#46
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Also, the power-up a year ago could have stressed parts such that another power-up now would blow things that didn't blow a year ago. You are going to re-cap it anyway, you might as well do that (at least the electrolytics, etc.) first.
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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." |
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#48
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I've started to test the tubes but only got about 1/3 of the way through. Until I get my reading glasses it's a bit tiring.
Besides the CRT having tested so strong, all of the tubes I've tested so far test like new, even the 6T8 of which I usually have trouble finding a strong one. They also are all RCA with date codes in 1957. It seems like they're the original tubes. I don't think they watched this set much. The 6BK4 seems to be the one without lead in the glass. Guess I'll make sure the cover is on the HV section when I ever get around to powering this set up. Here's an interesting article on how to use the 6BK4 to generate x-rays. John |
#49
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In the end I decided to follow jr_tech's advice.
I removed the 6CB6 HOT and gradually brought it up on a variac monitoring the power. It was drawing 380 watts at full voltage which is about 40 watts high. Just the variac draws 10 watts so it might be closer to 370 watts. After reinstalling the 6CB6 and hooking up my laserdisc player I had a raster and good sound! The raster is high and to the left. When I adjust the horizontal hold and get it close to locking in it goes into something that looks like barkhausen. The power draw was down to 340 watts during this. I don't understand why, maybe having a signal helped. I thought having the HOT tube in would make it draw more. Although it's difficult to tell in the photo, when I looked at the bright dots caused by the closed captioning, the convergence wasn't very bad. I thought it would be a lot worse with the raster positioned like it is. With no signal I get a very uniform white screen. It looks like a simple recap and checking for bad resistors will make this an easy restore when I get around to it. Oh, cats... All three of mine wanted to help. This made it quite a bit more difficult. John Last edited by jeyurkon; 04-09-2010 at 12:01 AM. Reason: Added comment |
#50
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Great News !
It looks like nothing is seriously wrong with the set ! Now the big decision... repair the problems or do a total re-cap. jr Yes! I have also noticed that cats can be great little helpers. Last edited by jr_tech; 04-09-2010 at 12:46 AM. |
Audiokarma |
#51
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Phil |
#52
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Sweet I need to get a cat!
I agree with Phil. I had been doing slash and burn on all capacitors, but lately I'm just doing the electros. first to see how it runs. Then, going after the bad caps one by one. |
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I was reluctant to post this, but guess I shouldn't be.
I don't have as much experience as you guys, but my experience so far has been that: Electrolytics, 50+ years old, that pass value, leakage and ESR after reforming and maintain those after letting rest a few day, are very reliable. I've not had a failure yet after years of use. I use my Hammarlund HQ-160 at least weekly and I've never recapped it. It's about 52 years old. I wasn't very old, 12 maybe, when it was given to me by a gentleman who was dieing of stomach cancer who knew my interest in electronics. Paper capacitors on the other hand have nearly all been bad and I've replaced all of those in radios and the Sylvania I've worked on. Of the micamold (real mica variety) nearly 50% have been bad. Other brands have been o.k. Polystyrene, I've only experience with one that is from 1950 but it is good. I had one bad silver mica in an IF transformer. I had one bad disc ceramic. It was actually o.k. I just didnt' like using a ceramic without the coating and with 10% of the disk broken off. When I do replace electrolytics, I've decided to use 105 C ones. I've had to replace too many 85 C ones in modern electronics. I had originally planned on replacing all of the electrolytics in the Sylvania, but when the replacement electrolytics didn't test as well as the old ones I decided to keep them. I had ordered the electrolytics from one of the inexpensive online suppliers and I think they're the 85 C ones. I'm happy with their film caps, just not the electrolytics. John |
#54
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Nice going John! Looks like you have a winner! Great acquisition, especially with the good 21AX. Once you get hooked on color you might never go back. I am having trouble trouble getting excited about restoring the many B&W sets in my stable, now that I have so many color sets that need my attention.
So many sets, so little time! And I am retired to boot.
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Vacuum tubes are used in Wisconsin to help heat your house. New Web Site under developement ME http://AntiqueTvGuy.com |
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