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  #31  
Old 04-21-2018, 09:21 AM
Crist Rigott Crist Rigott is offline
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Quote:
Originally Posted by Electronic M View Post
The 1946-48 630 chassis have a reputation for bad mica caps in the IF...One of the only cases where I advocate recapping the micas.
Yes, I replaced those micas and the one coming from the tuner.
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  #32  
Old 04-21-2018, 03:37 PM
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Might be a good attack to take a spare 1500 pf and bridge the replaced ones one at a time. (?)
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  #33  
Old 04-21-2018, 03:42 PM
Crist Rigott Crist Rigott is offline
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Originally Posted by old_tv_nut View Post
Might be a good attack to take a spare 1500 pf and bridge the replaced ones one at a time. (?)
The micas in the IF stages are all 270pf. Are you saying to bridge each one with a 1500pf one?
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  #34  
Old 04-21-2018, 03:46 PM
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Sorry, I meant the 1500 pf bypass caps that are everywhere. Did you replace any of them? If not, that is even more reason to look for trouble with one of them.
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  #35  
Old 04-21-2018, 04:49 PM
Crist Rigott Crist Rigott is offline
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Originally Posted by old_tv_nut View Post
Sorry, I meant the 1500 pf bypass caps that are everywhere. Did you replace any of them? If not, that is even more reason to look for trouble with one of them.
OK, that makes sense. None of those were changed. There's a bunch of them. I'll let you what I find.
Thanks.
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  #36  
Old 04-21-2018, 05:48 PM
Crist Rigott Crist Rigott is offline
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OK, I jumpered each 1500pf bypass cap with some clip leads attached to a 1500pf mica cap. It wasn't as hard as I thought it would be. Still no joy. I'm suspecting the tuner.
Anymore ideas I could try?
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  #37  
Old 04-21-2018, 06:34 PM
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Even though the IF tubes test ok, I would try swapping them out to see if the symptoms change.

jr
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  #38  
Old 04-21-2018, 06:57 PM
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Originally Posted by jr_tech View Post
Even though the IF tubes test ok, I would try swapping them out to see if the symptoms change.

jr


I take it you found no hot spots that changed the behavior when touched.

How does the picture react as you turn the Picture control up and down? Do the streaks move? Or is there only a contrast change?
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  #39  
Old 04-21-2018, 07:09 PM
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Another question: what do you get if you disconnect the input signal? Can you get snow without streaking?
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  #40  
Old 04-21-2018, 07:09 PM
Crist Rigott Crist Rigott is offline
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Originally Posted by jr_tech View Post
Even though the IF tubes test ok, I would try swapping them out to see if the symptoms change.

jr
OK, I swapped out each one, one at a time with another NIB RCA 6AG5 that tested like new. Still no joy. Basically the same with each swap out. Good idea though.
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  #41  
Old 04-21-2018, 08:32 PM
Crist Rigott Crist Rigott is offline
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Originally Posted by old_tv_nut View Post
Another question: what do you get if you disconnect the input signal? Can you get snow without streaking?
When I disconnect the mica capacitor going to the 1st stage IF, the streaking goes away, but I also don't just get snow. I get some lines that I go away with the H. adjustment on the back. But never get any snow. When hooked back up, the streaking is there with the picture.
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  #42  
Old 04-21-2018, 08:50 PM
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I think he meant test pattern gen to tuner not tuner to IF...

If you have a B&K analyst or another set that uses the same IF freq, you could inject a signal into the IF and check it's function.
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  #43  
Old 04-21-2018, 09:09 PM
Crist Rigott Crist Rigott is offline
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Quote:
Originally Posted by Electronic M View Post
I think he meant test pattern gen to tuner not tuner to IF...

If you have a B&K analyst or another set that uses the same IF freq, you could inject a signal into the IF and check it's function.
OK. I'm uploading a video of what I have and what happens. It'll be ready shortly. I appreciate everyone's help.
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  #44  
Old 04-21-2018, 09:10 PM
Crist Rigott Crist Rigott is offline
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That was quick!

https://youtu.be/RG8w20No1Ew
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  #45  
Old 04-21-2018, 09:41 PM
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I didn't understand what it was you disconnected in that video. I did intend for you to disconnect the antenna input, not the IF.

Anyway, I think the next thing I would try (after disconnecting and reconnecting the antenna) is removing/swapping the RF amplifier (V1).
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