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#1
01-23-2010, 07:16 PM
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RCA KCS-47A Riddle
What works fine then goes Zorch!!! and smells like burning rubber? My faithful 6T71 was working fine last night till it made a buzzing sound and the screen went dark. It also emitted an odor of burning rubber. Sound went dead but came back after a few seconds
About three years ago I when though it and replaced a bunch of resistors, all paper & electrolytic caps, + some bad micas. Set has been working just about every day since. I got a chance to pull the chaiss out tonight. I was expecting to find something all burned up but I'm not seeing anything that looks bad. I remember Bill C mentioning something about the damper tube filament/cathode shorting and taking out the power transformer. HV fuse is good, maybe overrated as I don't think I could find that low current one when I was working on the set years ago. Flyback resistance is about right as per the Sam's. Haven't had a chance to hook up the jumpers so I can fire it up outside of the cabinet. Any thoughts? Terry Last edited by 7"estatdef; 01-23-2010 at 09:07 PM. 
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#2
01-24-2010, 03:25 PM
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Found the answer to the riddle. Filament winding for the 6W4 was arcing at chaiss under the TV/Phono switch. Will repair by adding a 6v3A transformer. Hope it didn't damage anything else.
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#4
01-25-2010, 07:09 AM
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Oh that's just the one that shocks you when you touch the chaiss and ground.
Terry
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#5
01-25-2010, 10:38 AM
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Quote:
Get that thing outta' there!! 
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#6
02-01-2010, 09:15 PM
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Well I disconnected the original filament wiring and hooked up a separate filament transformer for the damper tube. Also replaced the lead on the flyback to the 6BG6 plate cap. Put it all back together and it worker great!!The best picture I've seen on that set. For a hour. Came in here to the computer for a bit and smelled something bad in the other room. I think the replacement transformer didn't have enough insulation and it arced over internally.I could hear it arcing. I not quite sure what happen after that but it toasted the width coil, that's what was stinking up the joint. Lost hv to the crt.
Dug up a transformer with a 3Kv insulation and install that. Replaced the width coil. Wasn't making enough hv and had shrunken picture. Long story short replaced the 6BG6 & 6W4 and it seems to be working great again. I think my wife thinks it's going to set the house on fire! Terry ps Anybody got a spare width coil for a RCA KCS-47A?
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#7
02-03-2010, 10:06 PM
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Have you located a coil? I researched it tonight-they don't actually use a width coil, but do list a linearity coil which is RCA #71449, Merit #MWC-12, Stancor WC-5, Thordarson WC-14, Triad WLC-3. None of them in my stash, though
__________________
Bryan
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#8
02-04-2010, 05:39 AM
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Hi Bryan
Actually on the diagram it called the width coil on the chaiss it marked horizontal linearity. Haven't dug up yet. Seems like there's a lot of old RCA's out there. Terry
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#9
02-04-2010, 06:42 PM
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I have a question, Where does the 6W4 cathode/filament find ground? From the diagram looks like the plate, cathode, and filament are isolated from ground and all of the connection are at a high potential.
Tnx Terry
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