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Post by justgreg on Feb 28, 2015 19:52:01 GMT -5
.979 = Red on pin 1 .491 = Red on pin 2
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Post by justgreg on Feb 28, 2015 15:25:05 GMT -5
What are your thoughts on: *Temporaryily bridging/replacing the lifted diode with a resistor (suggestion for the value?) *Applying 1.5vdc input at the mains in *Using freeze spray to identify hot components
The lowest voltage TP I found was 1.8v. The variable voltage wall wart I have (RatShack) only goes as low as 1.5v but I can add a resistor in-line. (suggestions for a value?)
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Post by justgreg on Feb 28, 2015 14:29:19 GMT -5
Just re-reading. Yes I meant diode scale. Here's the backside under the diode showing the 4 holes. Camera will take good macros one time and be crap the next. I hope this is the detail you wanted.
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Post by justgreg on Feb 27, 2015 23:32:24 GMT -5
Yup...understood about testing caps in situ. I have a Blue ESR but I was just killing some time testing across caps. Before you posted I had time to think about what I was doing. It was a flawed assumption on my part thinking that I could point my finger at a cap that tested shorted across because it dawned on me that we're trying to find a short on the power rail, so of course a cap could show a short on both sides when tested in-circuit. Live and learn. I'll post a pic of the backside of the area you marked and post it tomorrow. Damn flu has me whooped. Thanks again for your help so far Mac!
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Post by justgreg on Feb 27, 2015 22:28:06 GMT -5
hahahahaha Sorry about that. When one doesn't know the language you either talk loud...or make up words.
I assume you understood the first part? With one end of the diode lifted I still get a short at the pad it was formerly soldered to Conversely when I tested from the raised end of the diode I got a reading of around .965 on cap scale.
The next part was a question about SMD caps. Should I ever get a continuity tone when testing across a cap? With an electrolytic it indicates an internal short. With a ceramic SMD I don't know if I can get a continuity tone by design of the cap, or if it indicates the cap is internally shorted like a bad electrolytic.
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Post by justgreg on Feb 27, 2015 21:38:32 GMT -5
Well shucks. I lifted the opposite end that's furthest from the mains...still a short. Dang it. I the power switch and it's functioning correctly so no easy fix there. Question on SMD caps. I expect to get a tone from SMD filters (L) but should I get a tone from SMD caps? I started the pain staking job of checking all the SMD caps and found one (so far) that produces a tone across it's poles. And...when you test a couple hundred of the little buggers how do you keep track of the ones you've done? Wish I had a fine point white paint pen.
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Post by justgreg on Feb 27, 2015 21:00:38 GMT -5
Well I appreciate you sharing it just as much as the rest of the world must be. lol
I did some research on the diode yesterday and it came back as a zener diode. The pix I took are better than my eyeballs (until my just ordered digital magnifying cam comes in!). I zoomed in on pic 3 (the best quality) and the only markings I can see is a blue band and a black thinner band. The black band could be from some internal construction. No numbers tho. I'll post my erm, post-removal results.
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Post by justgreg on Feb 27, 2015 18:24:14 GMT -5
The diode cooks the flux right off within seconds. The cap and reg are fine. Interesting test trick Mac....guess that's why you get the big bucks. Where to next with this puppy?
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Post by justgreg on Feb 27, 2015 14:49:12 GMT -5
Sounds like a fun test. Too bad my laser thermometer is at work. A thermal camera would be a great tool too. On with the testing!
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Post by justgreg on Feb 27, 2015 12:52:31 GMT -5
I have a spare one somewhere. You thinking over voltage power surge?
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Post by justgreg on Feb 27, 2015 12:28:48 GMT -5
5.0v 2.0A
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Post by justgreg on Feb 27, 2015 0:23:50 GMT -5
Only pin 1 and 2 show short to gnd. They also have continuity when tested together.
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Post by justgreg on Feb 26, 2015 23:55:30 GMT -5
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Post by justgreg on Feb 26, 2015 23:33:08 GMT -5
Looks like it might be a 5-lead TSOT package Linear voltage regulator? I can't find the damn p/n markings in any search tho.
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Post by justgreg on Feb 26, 2015 23:12:20 GMT -5
Hmmmm...I posted the part markings from my tablet and apparently it didn't take. The pn is AN30D...looks like a D anyway. Definately not a zero. I Googled the number with a zero and a D....no go. Is it a voltage regulator?
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