|
|
|
|
|
#1
12-10-2003, 11:29 PM
|
||||
|
||||
|
Virgin 1958 Space Command 400???
I recently brought home a Zenith Space Command model C4700R. Like a dummy I plugged her in to the wall and didnt bring her up slower with my series 100w lamp jig. What I got was a good loud hum with a very healthy horizontal line. Obviosly the set had cap issues. Upon inspection of the uncommonly clean chassis I noted that all tubes were of the same vintage and O.E.M. I believe that this set has gone virtually its whole existance without use. I guess there are a few out there that for what ever reason were never used. Its kind of exciting to think that a re cap job would give me a good daily use antique TV. With a 24" screen this beauty would be just as good to look at as anything else. I do not have a remote for this set and if anyone has an extra I am willing to buy or trade. I have a bunch of N.O.S. flybacks and yokes to get rid of. Any stories and helpfull hints concerning this Zenith will be highly apreciated.
|
|
#2
12-11-2003, 06:17 AM
|
||||
|
||||
|
If you can get hold of another ultrasonic remote transmitter you can often retune it to get at least some of the functions to work on the set...some may work already with no adjustments to the xmtr.
I only use the series lamp jig with a shorted set to try and diagnose shorts, have not had luck with re-forming old caps. I think it is better to just replace all of them. (paper and electrolytic).
|
|
#3
12-11-2003, 12:24 PM
|
||||
|
||||
|
Still don't get the big deal about caps.
I've fired-up sets that have been unused for decades, sometimes with good results, sometimes without... But I've never had any disasters. The Zenith's shown below have all the OE caps, except one in the vertical section of the portable (and that was only to fix the occasional vertical roll). Why not start with the most common problem, vertical output tube; rather than a shotgun approach of cap replacement? If your set truly has low hours, it may be a cap problem, but a tube swap takes less than a minute!
Last time I made a post like this, I swear that I got two PMs from posters (who asked me not to reveal their names) who basically said shotgun cap replacement was a waste of energy, especially for an occasional use set. You would think I was advocating an overthrow of the government... I could feel their fear of coming out of the closet!! I don't mean any disrespect, especially to the only board I've ever been on that was "flame-free" but I take more of a "if it ain't broke don't fix it" approach. Don't get me wrong, I will tear into stuff for even a minor infraction. On the subject of the SC400, I got a remote for mine from Ebay about two years ago. The same 50s remote will control all the functions of my late 70s Chromacolor set (and vice versa). (Ignore the newer set.. It just happened to be in the picture at the time!)
|
|
#5
12-11-2003, 01:12 PM
|
||||
|
||||
|
I can see your point...Of course it is best to check for weak tubes first, and I usually don't replace all electrolytics, only ones that appear bad, but I do try to replace all paper caps in pre 1960's sets. It is a lot easier to troubleshoot problems in the sets when you know you are not running into problems such as excess leakage in capacitors upseting bias voltage, etc. I also feel like the reliability of the sets are improved with new caps. In radios and amplifiers the sound quality is always improved when I get rid of those old paper caps.
|
| Audiokarma |
|
#6
12-11-2003, 01:21 PM
|
||||
|
||||
|
I didn't used to be so religous about changing the caps, but got tired of having to keep pulling the chassis for one more bad one. I actually enjoy recapping, for the most part. I will usually try a set first & if it works fine I will put off recapping for a long time. Its easier to get away with that with stuff from the 60s than the older gear. I havn't found a tv from 50 or before that worked right without caps-black beauty disease.
__________________
Bryan
|
|
#8
12-12-2003, 01:36 AM
|
||||
|
||||
|
Help Weed Out Bad Caps
Carmine mentions checking/changing tubes as opposed to a "shotgun approach" of cap replacement. Dont worry man I put up a fairly high resistance to replacing caps. I check everything else first. I have become confused trying to test caps. What I mean is there have been many times I have disconnected one lead from the circuit and used an analog ohm meter to watch the needle sweep to zero and fall back to a high resistance reading and assumed the cap was ok because the needle didnt stop at some low resistance. In later frustration I change the cap and the problem goes away. This is basically what the books say about testing caps. I have a digital meter with a capacity feature that I'm not really sure how to use. Of course I realize that the digital job will give me a reading of the value of a component. I really wish someone could give advice on a good way to know if an old cap is really good. Anyhow the reasons I jumped to the cap conclusion is the fact that I had replaced the vert tube and got no result, also the hum in the speaker, and no signal. Kinda has capacitor trouble written all over it. My frustration with finding faulty ones short of replacement made me think of replacing them all.....
|
 |
|
|
Hybrid Mode
