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#2
11-19-2018, 12:31 PM
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#3
11-19-2018, 02:46 PM
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Part Location Diagram
http://i63.tinypic.com/6sun89.jpg Block Diagram http://i66.tinypic.com/sg1vz4.jpg Schematic Diagram http://i65.tinypic.com/10wtld5.jpg Solder Side http://i68.tinypic.com/258nok0.jpg Last edited by Shibby; 11-19-2018 at 02:56 PM.
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#4
11-20-2018, 10:56 AM
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So this is where I get stuck. I tend to be decently good at troubleshooting things as this is what I do every day at work but I am missing the fundamental understanding of how circuits work. Knowing that I am hoping that you guys might be able to steer me in the right direction.
I went ahead and pulled the board last night so I could get a good look at it. After a visual inspection of all of the components nothing seemed too fishy. The smoking resistor I mentioned was indeed burned but seems to have retained its resistance when tested out of series. When in series I get clear continuity between both legs of the resistor. Of course this means that there is continuity between the pads that each leg of the resistor is on. This is where I get lost. If you look at the solder side photo that I attached in my last post and locate Transformer 5004 (T5004) you will see the 2 pads that I am referencing. Unfortunately this service manual does not reference the "burnt" resistor that also shares these pads but if you look at the picture again right where it says T5004 imagine the resistor being right there. On my board it is labeled as R5095. So on my board these 2 pads are shared by 3 components. R5095, C5015, and T5004. After pulling both R5095 and C5015 There was still continuity between the pads. This obviously left me with just the transformer. It is hard to see in the solder side diagram/image but on the laft side of the transformer there are 4 legs. 2 on the upper pad and 2 on the lower pad. You can see the holes for these legs as faint white dots on each pad. On the right side of the transformer are 2 legs thought there are 3 individual pads. Only 2 of the pads are used. According to the parts list this is a "Choke Transformer". After doing a bit of research the configuration seems to match that of a common-mode choke configuration with the left side 4 pins being 2 separate inputs and the right side 2 pins being the output. So I guess here is my question. Should all 4 of the pins on the left side of the transformer have continuity between them? If not I would thing that this is my issue as it is essentially bridging the 2 pads together. If they are supposed to have continuity then what should I be looking at next? I really have no idea if I am even close to barking up the right tree here so please be patient with me. If it helps this is the NEC part number for the transformer with the description. 60906204 COIL,WIDTH CHOKE. That description may be a typo as nothing came up when I googled width choke. Anyways.....Any ides here? I truly am lost. Here is a picture to reference the resistor missing in the service manual Last edited by Shibby; 11-20-2018 at 11:01 AM. Reason: Reference picture added
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#5
11-20-2018, 11:38 AM
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T5004 the side with 4 terminals should have w terminals connected with one trace and two connected with the other. The schematic won't open on my phone so from here I can only make educated guesses. I would assume the resistor is connected across the two traces on the.4 terminal side, and that you are getting a very low resistance across those terminals. A transformer winding is just a coil of wire so assuming those two traces connect to the ends of T5004 there should be a likely low resistance there from the transformer... check the transformers rated resistance on that winding to confirm it is not shorted. Transformers can be wound for any resistance on a winding and anything between .1 and 70k ohm could be possible depending on the circuit.
__________________
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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#6
11-20-2018, 12:21 PM
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I can’t open the schematic either on iPad...also no luck on an Android device... could this be the problem?
Quote:
jr
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#7
11-20-2018, 01:20 PM
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#8
11-20-2018, 01:34 PM
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Ok I went ahead and just created a google drive folder and placed all the pictures i tried sharing before in there. i also went ahead and copied the entire service manual there as well. From here on out anything else I need to add will just get placed in there. I'll also look at putting the link in my avatar for easy reference.
https://drive.google.com/open?id=1lO...R5opTG-QQRkQoo
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#9
11-20-2018, 01:44 PM
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Yeah c5015 is connected across a winding of T5004 and unless the transformer is removed from circuit it's winding resistance will probably dominate any resistance measurements made across the solder pads of c5015...
__________________
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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#10
11-20-2018, 01:52 PM
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__________________
NEC DM-2710: https://drive.google.com/open?id=1lO...R5opTG-QQRkQoo Sony Indextron (KVX-370) Coming Soon! Sony KV-36FV310 Coming Soon!
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#11
11-21-2018, 05:06 PM
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The transformer will be wound with heavy wire & not much so you
will get very low ohms. Unfortunately the ZOOM doesnt blow things up enuf so I can see it. The hoz lin & pincushion usually will be in series with the yoke. Follow the hoz windings of the yoke from the collector of the hoz out transistor through. Watch for a yoke coupling cap in series with it. Also look for any diodes off the C of the hoz output. If any lift one end & do diode test with your meter. Yes I did do some monitors inc NEC. I am NO expert in them. In fact I hated monitors. I was doing piece work for a cat & told him " no more monitors , projos, or VCR / TV combos". All a PIA. Keep in mind monitors were fixed BOARD LEVEL ONLY as far as a MFG goes. Even getting a manual set you back $50 - $75. Add to that you could not buy parts ONLY boards. If you get this going you will have something to be very proud of......... 73 Zeno  LFOD !
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