Optocoupler Teaser

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For starters, it looks like the transistor in the replacement is
mounted backwards.  That is, its orientation doesn\'t follow the
silkscreened image.

uses

doesn't

Upon

the

and

Well, it would help if you could supply the part numbers of the two opto couplers. Then it would help also if you could tell us what they get at their inputs. I see a 1k resistor at the left. If we assume about 10mA minimum for the opto coupler LED for it to work then you would need at least about 11.5V at the input (10mA*1k + Vled). But there is another LED, looks like it is in series with the opto coupler LED, so that would add another

1.5V, say. Do you have that much (13V) at the input? If not then you should probably replace the 1k series resistor by a lower value one.

--DF

Here is my simple take on it so far, POINT: The working one (on the right) uses a voltage divider on the input side so maybe some characteristic of the input side it was designed for makes the new/replacement one (on the left) fail immediately up energizing.

COUNTERPOINT: They both use what looks like 1/4 watt resistors and TO-92 devices which probably means we're just dealing with smaller simple signals like data transfer. Even the optocouplers I looked up on DigiKey were rated in the milliamps so I don't think the new/replacement ones are failing, they're just designed for a different application. Physically seen differences are apparent on both the input AND output side.

MURPHY'S-POINT: The boards have just one simple task, when one side is energized (yes, low power) then the other side is allowed to have IT'S energy flow (also low power). One board works and the other one doesn't. Non-working board has transistor mounted backwards from working board. Non-working board has transistor mounted backward from silkscreen image on board. Non-working board has never worked, will never work, and slipped through Brazil's (yes, that's where its made) stringent quality checks. My guy has received total of three of these replacement boards, all identical, none work.

Did they run out of NPN transistors and thought they'd use PNP and just mount it backwards?

Glad I'M not paying for the replacement boards, Bart

hmm interesting devices? i noticed A1 A2 ? these for brush motors by any chance? :) in anycase, i did notice the transistor in the left unit looks like its not in there correctly if you were to follow the board lay out?

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Real Programmers Do things like this.
http://webpages.charter.net/jamie_5

That doesn't work. You have to pull them inside out to reverse them

seen

that

swapped

Oh, I see, you call the whole board an opto coupler, I thought you meant the

6-legged components on the boards. So he swapped boards, not just components. Ah, language...

--DF

My bad...you're right, I should have called it an optocoupler interface board throughout the post. I'm still working on the exactness of vocabulary this discipline demands. Funny thing, when I WAS married my wife would blunder with words, confusing me to where I'd ask a simple question for clarification....that's when she'd exclaim with head cocked and hands on hips "You KNOW what I meant!" I never want to be like that, Bart

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Send me the bad one and $50 and I\'ll fix it and send it back to you
within a day or two.

Same thing for the replacements.