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#31
11-10-2014, 11:08 AM
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A quick check on your video drive problem: check the video output tube then the electrolytic cap in the cathode circuit of that tube. your CRT may be good, but a low drive signal to the cathodes can make it look sick.
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"When resistors increase in value, they're worthless" -Dave G 
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#32
11-10-2014, 10:24 PM
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Quick update
tonight I worked through the dynamic and static convergence and i was able to get it pretty good exvept for the upper left center. I also got the purity better. The picture still has way too much contrast and not enough brightness, but I got the gray scale pretty much spot on too. After looking at the chassis closely I think I will be able to get at most of the caps so I might replace a few and spot check a couple resistors. I also wanna take a look at the filter caps at the front of the chassis and clean the tuner just for posterity...
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Lebe dein leben für dich selbst **Searching for any all tube or hybrid or color portable sets would consider some early solid state color too** Last edited by josephdaniel; 11-10-2014 at 10:30 PM.
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#33
11-10-2014, 10:30 PM
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Ya know, the picture really is worlds better now from when it was when i first received it...
Tommrow I will take a look at this sub-brightness control I just found. I will also see about replacing a couple tubes that have a high failure rate and ones that are suspected of being bad...
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Lebe dein leben für dich selbst **Searching for any all tube or hybrid or color portable sets would consider some early solid state color too**
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#34
11-11-2014, 11:47 AM
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When I pull the chassis should I bother replacing any of those maroon drops? I am gonna try and get at most of the electrolytics but I am not certan about them... I am really leaning towards just replacing them while I am in there since I would really like this set to work for a long time...
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Lebe dein leben für dich selbst **Searching for any all tube or hybrid or color portable sets would consider some early solid state color too**
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#35
11-11-2014, 05:51 PM
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In my opinion, if you want this set to last a long time, and remain functional, you should
not replace any capacitors unless you have tracked down a problem directly to one. I went through a number of parts changes on this set in an attempt to get a better picture, I also changed video amplifier transistors, caps, and a few in the color circuits.... Parts that with tv repair knowledge I thought might be effecting picture quality, I did not get any improvement, my tv looked just like yours does.... It's kinda like some portacolor sets, there just gunna get so good and that's it.... It is kinda a shame, they did a really nice job designing it, it's well laid out, nice circuitry, etc. Maybe it needs more of a going through on the video amplifier circuits than I did, but I would hate to see you waste a lot of time, money, and possibly even install lower quality replacement parts than are in it now, and get a less reliable, and possibly poorer performing tv than you have now.... The best thing you could do in the way of improving picture quality would be to test the video amplifier for it's frequency response using equipment you most likely do not own... I have wondered if the video amp circuit had poor response, or if its some place else.... .
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Yes you can call me "Squirrel boy"
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#36
11-11-2014, 06:51 PM
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Ya probably don't have an old school eye type cap checker. If you did I'd say to test all the maroon drops and lytics in the video stages. Maroon drops virtually never short (the failure mode that makes more things fail), but older drops have been known to go openish or to drift in capacitance value to the point of making circuit performance rather poor to outright bad. Sets that have PCBs I have no issues with replacing the drops in any stages that seem deficient in performance. On a CTC-15 clone set replacing the drops on the video/color board yielded a rather noticeable improvement in performance (it made me wish I'd done so earlier).
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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
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#37
11-11-2014, 07:28 PM
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All right, so I guess I will not replace those film caps, but I am going to replace the axial electrolytic caps that are in there. When I say relaibale I mean that in another 30 years if I just plugged it in it would work with out much fuss.... I know that is highly unlikely, but I highly doubt those old electrolytic caps in the set will be very good in 2045 :p those electrolytic caps in this set would be 76 years old by then! I do know how to solder, and I am much more conformable on PC boards than I am with point to point wiring since I have quite a bit more experience with it...
The set does have very good picture now, but there is just not enough brightness... I will probably get around to looking at it later this weekend...
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Lebe dein leben für dich selbst **Searching for any all tube or hybrid or color portable sets would consider some early solid state color too** Last edited by josephdaniel; 11-11-2014 at 07:37 PM.
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#38
11-12-2014, 04:19 PM
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Brightness issues should always start with voltage checks of the pins on the CRT (assuming its good of course). the bias of the CRT (K to G1) the screen grids (G2) and the HV pretty much dictate the brightness. oh and it would not hurt to confirm the filament voltage as well.
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#40
11-25-2014, 10:30 PM
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Just a small minor update, I have the set going pretty good and reliably now. I did the convergence a while ago, but it looks like the red has drifted a bit so I will redo that and then button the set back up and leave it how it is. If I can ever remember, I will upload a copy of the sams...
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Lebe dein leben für dich selbst **Searching for any all tube or hybrid or color portable sets would consider some early solid state color too**
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#41
02-01-2015, 10:01 PM
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I have a set very close in relation to this one. I haven't powered it on in several years, but I recall it worked alright last time I messed with it. I vividly remember using it during the analog broadcast days. It used to get a very strong and clear signal from WISN 12 in Milwaukee just off the internal rabbit ears.
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