Communities

Writing
Writing
Codidact Meta
Codidact Meta
The Great Outdoors
The Great Outdoors
Photography & Video
Photography & Video
Scientific Speculation
Scientific Speculation
Cooking
Cooking
Electrical Engineering
Electrical Engineering
Judaism
Judaism
Languages & Linguistics
Languages & Linguistics
Software Development
Software Development
Mathematics
Mathematics
Christianity
Christianity
Code Golf
Code Golf
Music
Music
Physics
Physics
Linux Systems
Linux Systems
Power Users
Power Users
Tabletop RPGs
Tabletop RPGs
Community Proposals
Community Proposals
tag:snake search within a tag
answers:0 unanswered questions
user:xxxx search by author id
score:0.5 posts with 0.5+ score
"snake oil" exact phrase
votes:4 posts with 4+ votes
created:<1w created < 1 week ago
post_type:xxxx type of post
Search help
Notifications
Mark all as read See all your notifications »
Users Search
Help Dashboard Sign In Sign Up
Q&A Papers Meta
Q&A
Posts Tags Edits
Ask Question

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

Post

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

+1
−1

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.

identification repair
posted about 1 month ago
1mo ago by Nick Alexeev‭
user card
Conrado‭
14 reputation 1 1 1 2
History
Why does this post require moderator attention?
You might want to add some details to your flag.
Why should this post be closed?

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 the output of the SOT-89 chip with the 331 marking?
Nick Alexeev‭ wrote about 1 month ago
copy link

Conrado‭ Check the output of the unidentified 331 chip on the undamaged unit. Probe the voltage at the middle pin, and at the other tantalum capacitor (the East-West one). It may be a boost switcher. That would explain two things: the connection of the inductor, the diode between pins 2 and 3. If you’ve got an oscilloscope, check if any of the pins of the 331 chip are switching (pin 3 raises suspicion).

Conrado‭ wrote about 1 month ago
copy link

Nick Alexeev‭ Oh, I didn't know enough to know what I don't know yet... I didn't think to check the voltages one the intact device, and I don't have it in my hands; I only borrowed it to get the pictures of the missing components. I've ordered a capacitor to specs as explained by Lundin and a 10uh inductor on *bay; where I live in Chile postage takes about a month from anywhere, so when they get here I'll have a try at it, and then I may be able to update this post with that information about the 331.