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#16
12-20-2014, 12:52 PM
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#17
12-20-2014, 03:41 PM
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I've said it before, and I'll say it again: I never take the sam's diagram's version of how a set ought to be wired over the actual wiring in the set!...Unless I see evidence that that a hack repairman has been in the section I'm working on or the the section where I see a difference does not work properly after all caps have been replaced and all other parts in the circuit have been confirmed to be good.
Sam's has had SO MANY typos/errors over the years (not to mention they often missed documenting production changes)that I consider taking their folders as the bible on any given set to be almost the same as asking to be instructed to sabotage your own set! I've screwed up good circuits in sets, and caused myself many headaches by blindly assuming that the sam's was infalible.
__________________
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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#18
12-20-2014, 06:21 PM
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may want to change it. It cant be a 680 ohm as the Sams says. If it were the 250V would be go to ground through the 680 ohm & R67 a 1K. That would make lots of smoke  Also C2 is probably rated at 50V, KABOOM  BTW if C2 opens the bottom of the pix will pull up, common. Bottom line is Sams has at least 2 errors. But I will not beat up on them. Imagine the hobby or the former industry without them. And factory manuals are not without sin either. That may make a good new thread someday  Good luck with the Zenith. 73 Zeno 
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#19
12-20-2014, 09:26 PM
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Sams are a snapshot of two TVs in the total production - and not wholly representative of the entire production of that model/chassis. There is a really good article in PF reporter about the troubles that Production Changes bring, and the necessity that manufacturers report them to Sams, thus giving the whole picture. RCA, Westinghouse, Magnavox, GE and Philco were lauded in the article for providing the changes. Zenith, Sylvania, Admiral and Sears weren't so generous, which is why all of the Sams for those sets are to be suspect should the circuitry differ. Note that the Sams website DOES NOT report Production Change Bulletins like the printed indexes did. That is why the paper indexes are so valuable, and much needed, especially for the older sets. The PCBs are in the index as parenthesis-items, and are noted as such: CTC38 1000-1 (PCB 1231-9) If you have a later chassis, that PCB could save your head from spinning. I got bit back in the early 80's when working on an old Teledyne/Packard Bell Solid state set. Sams didn't show any changes, yet the vertical had changed....dramatically, with the addition of a few diodes and resistors in the blanking and yoke return. One call to Teledyne, and I got what was needed - a change, issued some 9 months after the date of the Sams. Apparently Teledyne had three production runs of the same chassis, and never reported it to Sams. Easy way to make some money for themselves, selling updated manuals. Same for Zenith - anyone familiar with their CM manuals and the updates, where you replace an entire manual with another. It was tempting to "save" the outdated manual, and keep it for further use, despite it having errors and omissions. RCA was the same - the CTC16 data I have is the "FIFTH printing", and I also have the 2nd and 4th, which are both very different parts-wise. So I guess I can say while Sams does have errors, not all omissions or changes are errors on Sams' part.
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Brian USN RET 22YRS (Avionics/Cal) CET-Consumer Repair and Avionics ('88) "Capacitor Cosmetologist since '79" When fuses go to work, they quit!
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#20
12-21-2014, 12:46 AM
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The errors I was referring to are TRUE ERRORS such as the schematic and parts list in one folder showing a factor of 10 difference on a capacitor value, and another where the tuning cans for different remote functions were interchanged on the chassis layout.
I can tell the difference between a production change and an error just fine. An error is the above, similar things and sometimes a part having the wrong value listed (although that can fall under production change some of the time). A production change is when the schematic has a different number and or configuration of parts than the set and possibly value changes of parts have been made. I'm a Zenith man so I don't work on much PCB based stuff...The only pure RCA product I've worked on is a CTC-4, unless you count CTC-15 clones.
