#16
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The resistors looked "different". IIRC they turned color & got a bubbly
coating on them. Lift one end & retest them. Same with transistors not in sockets. Lift 2 out of 3 leads & test with DVM on diode test. We had a few transistor checkers & they collected dust. Only one tech used them & he was playing engineer & wasting time. Bottom line is parts IN circuit very often read bad. 73 Zeno LFOD ! |
#17
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Unfortunately no, but 98% chance I have the schematic. I'm hoping to have bench time this weekend, maybe I can dig it up while I'm down there.
__________________
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 |
#18
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I saw that my Sylvania TV is in Sam's 1045-2 which I don't have a physical copy of and I try to avoid buying the PDF copies from them unless I have no choice in the matter because I think its ridiculous to charge $22 for a PDF reproduction of an original service manual that may or may not be of that great of quality compared to the original paper document, and feebay is hit or miss on having original Sam's Photofacts for sale, and some times they want just as much on feebay for an original Paper copy as Sam's does for a PDF reproduction. Which is why if someone on here has an original paper copy that they can scan and upload I prefer to go that route rather than having to pay $22 for a photocopy of an original Sam's, or if I can hold out for someone locally that might have a bunch of old sam's folders that they are liquidating from their collection for a decent price, like what Shango did.
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#19
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Well, I did suprisingly enough manage to find an original hard copy of Sam's folder #1045 (the whole folder, not just one of the sections out of the folder) for $9 plus shipping.
But I had to search a little bit because there weren't many listings for individual Sam's folders, they were mostly just listing the compilation books or selling a set of Photofact Folders as a lot (with one such listing being listed for $800 for a set of 50 complete Photofact folders that were in no particular order) with only 2 listings that were selling individual folders out of a lot of 50 or 100 Sam's Folders, that I'm assuming came from an old repair shop or an old Library collection. The one listing that was selling individual folders out of a full lot of Sam's folders had Folder 1045 but it was already sold, and the second listing had 2 Sam's 1045 folders and one had already sold and I had just bought the last one out of that lot. So it seems that these Sam's folders are getting harder to come by unfortunately. |
#20
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Quote:
It must be a curbside pickup, that someone tried to get to the yoke! |
Audiokarma |
#21
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I don't know how the back cover got broken, I just know that the person I got it from on facebook market place said that her husband picked it up from a garage sale 10+ years ago and intended to fix it up but had some health problems that got in the way of that endevor.
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#22
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Quote:
According to the resistor color coding on the 2 2W carbon comp resistors you're referring to are supposed to be 68k Ohm resistors and then there are 3 green wirewound resistors on the same board that are 27k Ohm 3W power resistors which all measure within spec yet, but the 2 2W Carbon Comp Resistors which are supposed to be 68k Ohms are measuring only 16k Ohms or so, so it sounds like those carbon comp resistors need to go bye-bye, because they are WAAAAAYYYY out of tolerance. Probably what I'll do to replace those 2W 68k Ohm resistors is cut them off on either side of the resistor element casing and then solder a new one onto what's left of the wire connectors above the board so that way I don't have to worry about risking damaging the circuit traces underneath the board, since they left about a 1/4" of wire lead above the board surface. |
#23
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IMHO you'd be better off waitin for a Sams to double-verify those resistors' value. Code stripes can change color from excessive heat over long duration. Gotta wonder if the two transistors might still be good though.
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#24
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When I get that folder I'll take a look at the manual for the TV and double check the resistor values. |
#25
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I got the manual for my TV in the mail today and I just confirmed that the 2 2W Carbon Comp resistors in the TV were indeed 68k Ohm 2 watt resistors and what I was measuring on them using my VTVM was about 16k Ohms which is indeed way low.
And I believe that VTVMs can be used to measure resistors in circuit regardless of there being a parallel load on them or not because the VTVM applies a voltage to the resistor when measuring it that makes it read like the resistor is out of circuit, at least that's my understanding of how VTVMs work, compared to DMMs. |
Audiokarma |
#26
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#27
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Anyways regardless the resistors should be easy to clip out of circuit because they do stick up above the board about a 1/4" so which means that if those resistors are actually fine then I can just solder the resistors back onto the leads that were clipped. Last edited by vortalexfan; 07-27-2023 at 10:02 AM. |
#28
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Quote:
One while you can measure resistors in circuit with any resistance meter the reading in circuit is never guaranteed to be the actual resistance of the resistor due to parallel paths. No meter can eliminate parallel paths...If it claims to, it's lying. When measuring resistor in circuit if the value is exactly as rated or higher it's probably accurate, if it's lower you have to unhook one lead. Two it's really better to pull the chassis and solder on the board than clip and tack it back together, both from a neatness standpoint and from a on thicker leads to get a good joint you can end up melting the old board joint causing the lead to fall through the board or a cold solder joint on the board to develop standpoint.
__________________
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 |
#29
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Quote:
I was reading/following another member's thread where he was repairing a Color TV of a similar vintage to mine (the one where he was working on a late 1960s Motorola Color TV that had issues with the color not wanting to lock in correctly) and there were some suggestions about using some 2%-5% tolerance resistors in the IF and Chroma sections of the TV to get it to work better. I wonder if in my TVs case that might be something worth looking into to get the TV functionality more stable, because my TV is essentially exibiting those same issues as that Motorola TV in the aforementioned thread, where the picture and color are not stable. |
#30
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UPDATE: I was able to locate my DMM and I was able to confirm tha those resistors were indeed around 75K ohms so like I said I'm guessing that is way above the 10% tolerance the resistors are rated for so I'll need to replace those for sure.
So according to my calculations the resistors are just barely outside of the 10% tolerance range, 74,800 Ohms and under is within the 10% tolerance range of the 68K Ohm resistors and the resistors were measuring 75,300 Ohms... Which is probably the reason why those resistors haven't cooked themselves yet and also probably the reason why the transistors may not of fried yet, but are still affecting the picture quality, but also I haven't ran the TV for more than a few minutes at a time to do some troubleshooting and shutting it off in between. Last edited by vortalexfan; 07-27-2023 at 02:27 PM. |
Audiokarma |
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