Opto's not working - TechZone

Hi all,

As per the ramblings on my blog, etc, I have assembled most of my Mendel frame and am trying to finalise the electronics connections.

All 3 the axes are running fine, but the Opto's aren't. I managed to damage one as it would fit where I wanted it, so I have taken off the connectors and soldered on wires. Of the 3, the LED lights up on 2, so I reckon the other is dead. (Remember I have the TechZone ones so they light up with nothing in the path and the LED should go off when something interferes).

Putting something in the path (and I've tried all kinds of things - considering the comments made elsewhere as to suitable materials), the LED stays lit.

Can anyone please shed some light? Have I fried something on the boards with my soldering? In there a setting wrong somewhere (I'm using the 20100806 firmware). I would expect a firmware setting as I would expect this to be a hardware only issue (i.e. it doesn't react in the Opto circuit so why would the firmware have anything to do with it).

If I have fried something, while we're on the topic, I have loads of opto's out of printers I've killed over the the years, how could I determine if any of them are suitable replacements in the circuit (most of them have little circuit boards with 3 outputs on them, but i could of course remove those once I've figured out which connector is which).

I feel I'm stuck now until I get this element sorted, no point in getting on with other bits if I can't get it to run around in a 3-d mode by itself.

Thanks Craig

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[blogger.kritzinger.net]

Have you got a link to the board design, as if it is not the reprap one it is hard to say what is wrong.

If they are four pin optos perhaps they are simply inserted the wrong way round?

The firmware could make them come on permanently if the pins where configured as outputs instead of inputs.

Getting the three pin connector the wrong way round has been known to fry them.

One end of the opto is an infra red LED. If you measure the voltage across it it should be about 1.8-2V.

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[www.hydraraptor.blogspot.com]

Thanks for replying Nophead,

TechZone didn't supply a schematic. It's a very simple circuit so I will try to reverse engineer the schematic from the files they supplied on the Wiki and post it here and on my blog.

Having said that, I'm sure (but not positive) they may have been working before when I was trying the ScrapStrap.

I'll try the older version of the firmware in case some change in the current firmware has altered them from inputs to outputs. (A new setting may have been added that I didn't note - this leads me to my previous post about change notes for the firmware, but that's another topic).

I guess I probably did fry the 3rd one, so will have to make or buy another. Any suggestions re the other question I asked in respect of re-use of the loads of optos I have here?

Craig

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[blogger.kritzinger.net]

Yes you can probably use them. They usually have the resistor for the IR LED on the little PCB. They may or may not have the pull up on the output and sometimes it is a pull down and they take the signal from the emitter of the photo transistor, rather than the collector to give the opposite polarity signal.

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[www.hydraraptor.blogspot.com]

Thanks,

I shall have a play. Although tomorrow is now a Camper day, so I don't think I will make progress on this until next week.

Regards,
Craig

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[blogger.kritzinger.net]

I feel I'm stuck now until I get this element sorted, no point in getting on with other bits if I can't get it to run around in a 3-d mode by itself.

It may not be the end of the world, there are other configurations of electronics/firmware that don't use optos.

Thanks Sebastien,

I've had contact form a UK member near me who advised on a locally available replacement Opto (Electronics aren't my forte).

I've ordered bits which should arrive tomorrow, so more feedback on Sunday or Monday.

Regards,
Craig

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[blogger.kritzinger.net]