Converting From 230v to 120v

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dantwomey

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#1
I purchased a UK CD player that uses 230v so now I have to come up with a solution to power it up. Of the many suggestion I've received I've narrowed it down to two DIY options. A.) See the schematic here. One possible option is to rewire the primary on the main transformer and replace the T902 standby transformer. B.) Is to build my own step up transformer using this https://toroid.com/Home/Product-Details/ProductID/43 and maybe this GB: Round #2; Fo-Felix EMI Filter for AC mains 120/230v; By Folsom

https://photos.google.com/photo/AF1QipMEZpduPdXsaatsSb8chq9UTILHmM21l2iNQ5BU

Regards,
Dan

P.S. I might have to attach the image of the schematic here later.
 

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#3
Hi, i would recommend you to make a custom transformer on a toroid. Converters from 220 to 120 volts or 120 to 220 are not cheap, also they produce some heat, and consume some power from mains,even your cd player is off or in standby. I saw small transformers with welded core,so not easy to dissassemble it and to rewind. Better to find similar used transformer from another cd player,maybe it can be used with some changes in connection. Or you can temporary supply this cd player with 230v someones converter,measure all output voltages ,and rewind another transformer for those voltages,use similar wire gauge for output windings.
 
#4
dantwomey said:
I purchased a UK CD player that uses 230v so now I have to come up with a solution to power it up. Of the many suggestion I've received I've narrowed it down to two DIY options. A.) See the schematic here. One possible option is to rewire the primary on the main transformer and replace the T902 standby transformer. B.) Is to build my own step up transformer using this https://toroid.com/Home/Product-Details/ProductID/43 and maybe this GB: Round #2; Fo-Felix EMI Filter for AC mains 120/230v; By Folsom

Regards,
Dan

P.S. I might have to attach the image of the schematic here later.
Click to expand...

Something like this:
100W Converter Adapter AC 110V/120V to 220V/240V Up Down Volt Transformer + EUEK | eBay
I recall a member who tried to rewind the primary and regretted it severely.
A less powerful alternative:
Step Up Voltage Converter 110 V - 220 V 45 VA US To UK Plug: Amazon.fr: High-tech
 
#6
#8
dantwomey said:
One possible option is to rewire the primary on the main transformer and replace the T902 standby transformer.
Click to expand...

Assuming the unused tap on the primary of T901 is, in fact, for 120VAC use, you may not have to replace T902. The NJU7223 regulator that runs off of T902 has a maximum input voltage of 14V. Thus for 230VAC operation, T902 could be suppling something like 12-13 volts into the '7223 and would, therefore, supply around half that under 120VAC operation. That lower voltage is within the '7223's dropout spec, so it should work.
That would make sense, because of the note on the schematic regarding fuse ratings, i.e., the "F Ver" of 630mA, which is exactly double the current of "N/K Ver." That helps me conclude that the thing was designed to work from two different primary voltages. The only question I have is whether the unused tap on T901 is for 120VAC.
Good luck,
George
 
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#9
GOR3 said:
Assuming the unused tap on the primary of T901 is, in fact, for 120VAC use, you may not have to replace T902. The NJU7223 regulator that runs off of T902 has a maximum input voltage of 14V. Thus for 230VAC operation, T902 could be suppling something like 12-13 volts into the '7223 and would, therefore, supply around half that under 120VAC operation. That lower voltage is within the '7223's dropout spec, so it should work.
That would make sense, because of the note on the schematic regarding fuse ratings, i.e., the "F Ver" of 630mA, which is exactly double the current of "N/K Ver." That helps me conclude that the thing was designed to work from two different primary voltages. The only question I have is whether the unused tap on T901 is for 120VAC.
Good luck,
George
Click to expand...

As soon as I get a chance I'll unplug the primary of T901 and take some measurements with a meter. That will give some more info on whether or not Marantz planned ahead for dual voltages. It seems quite logical to reduce manufacturing costs one would the number of unique parts to a minimum.

Regards,
Dan
 
#16
My next question to ponder is............ Does Marantz make two separate transformer boards for 230 and 120? It would be simple since they share common plugs. Just select the one need during manufacturing and plug it in. Or can I modify the existing one to use 120V. I have a suitable step-up autotransformer on the way but I'm eager to find a DIYer way. If it wasn't so complex I'd be tempted to stack a whole bunch of the mini-toroids in there!

https://www.digikey.ca/products/en?FV=ffec921d
 
#19
It can be done like this, 50VA with a 25VA transformer 🙂
The transformer has to deliver only half of the power, the other half comes directely from the power source.
115V transfo +115V source is 230V for the consuming device.
Mona
 

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