrong? Clearly it was working before if I was getting a real solid image. I will triple check my wiring tomorrow, but I really did very few repairs between the last powerup and this one, and only the resistor chain in the high voltage area, which is very straight forward. Either way it looks like I will have to get a new 6l6.

Edit: was checking the 6l6 again because the short would appear and dissapear. It seems when the 6l6 is in the tv, it gets super hot really fast. If I then take it out of the set and test it the short is there. If it has completely cooled the short doesn't really appear. Maybe it really was the tube that was bad, and by using it after 60 years it failed after an hour or so of test power ups.