Electronics diagnostics help?

Electronics
#1

We have a new(ish) digitally controlled tacking iron that just died suddenly. Was hoping we might be able to fix it, but not sure where to start. I’m suspecting a bad capacitor, but not sure. Pics below, can bring in for more detailed look.

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PXL_20230117_194116873
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Themost suspicious bit to me is the blob of whiteish stuff that’s next to the large red part on one side, and also on the other side around the black capacitor. The capacitor side is the one that would have been facing up the majority of the time when it was plugged in.

The iron will still turn on and have the lcd work, and you can set a temperature, but it will display an error message after a minute of not heating. It would get to a set temp (150°+) in a minute or so before it stopped working.

Thanks!

#2

The white stuff is fairly common, it’s a type of silicone used to keep large components from moving. It looks like the board is covered by some residue. You could try washing with isopropyl alcohol and distilled water to see if that improves things.

#3

The “blob of whiteish stuff” is almost certainly silicone adhesive that is hold the large red part (looks like a 1 uF 250 capacitor.) The cap looks fine, though that doesn’t really prove anything. The fact that you get a display indicates it’s OK.

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

  • Warning, this thing is all dangerous voltages!
  • Do not plug it in opened up unless you really, REALLY know what you are doing

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You (we, maybe if you are noat familiar with high voltages) should be able to probe the “HT” pads (presumably the heating element) and line see voltage.

Do you have a manual for this? Can you send me a link?

Do you feel the heating element getting at all warm? Even briefly?

The solder joints on the triac look suspiciously poor. The triac is the TO-220 part (black square with metal tab and three legs on second photo partially under the red wire.)

I plan to be at DMS Wednesday and Thursday (Jan 18&19) for 6PM - 8 PM classes. We could meet before or after.

Oz

1 Like
#4

I’m not familiar with using probes for testing voltages, so help would be welcome.

No manual with the iron, and couldn’t find a link to one online. Amazon product page is here: https://www.amazon.com/dp/B07Y2X7JYW?tag=toolsmag-20

No noticeable heating occured via touch, digital readout did go up 1-2 degrees, but that could be caused by body heat since the iron was held in the palm of my hand at the time. The readout rose from 89° to 91°F over the ~minute before the error message occured.

#5

If I had to bet, it would be the heating element or the triac that controls it that has failed. Sounds like the low power electronics are trying and failing to activate heat so it’s got to be one of those two parts.

#6

Recommend not holding it in you hand when on :wink: If it’s intermittent it could get hot fast, or short you to line voltage.

So the sensor and feedback is probably fine. I’ll PM you with my cell.

Oz

#7

CAUTION! This unit does not have an isolation transformer in the circuit. There is no place to safely ground any test equipment. The Electronics Lab has an isolation transformer that should be used. Check with the folks in the Lab on how to use this item properly. The large red item (the capacitor) is part of the DC power supply. The AC power line goes through this capacitor, then gets rectified and filtered to create a low current DC power supply for the digital electronics. Sort of a cheap DC power supply without using a transformer. If the display works then the digital circuitry and this capacitor is okay. Search elsewhere for your problem.

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#8

I’ll be in Tuesday evening helping someone else if you can get together then.

#9

I’ll be in Saturday afternoon. If you can leave it somewhere where I can find it, I’ll take a look.

Oz (in DFW)

#10

I plan to be in early Thursday around 5 for a 7 pm class. If you can leave it somewhere I can find it. I’ll take a look at it.

1 Like
#11

This has changed to Saturday after lunch until a 3 PM meeting.

#12

Whatever happened with this?