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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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#21
12-21-2014, 01:29 PM
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I think we are saying the same thing - errors exist in SAMs. As for PCBs, some PCBs REMOVE parts, leading to the conclusion the SAMs is wrong. I helped a fellow VKer with his RCA, which had a PCB that removed several parts-didn't change them, just removed them:http://www.videokarma.org/showpost.p...97&postcount=8
My point is merely that with SAMs, you really can't tell. If the schematic or parts lists differ, you can't rule out a PCB if you don't have that PCB. SAMs website won't help, as they don't mention them, only the paper indexes do. Awhile back I was working a Zenith 19EC45 set. SAMs doesn't show changes to the power supply, the Zenith data does, and the TEKFAX is different that Sams and the Zenith data. The PCB listed by SAMs doesn't affect the power supply circuitry that is different. Conclusion is that SAMs didn't get the PCB from Zenith, as Zenith data clearly lists the correct info. So while SAMs does have errors, not all differences or omissions are errors on SAMs' part.
__________________
Brian USN RET 22YRS (Avionics/Cal) CET-Consumer Repair and Avionics ('88) "Capacitor Cosmetologist since '79" When fuses go to work, they quit!
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#22
12-22-2014, 01:22 PM
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Quote:
__________________
Brian USN RET 22YRS (Avionics/Cal) CET-Consumer Repair and Avionics ('88) "Capacitor Cosmetologist since '79" When fuses go to work, they quit! Last edited by Findm-Keepm; 09-29-2017 at 06:38 PM.
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#23
12-22-2014, 01:58 PM
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Before you remove the part;
Does the part look age appropriate with the other parts already in the set....? Do the solder joints look undisturbed...? Was it original looking in its installation...? If it perhaps looks newer, or if the solder joints look recently disturbed.... Then is there a possible nearby location where this part may go....? As in, did someone accidentally put this part back in the wrong spot making a previous repair....? If it's connected off the cathode of the vert output, 100uf cap, (it's the only 100uf cap I see in the schematic clip posted above) Then, the set had a minor linearity issue, or a sync issue and someone fudged the circuit.... I can't see it making a really big difference given the values of the other resistors to ground in that area... Remember ground and voltage sources are both looked at as a sink as far as signal goes..... If it's a voltage source than what, the screen on the sync tube must have been floating too low..... Fix the set, then run it without it, and then put it back and see what it does.... At that value it ain't gunna make that big a difference... See what happens.... The guy that put it in was either a schmuck, or a genius! .
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Yes you can call me "Squirrel boy" Last edited by Username1; 12-22-2014 at 02:30 PM.
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#24
12-22-2014, 11:44 PM
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I saw your request over on ARF-the Zenith schematic is in both the 1954 Beitmans Tv-7 and Radio Electronics Magazine:
http://www.americanradiohistory.com/...-Page-0084.pdf http://www.americanradiohistory.com/...-Page-0085.pdf Hope this helps.
__________________
Brian USN RET 22YRS (Avionics/Cal) CET-Consumer Repair and Avionics ('88) "Capacitor Cosmetologist since '79" When fuses go to work, they quit!
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#25
01-12-2015, 10:36 PM
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After doing a power on after replacing all caps and some resistors I was able to get a picture.
I had some issues with horizontal and vertical hold so I went back and replaced more resistors that tested ok when I check the set originally. It still has horizontal hold issue. I uploaded a youtube video. Is there anything I should look into? http://youtu.be/RoxY6O8WNYk
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#26
01-13-2015, 08:24 AM
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You're right, S.C made the phones better than the Tvs..
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#27
01-13-2015, 09:11 AM
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parts between the sync sep & horz osc tubes. 73 Zeno
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#28
01-15-2015, 11:41 PM
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After doing some more work on the set I found some micamold/mica caps and I am wondering if they are paper and if they could be causing the issue. A troubleshooting book suggested the picture vibration might also be caused by IF tubes.
What do you guys think?
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#29
01-16-2015, 01:32 AM
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To footlooseman: An IF tube will not cause weak H sync like shown in the vid. Last edited by old_coot88; 01-16-2015 at 01:35 AM.
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#30
01-21-2015, 02:28 PM
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I showed my co-worker the video with the horizontal. He used to be a TV repair person back in the 80s and 90s and thought the horizontal issue could be caused by the flyback transformer. There were some cracks and if I recall correctly missing insulation (I have to take photos tonight). Do you think I should look into buying a replacement?
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