DC42 IR probe intermittent error

  • I have this IR probe on my flashforge and when homing it has mounted the print head into the bed pretty bad a few times lately. I haven't figured out why until now when it failed and there was no detection after I put my finger under it. I then touched the single "led" a little bit and it started working again. Pushed it again and it stopped. I tested doing the same with the cap/cable/whole unit when it doesn't work and it only starts working after I touch that "led".

    Is this possible to fix or a known error? Should I contact duet3d about it or just suck it in and order a new one ^^ ?

  • administrators

    By "single led", do you mean the phototransistor with the black lens on one side of the cylindrical capacitor? If so, check the soldering at each end of it. There should be a solder fillet joining it to the PCB.

    How long have you had it, and which country are you in?

  • Yes. I will check after this print if I can spot anything without removing it from the carriege.

    the order date was 03/01/2017 but I didn't mount it before february I think. It's offset approx 33mm from the centre of the E3DV6 with bluesock on and it's not getting hot during print when I touch it after a print is completed. Is this to close and could that be the reason?

    I'm in Norway.

  • administrators

    No, that's not too close.

  • Took a while since I had to make a benchy to see if everything was working 😄 I've checked the sensor and I can't see anything wrong. I do have a broken IR probe (screwdriver accident) here so if there is a chance to replace that phototransistor with a soldering iron I could give that a go.. It's small solderings pads tho so not sure if I'm going to make it.

  • administrators

    Would you like to return the sensor to me for repair?

  • I suspect it will be cheaper to just order a new one. I can try to solder it myself if it's a chance that it will work. Is it important how the sensor is aligned?

  • administrators

    Yes, the alignment is important.

  • Ok guess I'm just going to order a new one then. Thanks for the reply.

  • administrators

    I'd be happy to repair your old one for the cost of the postage.

  • Can I send both this one and the one I broke when I showed my screwdriver through the resistors (a old post you replied to)? Where should I send it? I can check what postage cost from my place and if it's not to bad I'll send them as a letter once I get my new one.

  • administrators

    Sure, but I may not be able to mend the other one, it depends on the damage.

  • I did order a new sensor and was planning on doing a swap today. When I took out the old one I spotted a broken soldering on the sensor I had to push to get it working again. You can see it right below the cap in this picture. Soldered it up and it works good again giving consistant measurement and doesn't seem to drop out. As a feedback dc42 it would be smart with some more solder on this sensor as this would not have happend if it was thicker amount of thin on it like with the other SMD mounted parts.

    The other sensor are missing a diode, a resistor and a cap if I'm not wrong all SMD mount. You can see a clear scratch where I pushed my screwdriver down so this is user error for sure but I was wondering if you had these components and could drop them in a envelope for me if the shipping isn't expensive ^^ I don't really need a third sensor but when I first got it it doesn't hurt to fix it up 😄

  • administrators

    There was a batch of IR sensors made several months ago which had faulty soldering on the phototransistor in a few instances, the same as in your photo. After that we added an extra visual inspection step to check that soldering.

    Minim, send me a PM with your address and I'll put the LED and the resistor in the post to you. The capacitor isn't needed, we stopped fitting it on recent batches.

  • Ah all solved then 🙂 I'll throw on a blob of solder on the one I need to replace the resistor/led on also just as a safety measure. Both were bought at the same time.

    Thank you for that. PM sent. Is there any chance I could have damaged something else on the card if it was powered after those components where off? If you look closely it looks like the sensor is burned/brown on one of the ends if I compare it to the one I just soldered on. I can't recall if I tested it after I broke it during mounting.

  • administrators

    I doubt that anything else has been damaged. The brown tinge is probably excess flux left over from touching up the soldering on the phototransistor by hand after the visual inspection I mentioned.

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