nashou
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Post by nashou on Mar 15, 2017 16:25:05 GMT -5
That seems a little to low. What do you have on ZD913? 2.17 cathode 1.36 Anode noticed on all connector pins I have 70 vdc on the 5v ,24v, gnd, 12v and the power on/off pin has 63vdc |
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Post by mastertech on Mar 15, 2017 16:30:57 GMT -5
That is probably because you are using hot gnd when testing them. Those need to be tested using cold gnd.
Your cathode voltage is to low. You need to value test R974,R975,R977, and diode test ZD913.
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nashou
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Post by nashou on Mar 15, 2017 16:44:39 GMT -5
Ok weird, with neg prob on r974 the side that goes to Anode of Z913 I get 3.93M for all resistors .
But if I switch the leads I get 1.54M .
Also for the ZD913 I get OL one direction .674 the other , while all other zeners have some reading in either direction.
Might be bad. That is a 9.1v right? I have some in stock.
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Post by mastertech on Mar 15, 2017 16:59:21 GMT -5
You may have to lift a leg or remove those resistors to test accurately.
That ZD reading looks ok.
Diode Test ZD910,ZD911,ZD912,D924,D908.
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nashou
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Post by nashou on Mar 15, 2017 17:23:33 GMT -5
You may have to lift a leg or remove those resistors to test accurately. That ZD reading looks ok. Diode Test ZD910,ZD911,ZD912,D924,D908. ZD910 +A .635 -A .814 ZD911 +A .450 -A .OL ZD912 +A .644 -A .990 D908 +A ..466 -A .963 Bad? D924 +A .450 -A .OL good Resistors read ok out of circuit the "A" is the anode and then the polarity of the probe is the + or - |
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Post by mastertech on Mar 15, 2017 17:44:47 GMT -5
ZD910,ZD912,D908 are all questionable. Need to be checked out of circuit.
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nashou
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Post by nashou on Mar 15, 2017 17:44:47 GMT -5
Pulled D908 and it measure good
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Post by mastertech on Mar 15, 2017 17:45:48 GMT -5
Also check D903.
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nashou
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Post by nashou on Mar 15, 2017 18:05:11 GMT -5
Took all out except D903 and all measured ok , the zeners I tested using my DC power supply and they hold the values they should have.
D903 measured fin in circuit .393 one direction OL the other.
I'm getting no voltage on D927 on any pins but the dual diode reads fine. Can the transformer go bad? How do I test T904 or am I going in the wrong direction?
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Post by mastertech on Mar 15, 2017 18:14:23 GMT -5
You are jumping to far ahead with D927.
I need you to put all parts back in and get me a DC voltage reading on both sides of D903. Hot gnd.
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nashou
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Post by nashou on Mar 15, 2017 18:17:41 GMT -5
164 Cathode side
164 Anode side as well ?
Hmmm
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nashou
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Post by nashou on Mar 15, 2017 18:39:09 GMT -5
Stepping out for a bit.
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Post by mastertech on Mar 15, 2017 18:52:54 GMT -5
Ok. when you are back get me DC voltage on both sides of ZD911 and D924. Again, be careful of shock. This is DC voltage with hot gnd. It is not on safety gnd.
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nashou
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Post by nashou on Mar 15, 2017 19:00:04 GMT -5
Ok. when you are back get me DC voltage on both sides of ZD911 and D924. Again, be careful of shock. This is DC voltage with hot gnd. It is not on safety gnd. Ok, yeah I use grabbers then plug in board each time. I am testing the board out of the TV on my bench. It doesn't need to be in TV right? nashou |
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Post by mastertech on Mar 15, 2017 19:02:29 GMT -5
Correct.
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