A few weeks ago someone emailed me asking me to help them convert their Baratza Virutoso to 220V operation so they could use it in Europe. I was initially hesitant.
Baratza seems like a great company and if they don't want to support 220V operation, should I be telling people to modify their products? I was also nervous to take on any liability for advising about this hack. I am pretty confident in my ability to design a modification for the circuit but I can't test it to make sure it works at all. I also don't have complete specs on every part of the device so I have no way of knowing how this modification will affect the life of the grinder. The worst thing is that I have no idea if someone reading this blog will kill themselves by following my advice.
But after mulling it over, I decided that I do want people to modify their grinders. Baratza designed a great product and I think everyone could practice useful skills and learn about good design by taking it apart, modifying it, and putting it back together. If the modification works, a whole new market would be able to enjoy a wonderful grinder while practicing some engineering skills.
Circuit and Modification
So I took apart the grinder, took pictures of each side of the circuit board, overlaid them in GIMP, and tried to decipher the circuit.
In the end, this is the best circuit I could come up with:
At the end of this post is a list of the markings I could find on each component.
I'm not entirely sure, but it seems like the 4 diodes (D1-D4) are used as a full bridge to provide DC rectification for both the control circuit and motor. The switches are in series with the mains and voltage source as I've drawn it. The triac (TR1) seems to be used to control the current coming through the motor (M1). I'm guessing the R1-C1-F1 path (and the C2 capacitor) are used to handle flyback voltage from the inductive load of the motor.
I'm not entirely sure, but I think the R2-R3-R4-R5 series is used to limit the current through the triac gate, controlling the current through the motor. If my guesses on the circuit are right, the only modification that needs to be done is to increase (double) the resistance of R2, R3, and R4. R5 can be kept as (what I'm guessing is) a 10k pot to provide current control.
I'm not quite sure, but it looks like R2-R4 are 14.7 kΩ resistors. At 110V, this would give a range of 2.21 mA to 2.72 mA to the triac, which would be about right based on the datasheet. I believe all that needs to be done is to replace the resistors with 27kΩ or 33kΩ 1/4W resistors (these are common values).
If you decide to make this modification, I take no liability for any damage that happens to you or your property. This modification is not supported by Baratza, so it will void your warranty. Please take care when working with electrical equipment. This device is used at high voltages which can lead to fire or bodily harm.
If anyone is able to successfully make this modification, please let me know! I'll be happy to update this post with what you find.
|470n K275V X2
PCX2 335M MKP
PILKOR 10 15 [40/085/21 250V]