japanese roundie

[RetroHacker]

Originally Posted by nasadowsk

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

[Jeffhs]

Originally Posted by RetroHacker

...it's a pain working around a way to safely direct-couple video into a stage in a hot chassis television set... -Ian

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. 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.

[Pete Deksnis]

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!"

----------------------------

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

[Telecolor 3007]

"R.C.A" 21-CT-55 eats "only" 525 watts!