AC/DC adapter output?

[dtaflorida]

Hi, I got a light that was originally for 220-240v. I want to replace the adapter with a 110v ac/dc adapter with outputting the correct DC voltage, but  it doesn't have any specs on it. So I opened it up to have a look inside. I did try connecting it to 24v DC and it was very dim.

 

Hopefully someone here can help me find out what the original adapter was outputting.

 

 

 

 

[Bombastinator]

The knuckle walker solution would have been to use a 110v-220v adapter on it.  Already clipped out though.  My knuckles hurt.

[dtaflorida]

1 hour ago, Bombastinator said:

The knuckle walker solution would have been to use a 110v-220v adapter on it.  Already clipped out though.  My knuckles hurt.

Oh so it would have been fine with just a plug adapter? If so then I'll just solder on a cord with a plug I can use.

[Bombastinator]

6 minutes ago, dtaflorida said:

Oh so it would have been fine with just a plug adapter? If so then I'll just solder on a cord with a plug I can use.

I thought so anyway.  Your reaction says I may be wrong though.  You may have a good reason I don’t know about.  The knuckle walking thing was intended as a statement that I didn’t really know much.

[mariushm]

Reconnect the thing as it was originally.

Get a multimeter and put it on the current range and place the multimeter leads in the right sockets for current measurement. If it has multiple ranges put it on a higher one like 1A or 10A.

Disconnect the + wire on the output and put the multimeter probes there (one probe on the ouput on the board, one connected to wire)

Now start the lamp and if it has multiple brightness levels, set it to highest. You will see on the meter the current it consumes.

Ok, now unplug it, reconnect the wires. 

Put the multimeter and probes in voltage read mode and put the probes on the plus and minus outputs of that board (or punch through the isolation of the wires)  and start the light and measure the voltage.

 

Now you know the voltage and current.

The board is very plain, basic, and probably has more parts on the back.

 

This is most likely a LED driver circuit, not a dc-dc converter, if your lamp uses leds.

This means the circuit outputs a varying amount of voltage depending on the current consumed by the leds (as leds warm up they need a bit less voltage so for example a 100mA led may need 50v at the beginning, but a few minutes later when it's hot it may need only 45v)

 

So your best bet is to measure the current. Then you can buy commercial led drivers which can be set to that current level and support output voltage within the range of your lamp's voltage.

 

Just from the pictures alone, I see

MB10s bridge rectifier converts AC to DC and it's a 0.8A part, any sane person wouldn't use it for more than 0.5A so I'd guess this lamp doesn't use more than 240v x 0.5A = ~ 100w

The big 450v capacitor is a hint the input voltage was 240v AC, if it was a 110v AC only psu a smaller 250v capacitor could have been used

The dx2866 is an offline switcher type chip with integrated mosfet/transistor (The missing pin is a hint).Dunno who makes it.

The ES1jf is a fast diode rated for max 1A, so the output current should also be under 1A

There's the 2.2uF 250v capacitor on the output of the transformer so that hints the output voltage is below 250v but that's pretty much it.

 

So output voltage could be up to 250v, and current could be less than 1A ... though transformer size makes me think it's around 10-30 watts max.

 

 

[Unimportant]

8 hours ago, dtaflorida said:

<snip>

Have you tried connecting it to 110V AC to check if it works ?

Looks like it might be a flyback current regulator design which can possibly boost voltage aswell.

[dtaflorida]

16 hours ago, Unimportant said:

Have you tried connecting it to 110V AC to check if it works ?

Looks like it might be a flyback current regulator design which can possibly boost voltage aswell.

It did turn on, but I don't know that it was as bright as it should have been. 

 

I'll try what mariushm said. I'll get around to testing it with a multimeter once I put a plug on it after the holiday.