Film-Tech Forum ARCHIVE: Making SMART dimmer work on 220-240VAC

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Posted by Catalin Balaceanu (Member # 3712) on 05-26-2009, 10:15 AM:

Hey guys, I just bought a Smart Dimension 3K Tri-Level dimmer off ebay, from the US.
Where I live, we have 240VAC outlets. So, how can I switch this dimmer from 120VAC to 240VAC? The guy I bought it from, was kind enough to enclose a note inside, explaining that I need to cut the J1 jumper and place a 240v fan inside the case, in order to make it work on 240VAC. Before I proceed with that, I thought I'd better ask for a second opinion, as I reeally don't wanna fry it by mistake.

Thanks

Catalin

Posted by Oscar Neundorfer (Member # 458) on 05-26-2009, 12:00 PM:

Its been a while since I worked with these (I designed these dimmers) but I will try to remember what to do. On the pc board near the power transformer and close to the edge of the pc board (upper left corner in picture below), there are places for 3 jumpers, J1, J2, and J3. For 120V, there should be 2 jumpers in place. Remove these, and solder in a jumper in the middle position (J2). There should not presently be a jumper in that position.

If your model has a fan, then it needs to be replaced with a 240 Volt version.

The other issue has to do with 50 Hz operation. Is Romania a 50 Hz country? I do not recall testing these on a 50 Hz supply, but I believe it will work OK.

And again, this is from memory, and it has been a while since I had anything to do with these, so please check carefully to make sure things look as I have described.

Here is a link to the manual for the dimmer:
DIM 3K Manual

Posted by Catalin Balaceanu (Member # 3712) on 05-26-2009, 01:22 PM:

Thank you very much, Oscar! Yes, Romania works on 50Hz.
I located the jumpers. I never seen this kind of jumpers before, though. They look more like resistors. I'll re-use one of them and place it on the J2 spot.
I didn't find any fans when I opened the case. Probably, the guy that sold it to me, has removed it. I did find the threaded rods where a fan is suppose to be screwed on.
What do you think, could I get away with using a 12V computer case fan (prolly 80mm / 3" fan) and a 12V power supply, ofcourse?

Cheers

Catalin

Posted by Oscar Neundorfer (Member # 458) on 05-26-2009, 10:28 PM:

The jumpers are actually zero Ohm resistors, basically a piece of wire in a resistor body. You can certainly re-use one of these with no problems.

About the fan, one model had the fan and the other did not. The one we called a "THX" version had a higher inductance coil for less lamp noise, and ran a little hotter, so we put a fan in there just in case. It would really run just fine without the fan, and if you are not planning on using the full 3kW rating, you really do not need one. The SCRs and heat sink were rated for far more than the 3kW rating, and heat was not much of an issue unless you just had no air flow around the unit. As I recall, all the cases had the mounting studs for the fan. They were not always used, however.

If you will feel better with a fan, using almost any fan with an appropriate power supply should work fine.