Wharfedale subwoofer on 220v only. How can I make this 120v?

[Gussss]

So I picked up this active subwoofer wharfedale wh D10, but it only works on 220v. Its working fine, except I don’t have 220v.

Getting an external transformer would be my last option, is there an “on board” solution, a doable one?
I haven’t been able to find schematics on this one…
The transformer is soldered to the board, but I don’t know if it is equipped with the primary 120 winding…
Any help would be appreciated…
thanks

 

[Mooly]

That is a switching type power supply and is probably designed for use in any global market (any mains voltage). Most (like a laptop PSU for example) work with no adjustment. This one may work like that with no adjustment required or it may be configurable on the board itself.

This is all hypothetical and without detailed examination its impossible to say...
Clues would be looking how those two big reservoir caps are connected. They might be configurable as a series connection for 220/240 volts and in parallel for 120 volts. That might be possible with link options on the board. Alternatively it may need no alteration and already be OK at 120 volts. Have you tried it at 120 volt?

More rarely the caps can be configured (by links) to operate in a 'voltage doubler mode' for the lower AC line voltage.

All the above is 'at your own risk, no guarantees'.

 

[Gussss]

Yeah I tried it to a 120v outlet. No luck…
But but …. Just looking a t the big caps, there is what looks like a “bridgeable” through soldering…. J1-110V

 

[Mooly]

So as suspected, it looks like it may be configurable.

Without having one in my hand to look at and draw out the circuit I can't give you definite advice other than it seems it is possible.

It might be like this.

 

[Gussss]

But it looks like these 2 gray bridges have to be removed….

 

[Mooly]

I don't think so tbh. See if your circuit matches the one I posted above. Does the centre point between the two big caps go to the '110 volt link' and from there to one of the mains input pins?

 

[Gussss]

If I understood your question, then yes…

The center point of the two big caps (if J1 is to jumpered) will go to one of the ac lines ( yellow C) ….

 

[Mooly]

It sems to be a standard arrangement then and you just fit the new link which will reconfigure the voltage doubler arrangement (as in my image). It is the usual way of doing it but I never say with 100% certainty without having the board in my hand to spin around and check for real.

Having said that I'd be reasonably sure it is OK... fit the link and power it up

 

[Gussss]

Done… fixed… thanks for the help… only J1 had to be jumpered/bridged… as you said!!!
👍🏼👍🏼👍🏼

 

[Mooly]

excellent.

 

[Osvaldo de Banfield]

Change the label on back plate to remember that now is 110V only. Otherwise, booooom.

 

[Mooly]

Good idea

I wonder if it should have a higher value fuse fitted as well. You usually double the amp rating for 115 vs 230 volt as the SMPS will draw twice the current for a given load.

 

[chrisng]

For 100-120V power supply, the fuse should be 3.15A.

 

[Gussss]

Indeed… it comes with a 1.6amp fuse…

Done…

You guys are awesome!!! Thanks for the input…

 

[Osvaldo de Banfield]

The thing lacks grounding pin in the mains plug. Thus it is a potential hazzard for you and any other rig that is grounded. In case if fault (a Y cap for example) all fault current will flow via signal cables. Be careful using it.

 

[chrisng]

This is a Class II device (not to be confused with Class 2) and does not require grounding.
https://www.moonsindustries.com/article/what-are-the-difference-between-class1-class2, class I-class II

 

[Osvaldo de Banfield]

Still it may fail.

 

[Gussss]

Nor the original 110v or the 220v, or my other subwoofers have a ground…. But do to potential hazzard, just in case, one has to be very carefull…. This is how I listen to Beethoven and Vivaldi… allways checking the temperature… you never know

by the way, it was all sarcasm. Just in case, you never know!!! Cheers