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  #16  
Old 08-27-2017, 05:57 PM
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Oh my, yes. The stereo will blow you away. 15" woofers and exponential horns. Unfortunately, the color on the set just went out. I watched it for about 30 minutes, and it just instantly went to black and white. I'm thinking the problem is in one of these tubes.
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Last edited by TUD1; 10-20-2017 at 11:02 AM.
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  #17  
Old 08-27-2017, 09:31 PM
consoleguy67 consoleguy67 is offline
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Also, check the tuner.
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  #18  
Old 08-27-2017, 10:35 PM
old_coot88 old_coot88 is offline
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While watching the screen in a mirror, give the suspect tubes a gentle tapping and wiggle 'em in their sockets.
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  #19  
Old 08-27-2017, 10:55 PM
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I'll do that tomorrow.
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Last edited by TUD1; 08-28-2017 at 08:52 AM.
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  #20  
Old 08-28-2017, 01:07 AM
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If it's a 70s set it's most likely to be VERY early 70s with a T940 chassis. If late 60s, probably T933.

I guess we'll never know. I'm out of here.

Last edited by Jon A.; 08-28-2017 at 04:35 PM.
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  #21  
Old 08-28-2017, 08:44 AM
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Quote:
Originally Posted by old_coot88 View Post
While watching the screen in a mirror, give the suspect tubes a gentle tapping and wiggle 'em in their sockets.
Reminds me of the Zenith I grew up with like in my avatar. When it would go off-channel or vertical/horizontal would lose lock my father would stomp his foot on the floor to straighten it out for a while.
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  #22  
Old 08-28-2017, 02:00 PM
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Got the color back, but I expect it to fail again soon. This set is being extremely temperamental.
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  #23  
Old 08-28-2017, 05:33 PM
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Can you show shots of the control panel and the record changer? Nice save, I hope you enjoy it as much as I would.
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  #24  
Old 08-28-2017, 06:05 PM
Bill R Bill R is offline
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Buy a box of those 6GH8A tubes. They will come in handy.
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  #25  
Old 08-28-2017, 06:36 PM
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This sucks. I reflowed a bunch of cold solder joints, got the color back, and I *think* it's here to stay now. However, in order to get the chassis out, I had to cut a shielded wire (I now realize) and just soldering it back together isn't good enough. Now I've got a whole bunch of horrible 60 Hz hum in the audio.
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  #26  
Old 08-28-2017, 07:11 PM
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Quote:
Originally Posted by TUD1 View Post
This sucks. I reflowed a bunch of cold solder joints, got the color back, and I *think* it's here to stay now. However, in order to get the chassis out, I had to cut a shielded wire (I now realize) and just soldering it back together isn't good enough. Now I've got a whole bunch of horrible 60 Hz hum in the audio.
The moral of the story: unplug wires, instead of cutting, and if there is no plug unsolder the wire and add one....If you can't reach the solder joints it probably means the makers wanted the stuff on both ends to be removed as a pair, or your missing something important.

I'm guessing it was an audio cable you cut? Try to see circuit wise what is on both ends and how it connects. Perhaps it can be replaced easily with some modern cable you have on hand.
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  #27  
Old 08-28-2017, 09:35 PM
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Now I feel extremely stupid. Turns out the wireS did plug in, and if I had realized that, I could have saved myself about two hours. HOWEVER! The color is STILL intermittent! I'm at my wit's end with this thing. I cleaned every tube socket, checked every tube, and reflowed every solder joint in the color circuit. I'm at a loss.

Update. The color is working again, but I'm scared to watch the set for fear of it breaking again.
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Last edited by TUD1; 08-28-2017 at 10:47 PM.
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  #28  
Old 08-29-2017, 12:02 AM
old_coot88 old_coot88 is offline
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Have you tried turning the color killer control? If it's set just 'under the threshold', it could be cutting the chroma on and off.
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  #29  
Old 08-29-2017, 08:54 AM
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If you can get the intermittent to hard fail or better yet to be predictable troubleshooting becomes easier. Run it with the back off. Look for tube heaters that are glowing dimmer when color goes out (I've seen tube heaters be intermittent in the socket and other wired things). If that don't work try to monitor voltages and waveforms/amplitudes in the color stages and see what changes and where it originates.

It is easiest to do signal tracing when you have a working set to compare to....This situation allows you to do that without a needing a second set.
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  #30  
Old 08-29-2017, 09:51 AM
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Quote:
Originally Posted by old_coot88 View Post
Have you tried turning the color killer control? If it's set just 'under the threshold', it could be cutting the chroma on and off.
I found that if I turn the color killer all the way up and down a few times, sometimes, the color will come back.
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