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  #16  
Old 01-11-2019, 11:36 AM
Jeff Jeff is offline
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Quote:
Originally Posted by zeno View Post
You may try lifting pin 12 & see if you get 1-2V P-P of video on the
pin. You could also try hooking in composite video at TP 6 from a DVD. Just
be sure to use isolation !

73 Zeno
LFOD !
Just for good measure, I replaced the IF amp IC again, this one was a completely different brand and seller, and it does the same thing. Pulled pin 12 and there was just a flat line all the way down to the 100mv range. The thing is, when I inject a composite video signal straight to the video amp, It basically does the same thing with it's color situation, but I just assumed this was because composite is only 1v pp and the circuit expects 2v pp.
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  #17  
Old 01-12-2019, 09:17 AM
kf4rca kf4rca is offline
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You should have seen something. Its probably not a problem with the IF amp.
Hope you put a socket in there.
Lets back up. Do you have ALL your supply voltages?
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  #18  
Old 01-12-2019, 06:58 PM
Jeff Jeff is offline
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Quote:
Originally Posted by kf4rca View Post
You should have seen something. Its probably not a problem with the IF amp.
Hope you put a socket in there.
Lets back up. Do you have ALL your supply voltages?
140v rail is 142v, pin 3 (155v) is 159v, 22v rail is 24v, 12v rail is 12v, 35v rail is 36v, and I can't think of any others.
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  #19  
Old 01-13-2019, 12:47 PM
kf4rca kf4rca is offline
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Are you able to get sound thru to the speaker?
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  #20  
Old 01-13-2019, 08:47 PM
Jeff Jeff is offline
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Originally Posted by kf4rca View Post
Are you able to get sound thru to the speaker?
Yes, very loud static when no station is tuned in, and with a signal tuned in, sound is fairly clear with normal volume.
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  #21  
Old 01-14-2019, 10:09 AM
kf4rca kf4rca is offline
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Have you checked L126, L128, and L145 for continuity?
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  #22  
Old 01-14-2019, 04:00 PM
Jeff Jeff is offline
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Originally Posted by kf4rca View Post
Have you checked L126, L128, and L145 for continuity?
L126, L128, and L145 all measure good continuity, but I do have some news. I've managed to source a working set with an AA chassis, and when I lift pin 12 of the IF amp IC and measure the waveform from pin 12, I get a 4v pp to 6v pp signal, but when I take the very same IC and put it in my set, (I've installed a socket in my set, though the AA's chassis is already socketed) I get a flat line out of pin 12 with it lifted.
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  #23  
Old 01-15-2019, 12:05 PM
kf4rca kf4rca is offline
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That's great

What I would do is put both chassis side by side (make sure everything is connected up) and do comparative ohm-meter checks (with the set off, of course).
I've been thinking you've got an open in the circuit traces some where. Maybe the set took a spill and you've got a hairline crack somewhere.
I've seen that before. Good luck.
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