#1
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Zenith Chromacolor II - chassis 17EC45
Hi all,
I recently picked up this oldie/goodie and I figured I would get some input from the fine folks here. I noticed when I have my NES hooked up the picture is vertically off (I'm at work but I think it was too high up, I'll check again when I get home and update the post). I was wondering if this is a voltage regulation issue, if I need to adjust the deflection yoke, or if there might be a pot I'm not seeing that could do the trick. This guy has a ton of external pots, which is really nice, but nothing like "vertical position" that I see inside or out. I wasn't able to find much info or any schematics. Any info about this set is appreciated! (Sorry for picture quality and dust) Pictures - https://imgur.com/a/DzRQARZ |
#2
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The control would probably be called vert centering...That set may lack such a control...I'd have to dig out the schematic for a look.
You may also be able to improve it with the height/linearity controls...You'll want to have a crosshatch test pattern on the screen or end credits to a movie with evenly spaced text lines...Adjust for minimum vertical overscan AND even spacing of the lines from top to bottom (don't want everyone to become coneheads).
__________________
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 |
#3
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I used to have a set with this chassis, and I loved that set. It had the best picture I had seen on a shadow mask TV. It could look good sitting next to a Trinitron. One thing to look out for on these is the big run capacitor. If it hasn't already been replaced, it will certainly fail in very short order. An A/C supply house will have it. Also sometimes the picture can look a little bit grainy, if it isn't crystal clear, you can tweak the AGC delay and it should clear up. I'm pretty certain this set has vertical height and centering controls.
__________________
"If you wish to make an apple pie from scratch, you must first invent the universe." -Carl Sagan |
#4
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Vert size & centering are on the vert module. Either a
9-92 or newer & better 9-147. You should also be sure the 4-lead cap was updated. Its mounted on the horz output heat sink. If orange its OK. If white it MUST be changed. Early runs did not have one. They use IIRC 5 white caps marked 22-5001. White ones should be changed but its not as critical. 73 Zeno LFOD ! |
#5
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Quote:
__________________
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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That's a nice set, good to know it's in good hands.
No kidding, my 1976 Electrohome used a Zenith-supplied run capacitor which I ended up changing needlessly in an attempt to remedy random brightness fluctuations. I thought it might be going bad because it was getting quite warm, but that will happen to anything mounted on a plate on top of the VRT, doi. I chased that problem around most of the time that set has been in service, finding the cause only a few days ago by accident. It had been holding up well for quite some time, then I tried to get a Sylvania remote tuner to work in there but no dice. I had been using a temporary tuner while the original awaits repairs, it's just sitting in there. Once I reconnected that the brightness started dropping out again. I finally traced the problem to a poorly grounded IF cable; I bent the tabs slightly inward on both ends, shoved the connectors back on and presto, normal brightness. |
#7
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Quote:
I just went down the Automatic Gain Control rabbit hole, I love learning about this stuff but much of it is over my head. Also I'm not sure I would be able to tell if the image is too grainy, most things are pretty grainy over RF. If you have some direction as to where I should look let me know. There are lots of pots and I'm a little nervous to just start poking around. |
#8
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Quote:
Shot of the screen - https://imgur.com/usdLbFP |
#9
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Quote:
__________________
"If you wish to make an apple pie from scratch, you must first invent the universe." -Carl Sagan |
#10
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Looks like you have the early version under run 401.
IIRC one cap behind the h out ( shown), one or 2 on the flyback transformer & 2 or 3 on the bottom chassis. If they are all orange no worries. The white ones open. When they do the HV goes up apx 1.5 KV for each one opened. If it had the 4 lead cap it would be wire tied to the heat sink & is much bigger than the 22-5001. These caps cost Zenith millions. They had to recall about a year of sets. Thats about 20% of 17, 19, 23 & 25 inch sets sold in the US. 73 Zeno LFOD ! |
Audiokarma |
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