Mitsubishi 6CT-333 "Trinescope" color projection TV restoration

[cj_reha]

I've got an interesting one for you folks. I imported this set two years ago from Japan and am finally getting around to working on it, and figured it'd make an entertaining thread.



This is a Mitsubishi 6CT-333 "Trinescope" projection color TV, using the RCA-developed technology of the same name; it produces a direct-view color picture using three 6" R/G/B CRTs and an array of dichroic mirrors - no mask required. As far as I can tell, this was the only example of a Triniscope-based consumer TV set ever sold. I have seen pictures of one restored by John Folsom last demonstrated almost 15 years ago, and another owned by Erich Loepke which as far as I can tell hasn't been run in about the same amount of time; I believe this is the third set of its kind in the States. I am very eager to get it running to see how the picture compares to its contemporaries



From my research, these sets were introduced as part of an effort to lower the costs of color TVs in Japan in time for the 1964 Tokyo Olympics. The 6CT-333 was introduced in 1963 at a starting price of 92,000 Japanese yen (approx. $3k USD adjusted for inflation/converted), apparently the first of its kind to break the 100,000 yen threshold. Although still extraordinarily expensive, its contemporaries cost two to three times as much, so they really did bring costs down! A similar set with a wider "viewport," called the 6CT-338, was released in 1965. It is electrically similar, though some differences are present as its schematic available on the ETF website does not quite match my -333. It appears despite their efforts, these sets did not sell well and were unceremoniously pulled from the market after "regular" masked sets came down enough in price. They never sold in the States, despite Mitsubishi apparently having considered it at one point - a 6CT-338 was exhibited at the 1964/65 New York World's Fair.

Onto my set. It is unfortunately in fairly poor cosmetic condition, but is at least complete with all knobs and trim pieces. It obviously spent a lot of time in a very humid environment, so I would imagine lots of parts replacement is in my future. The CRTs (3x 150LB22 R/G/B) test good, so I am confident the set is worth restoring in any case



Lots of power supply electrolytics. Cool to see early Nippon Chemi-Con caps. I will likely end up restuffing them to keep the set as original looking as is feasible inside.



It took me a little while to figure out what this is. It is actually a very high voltage paper capacitor across the anode supply - 2300pF rated for 20kV. It was disconnected at some point, so it is presumably bad. A long time ago I purchased a big lot of very high voltage film caps and I found a pair of 0.01uF at 12kV that should work fine in series to replace it.



The high voltage section is going to be a challenge to rebuild. Looks like I may actually need to remove the flyback and HV rectifier assembly to get at some parts underneath.



Here's the money shot. So many paper caps to change! Most look fairly easy to replace, since the backs of the boards are mostly accessible, but that vertically-mounted sweep section looks like a nightmare. The things I do for this hobby...

Anyway, I hope to have a lot more for you all soon. I'm in talks with a vintage TV and video hobbyist in Japan who has one of these sets, as well as the correct schematic diagram he is willing to send in the mail. It will make assessing what I have a hell of a lot easier.