I found some interesting read on early Japanese color TV, courtesy of Toshiba. Apparently Toshiba was the first to market them in Japan. First using a RCA picture tube and with their own design shortly thereafter.

Here's a link from Toshiba's Web Page:

Toshiba Early Color TV History

Here's a pic of Toshiba's Roundie Color TV:

http://www2.toshiba.co.jp/kakan/en/h...58tv_img01.jpg


Regards,

crooner

RCA Color monitor
 

This is the RCA color monitor inported from USA.

front pix

RCA Color monitor
 

back pix

That RCA monitor looks like a lot more robust design than the consumer sets...it appears to have a regulated power supply with 6080's and dual horizontal output tubes. Also the CRT looks like a later replacement (60's or 70's, judging by the modern RCA logo on it.)

Some RCA television monitors were actually built by Conrac, wonder if this color unit is actually Conrac. Their B/w monitors that I have, have extra special features such as a regulated power supply, HV regulator tube, etc. that no consumer B/W set has.

Wow !! That thing's as clean as a hound's tooth !! ita, I sure hope both of these bad boys are in a good home-preferably yours !! <grin> -Sandy G.

Well, in Bucharest, at the Universitatea "Politehnica" are some 2 Japonesee roundies, but not in working condition. One of it haves an 21CYP22A picture tube made by "R.C.A.". That roundie looks like an "Hitachi" CT-150.

Darn. One of those RCA studio monitors must be the ULTIMATE roundie. I bet they're as good as a modern TV, or darn close.

Anyone know where I can get one? :)

(wouldn't mind an old conrac B&W monitor either...)

Yeah, no kidding. Just look at all those tubes... Man, I'd love to find one of those. 'Course, I'd love to find a roundie period, but, one can dream :). I wonder how good the DC restoration on something like that would be. That's one thing that kinda bugs me with some cheaper sets, is the way the picture shrinks and expands, darkens and lightens as a function of the overall brightness of the image. Sure, I've added diodes and caps to help compensate, but even then it's hard to get good, crisp high contrast stuff on some sets.

I've been hunting a Conrac monitor for some time as well, haven't found a tube one on eBay, but some of the older solid state models show up from time to time. I'd love to be able to have a tube set that took composite video reliably. I've modified small black and white portables to take composite video, and used them as monitors with very old computers (Apple II, etc.), but it's a pain working around a way to safely direct-couple video into a stage in a hot chassis television set...

-Ian

The Conracs had very good DC restoration and regulation - and when looking at the tube count, you have to remember they had extra sweep functions for offsetting the V or H timing (or both), and expanding the V interval so you could see if the sync pulses were correct on your signal ("pulse-cross" setting). A real monitor would also allow you to turn the color notch filter off when the color was turned off, and had a phase-compensated peaking ("aperture compensation") control using a tapped delay line. No comb filter in these early beasts, though, and IIRC no I/Q demods either - just very good R-Y, B-Y.

[QUOTE=Jeffhs]It looks to me as if that set has a hi-fi audio system as well. I saw a separate chassis to the right of the TV chassis, connected to the main chassis by several cables which looked an awful lot like an amplifier, or perhaps it was the power supply. (On second glance, I saw several large electrolytic capacitors on that chassis; the line cord looks like it is attached there too). >>>

yeah just looks like the power supply and big can type caps are on it, and maybe the high voltage stuff under that metal cover.

@crooner: there's a problem with the TOSHIBA site... :no:

Damn! I bet that color monitor sucks up some serious wattage!

On a side note... have you ever wondered about the power cords used on vintage roundie sets? The cords usually look kinda wimpy considering the set uses 300+ watts!

Yes, Charlie, they sure do--and not only roundies. Every vintage color TV I've seen that draws 300 watts or more (including every old set I've owned over the years) has one of those thin-looking cords. Say what you will about the reliability of their TVs, but, IMHO, one of the best things Thomson (RCA) ever did with all of their sets was to put polarized AC cords on them, and with thick insulation along with conductors large enough to handle the current drawn from the line. However, it seems like overkill now (to me, anyhow) to put those thick cords on today's sets, as most modern TVs draw much less current than the old ones ever did. I had a Zenith 12-inch b&w solid-state portable, bought new in 1978, with a very thick and wired-in line cord (no interlock); my 1995 Zenith color set has such a cord as well, as does my living room set, an RCA (Thomson) 19" table model. The RCA draws 105 watts; the Zenith, 87 watts, and my small 12" Zenith (which I no longer have) drew well under 100 watts as well, but they all had/have thicker cords than the roundies and rectangular sets of 30+ years ago; the new ones are all hard-wired into the set as well. Even my bookshelf stereo system has a rather thick polarized AC line cord, despite the fact that it only draws 150 watts.

Ian, the way I always coupled anything into a TV set (or any kind of electronic equipment), whether or not it had a hot chassis, is to use a blocking capacitor in series with the circuit or instrument I was connecting to the set. Over thirty years ago, I learned a lesson I'll never forget when I tried to connect an oscilloscope to a color TV with a transformer-powered chassis, to monitor the video signal. I went across the contrast control, without using a high-voltage blocking capacitor in series with the lead to my scope's vertical input. Turned everything on and--whoops!--I heard a loud noise coming from inside the oscilloscope. By the time I heard that noise it was too late--the voltage across the contrast control in my TV had arced through the intensity control of the scope. Didn't really ruin anything (the scope still worked amazingly well for several years afterwards), although from that moment on, whenever I'd adjust the intensity control and the movable arm inside the pot contacted the burned area of the carbon resistance element, I would hear a noise very much like a rifle shot. :eek: :yikes: To this day I am amazed the scope didn't blow a fuse, or the power supply was not heavily damaged, the first time that happened. Hmmm. :scratch2:

Quote: "On a side note... have you ever wondered about the power cords used on vintage roundie sets? The cords usually look kinda wimpy considering the set uses 300+ watts!"

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Wimpy is right. Last night, or was it early this morning, a CTC2 (s/n B8000194), an early production chassis that I’m restoring, was powered up using a late-’50s cheater cord that has never been uncoiled since it left the factory. The cage is gutted so no HO circuit load exists, only the front end, the oscillators, video, chroma, sync sep., and so such.

It was on for about 30 minutes while checking voltages and stuff so I listened to audio from over-the-air ABC channel 7 from NYC while running the ABC video on an HDTV in NTSC mode. One of the things I did was check the power draw with a wattmeter – just short of 300 watts. A fully operational CT-100 is rated at 475 watts.

When I killed the power and removed the cheater cord from the CTC2 after the thirty minute run, that cheater cord was actually warm to the touch!

Pete