Friday, April 11, 2008

Fixing/Converting Roomba adapter from 110V to 240V for New Zealand

I recently bought a Roomba 570 robotic vacuum from ebay. The robot came with a 110V/120V adapter. Since I'm pretty used to seeing adapters that support 110V-240V, I didn't bother checking the ratings and was greeted by an alarming bang and puff of yellow smoke when the adapter was plugged into our New Zealand 240V mains.

Fixing & Converting the switch-mode adapter from 110V to 240V is relatively easy but you shouldn't attempt it unless you know what you're doing. It can be very dangerous whenever working with high-voltage devices.

Opening the white adapter casing up was relatively easy (the screws are underneath the rubber feet). The yellow smoke came from a blown 200V 47uF capacitor.

To convert the adapter to 240V, you need to replace the 47uF capacitor with a higher voltage capacitor but similar capacity capacitor. I was able to get a 450V 47uF capacitor from jarcar for under $8. I would have preferred to get a capacitor with a lower voltage rating but couldn't find any local suppliers. Because of its high voltage rating, the 450V capacitor was a bit too large to mount vertically so I had to mount it sideways. I secured the capacitor from contact with other components using some blobs of hot glue. Electrolytic capacitors are polarised so make sure you make a note of which way round the original capacitor was mounted when you mount the new one.

The only other component you need to change is the varistor which is the blue disk-like component. The varistor protects the circuit from high voltage spikes. I used this one from jarcar which was under $2.

When you've finished putting the adapter back together again, plug it in and carefully measure the DC output from the circular plug (the one that goes into the docking station). The adapter should be outputting 22.5V. You shouldn't plug the adapter into the Roomba docking station until you are sure that the adapter is properly outputting 22.5V otherwise you could damage the docking station and the Roomba if it's docked.

Now for the pictures:

The adapter after it has been opened. The capacitor (top) and varistor (bottom left) have been circled. Notice how the capacitor has burst.

The replacement components. A 47F 450V electrolytic capacitor and a 275V varistor.

The original capacitor (left) and the replacement capacitor (right).

The adapter with new capacitor and varistor in place.

The adapter lid would not close because the 450V capacitor was too large. Here, the capacitor is mounted sideways.

The Roomba, happily charging from his newly converted 240V adapter.


At June 29, 2009 at 7:16 PM , Blogger Unknown said...

Hi Thanks for your post. I first tried adapting a 20v dc laptop power supply, but the roomba was unhappy it said "charging error 2"
I guess it is fussy about the right voltage.
I went to Jaycar as well and replaced the 220v cap with a 450v version, but mine fitted standing up in the correct position. Some posts regarding this modification say to just remove the varistor, but since it is there to divert voltage spikes, I thought it best to replace that as well. Either way it is important to either replace or remove the varistor, because the original one is only rated at 200v and will try to shunt the input power if you plug it into 240v.
Cheers Dave in Aus

At July 14, 2009 at 7:12 PM , Blogger Unknown said...

o Loved your fixing. I need to convert continuos 90v (30amp) to 120v. Is that possible? thanks, felipe

At December 28, 2009 at 7:07 AM , Blogger Unknown said...

Thank you very much, it helps me a lot and works for Europe as well :o) ... I just brought one from US ... I knew I need to change capacitor but totally forgot about varistor ... :o) ... Thanks!

At January 18, 2012 at 2:09 PM , Blogger Eivind said...

Just to clearify that in the original 240V adapter there is a 450V 47uF capacitor and it's large.


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