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The Something Awful Forums > Discussion > Hobbies, Crafts, & Houses > Learning electronics: Release the Magic Blue Smoke
 
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Claeaus
Mar 29, 2010
 I would like to confirm/deny my hypothesis about why this lamp stopped working.

I have this USB work light https://assets.cdn.jula.com/preset:...=19790101000000
https://www.jula.se/catalog/el-och-belysning/armaturer/arbetsbelysning/arbetslampor/batteridriven-arbetslampa-led-024720/

It runs on a rechargeable battery and charges with USB-C

A few days ago my girlfriend plugged a USB-C laptop charger into it. It ran for a minute or so and then went out and now it won't turn on. The specs for the lamp says "Input: 5V 1A" and the laptop charger says "Output: 20V 3.25A / 15V 3A / 9V 2A / 5V 2A"

So my guess is that the laptop charger gave it 5V and 2A and fried it due to too many amps?

Pictures of the disassembled lamp and of the charger: https://imgur.com/a/Dh4wOmN
I can't see anything that looks fried though. Would this be something that could be fixed with some tinkering?

* # ¿ Apr 27, 2024 21:47
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# ¿ May 13, 2024 23:15
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Claeaus
Mar 29, 2010
 Thanks for the replies!

Splode posted:

I think it could just be this - if it was switched on and charging, the LEDs probably used more current than the battery was receiving from the charger, so despite being "on charge" it went flat.

This could be because it didn't correctly ask the laptop power supply for 5V 1A with the proper USB process, so the laptop followed the USB spec and only have it 250mA. This is a common issue for cheap electronics as they don't want to pay for a chip to do USB power negotiations, so both the charger and device just offer 1A without the negotiation.

I can't think of any reason why that charger would've damaged the device though. I think it's extremely unlikely the laptop charger put out more than 5V - the USB PD spec is designed specifically to stop that happening, and USB laptop power supplies are either compliant or need to be recalled.

But shouldn't I then be able to charge it if I plug it back in? I tried with a phone charger as well but the charging LED on the lamp doesn't light up either.

* # ¿ May 2, 2024 11:22
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The Something Awful Forums > Discussion > Hobbies, Crafts, & Houses > Learning electronics: Release the Magic Blue Smoke