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I will snap several detailed sections so you can see what's going on here. Give me a few days to get this all together. This morning was our official fishing season opener and a total bust for me. Cool & windy across Knife Lake.
Added some bypass caps to the DC feeds going to the various sections but the shading remains, going to put another day or two into this before I sideline things for a while as I'm getting burned out and need a break. I am starting to wonder if my add-on caps are bad/leaky/high ESR as I'm getting a very well defined 120hz hum, the hum bars are very square and distinct not rounded like a bad capacitor normally shows so later this evening I'm going to cliplead a couple of known good caps in and see where that goes. Never noticed this until the AGC issue was ironed out as it was masking things with its own issues. Set uses a full wave bridge not a doubler and a capacitor input choke so maybe there's some resonance with a failing cap, the original "cans" are out of the circuits and only plugging the holes and I'm using what was supposed to be low impedance Rubycon 450V photoflash caps (EC series) but they're now 20 years old having been installed the summer of 2006. I don't see more than a slight bit of ripple on the post choke side on the scope, manual shows 2V of ripple on the main 410V source to be acceptable so what I have is far below this. A possibility is heater/cathode leakage in V703 which is the AGC/sync sep 6GH8 so I will also sub this with another... I have over 50 new & used pulls to choose from.
On the plus side of all this the IF sections appears to be on the money and the picture is about as good as I remember it minus the 120hz bending. Vertical is running a bit short despite swapping new tubes but overall I'm happy with the progress and may stay with the RF distribution using the CATV head-end Blonder Tongue modulator, its a CAMS-60 MTS modulator with an IF loopthru and I was able to use the IF from this to verify the Magnavox. Not exactly outlined in the service procedures but it works. I feed the modulator directly from a Microtime T100 TBC so everything is about as clean as an actual broadcast.
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