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#1
11-12-2014, 11:10 PM
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1956 Hoffman Colorcaster (56K Warning - Lots of Photos)
Howdy folks,
I don't often post here, but have been a Videokarma member for some time now, and read the postings religiously. In any case, I was the fellow that acquired the Hoffman Colorcaster in the Bay Area that was on eBay recently. I apologize in advance for the large number of photos, but I'm hoping this thread will serve as an excellent set of "notes" when I get going on the restoration, and (hopefully!) successfully complete it. The story of how exactly I came to acquire the set is a bit peculiar. My grandfather is a bit of an eccentric, and has a penchant for random gift-giving. A few weeks ago, he decided that all of his grandchildren ought to have new hunting rifles in time for the opening day of rifle season here in Michigan. I don't hunt however, and I only occasionally shoot trap and skeet, and he knew this. He happened to be at my home one afternoon in late October, and noticed that I was admiring the Hoffman on eBay. I briefly explained what the set was, and he muttered something under his breath, saying no more about it. The morning of Halloween, I received a call from my grandfather saying that he had been in touch with the seller, had purchased the set for $500, and that he was working with a shipping company to have it shipped back to the Metro-Detroit area. I then posted the set on uShip, and paid to have it shipped back to my home in Michigan, having felt that his incredibly generous gift was already much too great. It arrived the morning of Monday, November 10th, 2014 in a pickup truck driven by one Robert Giacometti of Buzz's Transport. He took the utmost care with the set, and even went to the trouble of purchasing a large metal bowl to place over the plastic bump out on the rear of the set. It arrived in Michigan precisely the way it was when it left Saratoga, California. Needless to say, I was thrilled with Mr. Giacometti's service, and would highly recommend him to anyone here. As soon as it was moved into the basement I began poking around. It's by no means perfect, but with little work it should be pretty presentable.  Here's the set with the back off:   The top of the chassis:  Rear apron of the chassis:  I quickly figured out how to remove the side panel that hides the underside of the chassis:  And then the panel covering the controls up front:  And then finally I removed the front safety glass and CRT bezel. It would look that the CRT is one of the later "grey screen" 21AXP22s:  It was at this point that I noticed the serial number sticker on the front of the CRT. The serial number on the CRT, and the serial number on the chassis match, thus indicating that the CRT is likely original to the set.   It was at this point that I decided to test the CRT. I noticed that the CRT base is Hoffman branded, but the tube is RCA built. It has a date code of 6 -13, which I believe means the CRT was built during the 13th week of 1956, between March 25th and March 31st.   I nervously connected my Beltron to the CRT, and was greeted by normal looking glowing heaters!  With 6 volts on the heaters, the CRT looked like a dud for a few mintues, when the meter movements suddenly sprang to life, pushing up toward the top of the scale. I allowed it to sit for a minute, and then looked at the life test. It took a full 15-20 seconds before the red gun (the weakest) began to fall!  Curious, I looked to find the lowest heater voltage the CRT would still "pass" at. I let the CRT cool for a number of hours, and then tested again inching the heater voltage gradually. At 3 volts I found pretty decent looking emissions on all three guns and an 8 second life test on the red gun.  I then turned out the lights and looked for any abnormal glow in the neck or near any of the elements. I found none, so I'm guessing (and hoping) that the tube is still under a hard enough vacuum to operate correctly. 
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#2
11-12-2014, 11:23 PM
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From here I turned my attention to the schematic found here.
And the tube location chart found here. After examining a number of other schematics from other early 21 inch color sets, it looks to me to have the "RCA Licensee" circuit, but with the high voltage section more closely resembling that of the 21-CT-55, and a few tube types changed. Perhaps Hoffman received an excellent deal on the 6K6 used as the audio output, and opted to use that instead of the 6AQ5 used by other manufacturers. In any case, if anyone has a copy of RCA Licensee Bulletin No. 962 (dated September 16th of 1954), I'd love to see it. I'm curious as to what exactly RCA specified in that circuit, and where Hoffman deviated from that. For comparison sake, the schematic of the Sentinel IU-816 bears some very striking similarities, especially in the IF strip and color circuits. Any info on the RCA licensee circuit would be greatly appreciated.  I guess this is it for the time being. I have an ongoing, perplexing medical issue that will very likely leave me hospitalized for some time. I hope to be back home and digging into the set by Christmas, but I'm not holding my breath... - Ben Last edited by benman94; 11-13-2014 at 10:05 AM.
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#3
11-12-2014, 11:39 PM
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What model number is it? I have a NOS Hoffman remote kit for color TV's on eBay right now. You can see the models listed there.
http://www.ebay.com/itm/301383354181...84.m1555.l2649
__________________
"It's a mad mad mad mad world" !! http://www.youtube.com/user/mwstaton64?feature=mhee
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#5
11-12-2014, 11:46 PM
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Looks like just 7000 series sets. Sorry
__________________
"It's a mad mad mad mad world" !! http://www.youtube.com/user/mwstaton64?feature=mhee
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#6
11-13-2014, 01:08 AM
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Wow, a Colorcaster with a good 21AXP22 -- Santa came early this year!
I really like that side service panel. What a thoughtful feature. Phil Nelson Phil's Old Radios http://antiqueradio.org/index.html
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#7
11-13-2014, 01:29 AM
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What a fantastic set -- I'm looking forward to seeing your progress on it.
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#12
11-13-2014, 03:13 PM
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Quote:
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#13
11-13-2014, 07:20 PM
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Great scroe! I would have bid myself, but in truth I'm tired of shipping sets all over the place. Guess the only way I'd get involved is if one popped up in my backyard.
__________________
Evolution... 
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#14
11-13-2014, 08:36 PM
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Nice gift! Sure makes the Philco cathedral I got for my birthday pale in comparison...
That can't be a Hoffman (QU)"EASY-VISION" CRT because it is not a GREEN face 21AXP22  ...Yup, definitely an RCA fake. 
__________________
Tom C. Zenith: The quality stays in EVEN after the name falls off! What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4
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#15
11-13-2014, 08:45 PM
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That should be an excellent project. I hope your health issues do not keep you away too long.
__________________
Chris Quote from another forum: "(Antique TV collecting) always seemed to me to be a fringe hobby that only weirdos did."
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