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Was doing some electrical work, plugged in a charger for an LED work light, the thing goes foof, charging is not happening so much right now.

I took the charger apart, and the only thing that looks even remotely in a post-foof state is the one pictured (the board itself appears undamaged, albeit scorched). I'm assuming it's a resistor, but I don't claim to be certain, and I don't know which size/rating. There is a black band at the bottom and a brown band at the top, and I don't think there are any bands gone missing since "the incident".

Can you identify it, so that I can replace it and see if that revives the charger? I would like that very much.

The charger is marked as "110-230V, 0.3A" with output rating of "5V 1500mA".

Photos:

Top side 1

enter image description here

top side 2

enter image description here

bottom side (component is between indicated holes)

enter image description here

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    \$\begingroup\$ Looks like a fuse, but it probably blew because something else on the board failed. \$\endgroup\$
    – John D
    Commented Oct 18, 2016 at 14:51
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    \$\begingroup\$ It IS a fuse. Look at the silkscreen: "F1" and a graphic symbol for a fuse. \$\endgroup\$
    – Tut
    Commented Oct 18, 2016 at 15:13
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    \$\begingroup\$ smells like a 10 Ohm resistor to me, that was cheaper than a fuse, but inadequate for surge charge current under load \$\endgroup\$
    – Tony Stewart EE75
    Commented Oct 18, 2016 at 15:28
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    \$\begingroup\$ The fuse is gone, but we don't know why. One thing to check for sure is each diode in the bridge rectifier (four legs, D1). It's not unusual for one or more of these to be dead short in both directions, which means a new bridge. After that you might be OK ... or not. \$\endgroup\$
    – user16324
    Commented Oct 18, 2016 at 15:53
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    \$\begingroup\$ "post-foof" - Heh :P \$\endgroup\$
    – marcelm
    Commented Oct 18, 2016 at 17:39

1 Answer 1

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You could do two separate trouble shooting:

You could try measuring the resistance on the LED block contacts to see if it is not shorted. If multimeter shows "0" resistance, it is shorted. If is it not shorted, you could try next (since the device is powered from ac power mains, you should not work with it with no experience):

The power supply's enclosure must specify the current rating of the supply. So, you need to estimate the fuse rating for replacement. Then you could try plug it in again, but without the load (no LED block). If no "foof" happens, then maybe the device is not damaged, and you could try connecting the LED block again, hoping that the first time there was some accidental temporary short.

My guess:

The text YS-388-10W indicates the model number and perhaps the output power rating 10 watt. So, if this charger works from 110V, then the current necessary to provide the 10W would be 10/110=90mA. You can try to find the fuse that is 100mA rated and try replacing the burnt one.

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  • \$\begingroup\$ It's marked as "110-230V, 0.3A" with output rating of "5V 1500mA". \$\endgroup\$
    – KlaymenDK
    Commented Oct 18, 2016 at 16:18
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    \$\begingroup\$ Find a new 0.3A 230V fuse. It does not have to be in a shape of the resistor. As long as you can properly install it on the board, you can use any shape. \$\endgroup\$
    – Nazar
    Commented Oct 18, 2016 at 16:30
  • \$\begingroup\$ I've measured across the two "exit" pads, and get a brief connection of about 80-200Ω, then no connection. \$\endgroup\$
    – KlaymenDK
    Commented Oct 18, 2016 at 21:10
  • \$\begingroup\$ You should measure the input pads of the LED block (or whatever it is), not the exit pads of the charger. \$\endgroup\$
    – Nazar
    Commented Oct 18, 2016 at 21:14
  • \$\begingroup\$ Sorry, I mis-read. The LED lamp is working fine when used with its internal battery (that I can no longer charge). Across its input pins, I get zero connection whatsoever. \$\endgroup\$
    – KlaymenDK
    Commented Oct 18, 2016 at 21:17

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