nashou
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Post by nashou on Mar 16, 2017 21:34:32 GMT -5
yep, so far so good I think.
I'll replace those optocouplers with the new ones along with ic901. then we'll cross our fingers.
nashou
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Post by mastertech on Mar 16, 2017 21:37:07 GMT -5
Did you test those parts I posted a few post back in that small square?
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nashou
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Post by nashou on Mar 17, 2017 14:11:55 GMT -5
Did you test those parts I posted a few post back in that small square? Q919 and Q920 I checked when I checked ic902, the mosfet that was bad, they were good. Aslo i checked all diodes at that time and the two regular diodes I had to lift one leg to be able to read them normal. The Zeners I checked again last night on board and they were fine . Maybe I should remove the SMD zeners and check them out of circuit? Nashou |
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Post by mastertech on Mar 17, 2017 20:13:49 GMT -5
If they are not showing short in both directions then I would not bother pulling them.
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nashou
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Post by nashou on Mar 18, 2017 19:00:13 GMT -5
well parts cam in replaced all optocouplers and ic901 and no change.
So i began looking at the parts in the little square you marked .
Pulled Q920 and 919 and the zeners and they read fine.
5 volt is there on the connector when jumped .
No other voltages are there the 12 or the 24 .
crap !!!
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Post by mastertech on Mar 18, 2017 19:02:18 GMT -5
How about the 5v on the vcc's?
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nashou
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Post by nashou on Mar 19, 2017 5:26:20 GMT -5
Didn't check those.
I will later .
Nashou
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nashou
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Post by nashou on Mar 19, 2017 16:16:19 GMT -5
ic 902 5.05
ic901 4.49
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Post by mastertech on Mar 19, 2017 16:40:44 GMT -5
When you get time get me these voltages with all parts in and normal and standby jumped to 5v.
ic902: Pins-
1___
2___
4___
5___
7___
ic901: pins-
1___
2___
3___
4___
5___
6___
7___
11___
14___
15___
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nashou
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Post by nashou on Mar 20, 2017 19:31:56 GMT -5
When you get time get me these voltages with all parts in and normal and standby jumped to 5v. ic902: Pins- 1___1.02 2___0 4___.3mV 5___.9mV 7___0 ic901: pins- 1___7.6mV 2___1.6mV 3___.2mV 4___181.mV 5___323.mV 6___0 7___.830vdc 11___15mV 14___20mV drops slowly 15___20mV drops slowly Pin 16 had 1.667 |
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Post by mastertech on Mar 20, 2017 19:38:26 GMT -5
Did you use hot gnd?
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nashou
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Post by nashou on Mar 20, 2017 19:58:56 GMT -5
Yes, I found another bad part I think. Q915, i found it had a reading between the two pins on the same side and the lone pin. where as Q917 read an OL on one of the two pins. This is in diode mode. So I removed it and tested in my tester and it reads as damaged. I got to looking at from the Optocouplers voltages in pins 3 and 4 . one of the pins on two of them had a small voltage less than a volt, but ic909 had none at all so I searched around there . |
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Post by mastertech on Mar 20, 2017 20:09:10 GMT -5
That is odd since we had already verified that circuit as working because Q915 has to work to turn on the vcc to the 2 ic's.
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nashou
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Post by nashou on Mar 20, 2017 20:27:31 GMT -5
That is odd since we had already verified that circuit as working because Q915 has to work to turn on the vcc to the 2 ic's. How would I check it with my DMM instead of the testers I used, both read damaged part. Should I swap Q915 the one I removed with Q 917 and see what happens? I'll double check. some times the legs of the chip don't make contact with the testing pads. but I bent them down so they would make contact. Nashou |
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Post by mastertech on Mar 20, 2017 20:32:14 GMT -5
With DMM on diode mode and 1 probe on base and the other probe on emitter or collector it should read flow in 1 direction and none in the other. With either probe on collector and emitter there should be no flow in either direction.
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