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Post by mastertech on Mar 16, 2017 19:29:12 GMT -5
Test for it across C934.
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nashou
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Post by nashou on Mar 16, 2017 19:38:02 GMT -5
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Post by mastertech on Mar 16, 2017 19:42:18 GMT -5
Remove the jump at ic911 and recheck at both places.
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nashou
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Post by nashou on Mar 16, 2017 19:47:08 GMT -5
Ok, it fluctuates unstable . From 7.8 to 9.4 then cycles again .
Nashou
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Post by mastertech on Mar 16, 2017 19:50:22 GMT -5
I would like to test it with that optocoupler in place. If you have the time I can explain how to test an optocoupler and you can then put 1 in that place and test. Let me know if you have the time.
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nashou
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Post by nashou on Mar 16, 2017 19:52:03 GMT -5
In between your responses I found a way to test the optocouplers . I took a 330 ohm resistor and connected it to pin 1 then connected the positive DC power supply to the end of the 330 ohm, and the neg clip To pin 2 . Then the ohm meter to the collector and emitter of the chip, pins 3 and 4 . Then you increase the voltage and as it increases the ohm's reduce and as you reduce The voltage the ohm's should increase. One behaved nice and smooth. The other two at a certain point went to OL then began to read again. I need to order those as well. Nashou you must have missed this post  Unless you have another way? |
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Post by mastertech on Mar 16, 2017 19:55:43 GMT -5
No, I did not miss it but it is close but not quite correct. With your DMM connected to pins 1 and 2 and set to continuity it should read open. Then your external supply set at 5v and pos on pin 1 and neg on pin 2 and when powered your DMM should read continuity.
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nashou
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Post by nashou on Mar 16, 2017 19:57:08 GMT -5
No, I did not miss it but it is close but not quite correct. With your DMM connected to pins 1 and 2 and set to continuity it should read open. Then your external supply set at 5v and pos on pin 1 and neg on pin 2 and when powered your DMM should read continuity. Aha Another way !!!! I found the way i did it here www.electronicrepairguide.com/optoisolator-ic.html |
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Post by mastertech on Mar 16, 2017 20:06:56 GMT -5
Then find the one that seems to work the best and put it in ic911 location and test your 5v at the connector again.
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nashou
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Post by nashou on Mar 16, 2017 20:14:28 GMT -5
Ok, it read OL on all three. and the current meter was the only thing that moved and the voltage on my DC supply dropped .
could they all be bad?
Unless i need to change the polarity on the pins from the PS?
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Post by mastertech on Mar 16, 2017 20:20:12 GMT -5
Power should be on anode, (pin 1).
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nashou
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Post by nashou on Mar 16, 2017 20:22:57 GMT -5
Power should be on anode, (pin 1). yep, no continuity with power on. The Meter jumps up and voltage meter drops . On my tester the diode side reads ok . i cant not test the other pins ( 3 and 4)as there is no base pin |
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Post by mastertech on Mar 16, 2017 20:27:32 GMT -5
Put 1 in ic911 and see what the 5v tests at.
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nashou
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Post by nashou on Mar 16, 2017 20:41:34 GMT -5
Put 1 in ic911 and see what the 5v tests at. 4.45 vdc |
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Post by mastertech on Mar 16, 2017 20:43:04 GMT -5
good. Now jump the 5v to standby at cn902 and recheck the 5v at the same connector (cn902).
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