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Comments on What are these mystery components (one of wire coil, another labeled "100-10L A9")?

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What are these mystery components (one of wire coil, another labeled "100-10L A9")?

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I have here an acre-counter or crop counter device like the lykketronic shown below, using two AA batteries. It arrived without working. lykketronic acre counter

Upon opening its case, I found that the PCB is missing two components, and the area where these components were is scratched, as though someone removed them carelessly.

Here is a photograph of the main PCB. The top part (cropped) is just the LCD.

PCB entire

And a close-up of the corner missing the components.

I was able to find another identical device, and the components are intact. One is a coil of wire on a black spool with a rectangular top. The other is a rectangular box labeled "100-10L A9". Here is a general view:

sane PCB

And again the close-up, including the mystery wire coil component: wire coil component

Is this wire coil a filter of some sort? An impedance? What does it do?

And what is the black box to its left? It looks like an SMD capacitor like this one at mouser, but I don't know how to interpret its label.

I am hoping to either replace or re-make the components to restore the PCB.

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4 comment threads

It arrived without working (2 comments)
[meta] component ID questions and repair questions (1 comment)
What's the output of the SOT-89 chip with the 331 marking? (2 comments)
What's connected to the [-] and [+] throughole pads? (4 comments)
What's connected to the [-] and [+] throughole pads?
Nick Alexeev‭ wrote 9 months ago

Conrado‭ There are two throughole pads south of these parts in this photo. They are marked [-] and [+] in copper. It looks like wires are soldered there. What's the purpose of these terminals? What's connected to them?

Lundin‭ wrote 9 months ago

I'm guessing the connector. And since it is a hand-held device running on batteries, voltage out to power something? Or does it use rechargeable batteries and that's voltage in?

Conrado‭ wrote 9 months ago

@Nick @Lundin Yes, those two marked + and - at the south west corner are positive and negative lines from the battery (3V, 2xAA). The one marked "P1", with the one to its left (between P1 and P3) are lines to a reed switch or something similar; every time their circuit is closed, the counter increments.

Lundin‭ wrote 9 months ago

Ok so maybe the inductor is just meant to be (part of) a filter. Then the IC could very well be a linear regulator or just a transistor.