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Deader than dead CTC-9
Recently acquired this RCA CTC-9 metal cabinet set, yoke is charcoal along with the horizontal width pot. Knobs are gone and the cabinet has a nice scar on top right corner.
Hope to get it glamed up and working as a daily driver. |
#2
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More pics
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#3
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Great project-some real sharp repairs on that set! Proves that there were always hacks. Lots of fun to bring something like this back from the brink.
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Bryan |
#4
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I have a CTC 11 which was similar. It was great fun solving the problems. The if coils had disintegrated and found exact replacements at a nearby electronics surplus.
Patience and dedication will see you though! |
#5
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If the width pot is the one with the green wire and the brown half a lamp cord wire to chassis, and you judged it with your eyes instead of a multimeter then you may find that it still works...That one seems to use black plastic to hold the resistance material and terminals (instead of the brown phenolic of the other pots) and is likely still just fine.
The yoke is not so much charcoal as disintegrated plastic. The early plastics used for the outer shells on most yokes before the mid 60's were very unstable and will rot away on their own...This even happens to unused mint in box NOS specimens. The windings and important core parts look fine and are probably still safe and functional. The shell can be recreated with a little effort with modern plastics. The part that usually rots away only acts as a mount for terminals as well as a guard to make it difficult for a service tech to accidentally grab those terminals with the set running (it also is supposed to be the grab handle to adjust the yoke). You want to avoid touching the yoke terminals if the set is powered on...The meanest shock I've ever gotten from a TV set was a CTC-15 clone that I touched a portion of the yoke winding where the insulation was bad...That is the only time I can remember my 'let go of this' reflex kicking in full strength...
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Tom C. Zenith: The quality stays in EVEN after the name falls off! What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4 |
Audiokarma |
#6
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Quote:
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#7
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I am fairly certain that yoke is cactus. A ring test should prove it. I've seen yokes looking like that before and they were all crook with shorted turns.
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#8
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Working on one right now. Bad Bubblebees in the horizontal circuit. Nasty things that they are.
Dump the Black Beauties as well, and of course paper. The set is like new now. Not to rub it in, just to say I feel your pain. Pix to follow... Last edited by Sparky; 09-14-2018 at 02:03 PM. |
#9
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The 106305 Deflection Yoke is a Y-107 according to my 1983 Thordarson TVPG-15 book. The Sams 459, page 11, doesn't cross it.
Check the horizontal centering pot on the flyback and the brown dipped caps in the vicinity, as well as the 56pF 6KV disc. Mine were all off and leaking. The current went way down after replacement. Last edited by Sparky; 09-28-2018 at 12:35 PM. |
#10
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Quote:
I had to replace the horizontal width pot as the fine wire was all tangled up inside and believe it shorted out taking the resistor on the back of it and the horizontal winding on the original yoke with it. I also replaced the two caps in that area. I now have HV but it needs to be reduced. |
Audiokarma |
#11
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Progress so far;
HV is 29+KV and turning up the horizontal makes it go higher. Chassis is back out for resistor checks and cap replacing Starting with the horizontal board and vertical board |
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Yep, looks like you're on track (sorry, couldn't resist!) Here most folks have trouble with HV being too low...
__________________
Bryan |
#13
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May want to get the HV reg working first. If you run it that high too long you may damage the CRT and or flyback with internal arcing.
__________________
Tom C. Zenith: The quality stays in EVEN after the name falls off! What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4 |
#14
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Wow that seems like run away hv,+29 kv if the fly can put that out it should last a while provided it is lowered.
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#15
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Timmy, when you adjust the HV down to 25K, you will actually be putting more load on the flyback. Remember, the total load on the flyback is the sum of the current drawn by the CRT and the current drawn my the HV voltage regulator. As the scene on the CRT gets brighter, the CRT draws more current while the voltage regulator draws less and vice versa. The whole idea of shunt regulators is to present a constant current load to the flyback/HV rectifier under all screen brightness levels.
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Audiokarma |
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