#271
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#272
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I may look into it, but first I have to figure our which cabinet makes the most sense.
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Evolution... |
#273
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Here's the 9-T-79, pretty isn't it? Finish is almost perfect, I almost want to get it working as a B&W set and leave it alone...
The options I can see with CRT mounting on this cabinet are: Remove 19" mask, mount 16" one on a piece of plywood, paint the same off-white color, then install into the cabinet. Create wooden mounting for CRT, install in cabinet. Somehow modify 19" mask to accept 16" tube.
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Evolution... |
#274
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Nick,
That is one awesome looking cabinet, I would say that it would make for an awesome way to display the prototype set. Im glad you are so dedicated to bring it back to life. Maybe it will be good in time for next years ETF and you could bring it and talk about it Keep up the great work, Matt |
#275
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I think you can have it both ways: Do no damage to the B&W cabinet. If you still have the CRT bracket that was on this set when Harry Poster had it: http://earlytelevision.org/images/RC...1-poster-1.jpg Since the prototype apparently has no mounting brackets, simply slide it into the cabinet with the original 19 B&W inch mask in place (or possibly a reproduction mask not so thick. You might have to fabricate a removable wooden "shelf" to raise the chassis to match the apparently higher positioned CRT in the B&W cabinet.) It is my theory that the RCA prototype cabinets were made with oversize masks to accommodate multiple test chassis, and the front support bracket on the chassis was actually designed to be visible. I know it is risky to assume color from a B&W photograph, but look closely at this B&W photo of an RCA color prototype from nearly the same era as your monitor: http://earlytelevision.org/images/RCA_model3_front.jpg Or this earlier color photo with the front of the TV is in deep shadow. Note the apparent double masks: http://earlytelevision.org/images/1950rca16inproto.jpg Or this RCA prototype, which is labeled a converter, but looks like it has a tuner: http://www.earlytelevision.org/image...Converter1.jpg James |
Audiokarma |
#276
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Not likely. RCA was always using parts from current stock, even when they designed the prototype colors tubes. The mask that came with the chassis is just a run of the mill 16GP4 mask, which makes sense since I've heard they simply modified a metal shell B&W tube with color guts. Indeed, the mask it came with is identical to the one in the TC168.
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Evolution... |
#277
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I'd keep the tube mounted to the chassis as it was, leave the cabinet the same, and make an inner mask to go behind the 19" one in the cabinet and keep most or all the front chassis CRT support out of sight. This would keep both the chassis and cabinet virtually unmodified so if a cabbinet you like better becomes avalible etc. you can put every thing back as it was easily and not have to (un)modify the proto set at all.
Double, triple or even quadruple masks don't bug me (they can even look awesome IMO in some cases) at all as long as they are executed well, and one can argue that 15GP22 sets were at least visually like that due to the mask in the tube. Just thinking out loud. Tom C. |
#278
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Had some spare time today, so I made a new label for the proto CRT. The old one was ripped, so I found a picture of one on the web and inserted the part and serial numbers on to it. I carefully removed the old one with a razor blade, then applied the new one with clear tape. In case it gets melted, I put another larger one on the bell.
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Evolution... |
#279
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That was a great job of making the replacement label!
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Chris Quote from another forum: "(Antique TV collecting) always seemed to me to be a fringe hobby that only weirdos did." |
#280
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Began work on the power supply, it was on hold today till the Packers got done whooping on Duh Bears. Go Pack, Go!
Below you can see the setup for reforming the NOS capacitors I got from Bob G, he had a drawer full so I was able to select the best suited ones. It consists of the power tranformers, rectifiers, a current meter between the cap and rectifier and a VTVM at the cap. This way I can measure the current the cap is drawing as it reforms, and the potential at the cap to make sure I do not exceed rated voltage. I got some nice tall unused cans from Bob: one with 80uf @ 475VDC and 160uf @ 250VDC sections, the other with 80/30/4uf @ 475VDC and 500uf @ 35VDC sections. There are 2 others that were used pulls, if I need those I will likely restuff them with new ones I have laying around. These unused caps are forming up very nicely, neither one pulled more than 1ma during the forming process and stayed cool as a cucumber. Real test is if I am able to apply full rated voltage right away tomorrow morning, if they hold that I will call them good to use. The power supply is being built pretty much the same as any other RCA one with a pair of 5U4G's, 80uf cap input filter, choke, then another 80uf cap (inductive pi filter). That's where 385VDC B+ will come from. Then there will be whatever resistor value is required to get a 285 volt rail, followed by another filter section. If I need another lower voltage rail, it will just be another resistor and cap. Tomorrow after work, I will likely build up the harness to go between the supply and main chassis. It's very tempting at that point to power up the tuner and IF sections of the proto chassis, just to see if an RF input signal will pass to the detector. If I do try and it does go through, I will then move on to the other circuits and see what they do. I know most people don't like the 'brute force' method, but it's the fastest way to figure out the relative health of circuits. With tubes you're not as likely to blow something as with transistors, so I don't anticipate any fireworks. Hopefully I can get a staircase to show up at the detector, it would be a very good first sign.
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Evolution... Last edited by miniman82; 09-26-2011 at 12:30 AM. |
Audiokarma |
#281
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it's alive....sort of
Most improtant update so far, besides the CRT still being under vacuum: the proto chassis passed it's first signal tonight!
Yes it was a hacked together mess, no it was not pretty. But it did the trick! I cobbled together the B+ supply, powered only the filaments of the tuner and IF, then slowly increased the variac till 200 volts showed on the meter. Then I glanced over at the scope, and what do I see? A messy luma staircase at the grid of the 1st video tube! It looks like hell, but the important thing is it's there. There was no AGC voltage applied, so that's probably why the signal was all dirty. Work today sucked, but this more than makes up for it. Tomorrow I figure I'll try to add some AGC voltage since I know where the AGC buss is located, to see if I can't get the signal to look better. Hope it works.
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Evolution... |
#282
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Nick,
Thats great to see some for of life out of that set Keep it up man, doing a great job, with how it is going I fully EXPECT to see this at next year's EFT running off of one of Darryl's converters. Matt |
#283
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Great to see historically important circuitry come to life. Interesting photo too -- a CTC2 chassis lurking there behind the proto chassis.
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#284
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That's what I call a professionally decorated room. I would feel at home there! Glad the critter is opening it's eyes! My dining room table is used more as a repair bench than a dinner table!
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#285
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Glad to see that chassis still has some life!
Another historic moment indede. Last edited by Electronic M; 09-28-2011 at 12:16 PM. Reason: typo |
Audiokarma |
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