#46
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Quote:
Quote:
Please do not scrap that Zenith! Tom C. |
#47
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Quote:
Thanks for the encouragement!
__________________
"Face piles of trials with smiles, for it riles them to believe that you perceive the web they weave, and keep on thinking free" |
#48
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I did some probing and found the 410V derived from the 420V boost was only around 350V. I measure R78 and it was high - about 8K.
I replaced that and got full height even though the 410V line was still low at 380V with 8V P-P of ripple. Unfortunately, while I was adjusting various controls the picture starting breaking up. Then I completely lost the video and sound. I still have a good raster and all the controls respond. I've already checked the tubes and replaced a weak 3CB6. The 5J6 is a little weak too, but I couldn't find a replacement so I tried a 6J6. That didn't make any difference. I'll fire up my 1077B and try injecting signals at various points in the RF/IF stages. I hope it's something simple. |
#49
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I fixed the set (again)
It took a while, but eventually I found this bad resistor hiding under a coil That supplied +130V to the 2nd IF stage. That's right before the detector so no picture or sound. I replaced it and got the picture back but no sound. More troubleshooting revealed the coupling cap between the volume control and audio output tube had a broken lead. I quickly soldered that back on sound was restored Better yet, I have full vertical although the control is near the edge of it's range. I'd still like to find out why the 410 line is a little low When I first popped this set open, I found a 1.8K resistor someone had added between the 410 line and 10uF filter cap. That seemed odd and I removed it. It might be worthwhile to put it back. Doesn't seem like adding a resistor is going to increase the voltage though. Also, replacing the weak 3CB6 increase the gain and I have a brighter picture. Odd that it and the 5J6 test weak now when they were good a couple weeks ago. Maybe running this set for a few hours drained what life they had left ? The picture is off-center to the left a little, but I can take care of that by adjusting the ion trap magnet or centering magnets. Last edited by bandersen; 03-01-2011 at 04:10 PM. Reason: corrected typos |
#50
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I put the set back together and it's playing well.
Sometime later this spring or summer I plan on repainting the cabinet. I think I'll try using electrolysis to remove the rust and hopefully the paint too. |
Audiokarma |
#51
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Tubejunkie since you did not want to go off topic I sent you a PM with some suggestions.
Tom C. |
#52
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I masked off some of the orange on my paint test subject and put on a few coats of "Ivory Bisque" followed by a clear coat of the engine enamel. I think it looks great and is very tough
I examined the cabinet and it appears they also painted the whole cabinet orange first, than applied the white. Odd - I would have done it the other way round |
#53
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Here's one for sale in very, very nice condition! http://cgi.ebay.com/Vintage-1957-2-T...-/290541493996 (no affil.)
Is this plaid cover original ? It sure looks like it. |
#54
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That is an original cover, I've seen ads with those in them.
I Picked up some aftermarket plastic covers on eBay in Red and Pink for my Hotpoint/GE 9" and 14" sets. They were NOS with the boxes but they had shrunk somewhat and it was a bit difficult to get them on the TV's The Emerson 1232 8" Portable also had a zippered carrying case, I have one but it's falling apart at the seams and is stiff with age. |
#55
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maybe they used those covers as a work-around for the hot chassis issues those sets had.
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Audiokarma |
#56
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Green T-103
I have just had a mint condition T-103 as a gift: as all tv has switched to digital, few enthusiast want to mess up with VHF modulators.
I think it's a very rare set to find in Italy: actually I've been told that it belonged to a wealthy US family living in Milan. In 1956 few people owned a TV, (they costed like 5-6 month wages) and no one was already caring for a kitchen - or holiday house - set. The body is near perfect, inside is very clean. I've been told that it works, but I want to check it for leakages first, using a variac and isolation transformer. Export sets like this have an additional auto-transformer to adapt to different line voltages, 220 included. And of course they are tuned to the 625 lines - 5.5 MHz intercarrier used here. I have a schematic but not the SAM's service manual ... Thanks for all the advice on this thread, I hope to begin working on it soon ! |
#58
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A good source for dropping capacitors is old ceiling fans, you'll find them in the switch housing.
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#59
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The green T-103 I'm working on, as I said, was sold in Italy. It differs from the US market models in the power supply (see schematics). It's got an autotransformer. This increases the weight, but has a great bonus: it gets rid of the 20W resistor with an 85V tap for the heaters !
Additionally, it provides 220V for the B+, so that a voltage doubler circuit is not necessary, and the 2 selenium units are wired together. I'm slowly conditioning the capacitors with a Variac now ... |
#60
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We've finally climbed out of the 30s so it's time to repaint this cabinet
I picked up a tub big enough to submerge the cabinet. I filled it with some water and Washing Soda (Sodium Carbonate). I used a 2A/10A battery charger for the juice and a big old cold chisel for the sacrificial iron. I was really surprised that the paint was bubbling off in only 30 minutes! A few hours later and it was all off It worked even better on the orange paint. I had some gray and maroon primer on hand and used appropriately. Now it's time to pull the chassis and dunk the rest of the cabinet. Last edited by bandersen; 04-05-2011 at 02:12 AM. |
Audiokarma |
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