Quote:
Originally posted by Tubejunke
I have a 1958 Zenith Model C4007R Space Command with the 18C24Q chassis. The set has virtually no vertical sweep and only a hum for sound with no signal. I figured electrolytic trouble for sure. Well, I disconnected the leads to the cans and did an ohm meter "kick" test and found nothing unusual. No low resistance readings like I expected. I replaced several, but not all of the electrolytic caps and the set has not improved at all. I have replaced around 6 of the white tubular paper caps. I keep thinking I should easily run across some component with a way off reading like a shorted cap or something open but I just havent hit it yet. There are 2 black beauties in the vertical section that I havent touched. I dont think the small value caps would cause the serious ills of this set but I may be wrong. One thing I want to note is that there is a 5U4GB in place of a 5AU4. The set is producing DC, but could that tube cause some kind of short? A site that has sub info did not list the 5AU4 as a sub for the 5U4. They both have the same pin out so there should not be a short. I guess I'm hoping that some good folks out there are familliar with this chassis and its charicteristics. I know Zenith used this and variations of this for a few years. I notice that some scematics call for 5AU4 and others 5U4. There has to be some difference. I should be getting at least some life out of this set by now. It is more than half re capped. It will be a good one once I get it staightened out since it looked like the back cover had never been removed and all stock tubes. I figure low mileage. I also need a remote....
Thanks on advance!!
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I would also get rid of that 5U4GB and put the right rectifier tube (5AU4) in its place if your set calls for a 5AU4 on the tube layout chart in the cabinet, and/or on the schematic if you have one. I am amazed your set works at all with an incorrect rectifier, even if the pinouts of the two tubes are identical. If the 5U4 or any of its successors (5U4G, -GB, etc.) were meant to be used as substitutes for a 5AU4, it likely would have been listed as such on the website you mention or any tube substitution manual.
As to a replacement for the remote, I'd keep an eye out on ebay. Many times older remotes are listed there for very reasonable prices; some of them are even shown with a "buy it now" link below the opening bid. If you find one with such an option, I'd say grab it. Also, you can place an ad in any one of many antique radio/TV websites, such as Phil's Old Radios, asking for leads to one of these remotes (the site is also used for inquiries as to information or parts, etc. for antique TV sets).
Good luck. Zenith was a very good make of television sets in the 1950s and until they were acquired by Gold Star in the '90s. Your set is from 1958 and should work well for you for many years, once the restoration is complete.