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Toroidal transformers in genelec monitors
Toroidal transformers in genelec monitors
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Old 16th February 2010, 03:24 AM   #1
Neural Ned is offline Neural Ned
diyAudio Member
Join Date: Feb 2010
Default Toroidal transformers in genelec monitors

I've got a pair of genelec 1029a monitors that I bought in Germany. I'm in the states now, and I realized recently that these monitors work on 230V only, no switch for 120V or any of that. Replacement parts aren't available anywhere that I can find, and on it is written

Toroid International AB
Transf.No. AP-53785
Made for GENELEC OY (100-2904)

IP00 ta40degC

Pictures are attached. Outside diameter is about that of the long side of a credit card. The specs say that power consumption is 80VA max.

There are three wires in, two blue one white. The resistance from blue to white is about half the resistance from blue to blue, so the white is a centertap, I take it.

There are six wires out, three pairs: grey-grey, blue-red, and white-black. The resistance of grey-grey is nearly zero. The resistance of blue-red and white-black are about the same, twenty something ohms.

I hooked the blue-blue pair up to a variac:

Voltage out of the grey-grey pairs is always nearly zero.

Voltage out of the white-black and blue-red pairs is the same for a given voltage in. I tested at a few different voltages, output is consistently about 2.36 times input... so I think I'm looking for a transformer that does 2.36 * (230/125) == 4.34 times step up.

In Out
----- -----
10.4 21.5
20.8 45
52 123
73 172

So when you get up there output voltage is consistently 2.36 times input voltage.

Anybody know where I can get some replacement transformers? Should I not do this? I have an external stepup transformer but the thing is huge and hums, it's obnoxious.

I'm trying to contact genelec, but I don't expect to have much luck.

Thanks in advance,


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Old 16th February 2010, 07:58 PM   #2
K.IlpoP is offline K.IlpoP  Finland
diyAudio Member
Join Date: Nov 2008
Please contact Genelec, Inc at www.genelecusa.com and get a spare transformers from the service dept, or send the speakers to them for service. Please note there is a thermal switch inside the trafo; this is for safety reasons. The output voltage is smaller than input voltage. If you reassemble the speaker yourself, please also note you may need a new gasket between the halves.

Best regards,

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Old 18th February 2010, 09:39 PM   #3
Neural Ned is offline Neural Ned
diyAudio Member
Join Date: Feb 2010
Duh, I had it backwards. That's what you get when you turn a noob loose with a DMM and a variac.

Dan from Genelec just got in touch with me... thanks for all the tips.

- Troy
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Old 19th February 2010, 03:39 PM   #4
Neural Ned is offline Neural Ned
diyAudio Member
Join Date: Feb 2010
Default Converting Genelec 1029a from 230V to 120V

Dan from Genelec saved the day! It wasn't clear who had him contact me... but thanks a million!

For future reference, here's the Right Way to do it: do not take them apart. There is a sticker on the back covering a hole containing a switch... see attached pictures. Press on the sticker, find the hole, open the hole with an xacto knife, pull out the black plastic plug with a pair of needlenose pliers, adjust the switch with a screwdriver. Very easy.
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File Type: jpg g2.jpg (430.4 KB, 118 views)
File Type: jpg g3.jpg (509.1 KB, 113 views)
File Type: jpg g4.jpg (459.1 KB, 109 views)
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