David Roper
06-05-2009, 06:06 AM
http://tvhistory.tv/1951-DeForest-20in.JPGhttp://i163.photobucket.com/albums/t303/ISXX/americantv.jpg
The model number is known actually, it's American Television 2001A.
I've had this set for about four years. In the time since I acquired it I have learned that American Television was headed up by mechanical TV pioneer U. A. Sanabria, whose Western Television had manufactured the Visionette, Empire State and other 45-line triple-interlace TV models back in the mechanical days. In the 50s, his sets were variously branded American, DeForest and DeForest-Sanabria.
It came to me with the base whacked off of the CRT (the cathode lead came off with it, snapped flush with the glass), a condition which kept it in the back of the to-be-restored queue until I recently acquired an 8" test CRT. I did not, however, acquire a schematic. Instead I traced out my own. (http://i163.photobucket.com/albums/t303/ISXX/American2001A.jpg) In doing so I discovered just how unusual this set really is.
There are four distinct B+ lines, only one of which comes off the conventional source. It measures about 365 volts. There also is a 425 volt boost line--nothing unusual about that as it serves the vertical sweep section, except it also provides focus voltage for the CRT. Another source is the rather unconventional 150 volt line, a circuit which leaves a guy such as myself scratching his head wondering what's missing, as this line has no apparent source. But the fourth B+ line is really something else. Trace it back far enough and it does connect to the main B+ which accounts for it measuring within a couple volts of 365. But this fourth line, which provides plate voltages for several tubes including audio and video output, first passes through the flyback and yoke.
:wtf:
So the process was: trace the circuit, rub my eyes in disbelief, confirm that what I drew is in fact how it's wired, move to next circuit, repeat.
With its sparse count of 17 tubes on top of the chassis, I was always skeptical of how well it would work. Once I got a got a look underneath the chassis I was skeptical IF it would work. I'm very pleased to report that, for all the set's eccentricity and economy of parts, Sanabria was no Muntz.
http://i163.photobucket.com/albums/t303/ISXX/img_0186_1.jpg
That's an off-air capture using rabbit ears (for close to the last time) :tears:
The set shows absolutely no retrace whatsoever. Even when running on an RF modulator it is not the least bothered by white/hi contrast scenes and has as minimal sync buzz as any set I've restored.
The next step is to determine whether the CRT is salveagable and, if not, where I might find a good one.
http://i163.photobucket.com/albums/t303/ISXX/American2001A_rsz.jpg
The model number is known actually, it's American Television 2001A.
I've had this set for about four years. In the time since I acquired it I have learned that American Television was headed up by mechanical TV pioneer U. A. Sanabria, whose Western Television had manufactured the Visionette, Empire State and other 45-line triple-interlace TV models back in the mechanical days. In the 50s, his sets were variously branded American, DeForest and DeForest-Sanabria.
It came to me with the base whacked off of the CRT (the cathode lead came off with it, snapped flush with the glass), a condition which kept it in the back of the to-be-restored queue until I recently acquired an 8" test CRT. I did not, however, acquire a schematic. Instead I traced out my own. (http://i163.photobucket.com/albums/t303/ISXX/American2001A.jpg) In doing so I discovered just how unusual this set really is.
There are four distinct B+ lines, only one of which comes off the conventional source. It measures about 365 volts. There also is a 425 volt boost line--nothing unusual about that as it serves the vertical sweep section, except it also provides focus voltage for the CRT. Another source is the rather unconventional 150 volt line, a circuit which leaves a guy such as myself scratching his head wondering what's missing, as this line has no apparent source. But the fourth B+ line is really something else. Trace it back far enough and it does connect to the main B+ which accounts for it measuring within a couple volts of 365. But this fourth line, which provides plate voltages for several tubes including audio and video output, first passes through the flyback and yoke.
:wtf:
So the process was: trace the circuit, rub my eyes in disbelief, confirm that what I drew is in fact how it's wired, move to next circuit, repeat.
With its sparse count of 17 tubes on top of the chassis, I was always skeptical of how well it would work. Once I got a got a look underneath the chassis I was skeptical IF it would work. I'm very pleased to report that, for all the set's eccentricity and economy of parts, Sanabria was no Muntz.
http://i163.photobucket.com/albums/t303/ISXX/img_0186_1.jpg
That's an off-air capture using rabbit ears (for close to the last time) :tears:
The set shows absolutely no retrace whatsoever. Even when running on an RF modulator it is not the least bothered by white/hi contrast scenes and has as minimal sync buzz as any set I've restored.
The next step is to determine whether the CRT is salveagable and, if not, where I might find a good one.
http://i163.photobucket.com/albums/t303/ISXX/American2001A_rsz.jpg