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Pete Locke
Senior Member

Joined: 26/06/2013
Location: New Zealand
Posts: 179

Posted: 04:44am 23 Jun 2023

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Howdy clever people.
A mains transformer query.
Had an old school drum machine dropped off for repair. It's an Akai thing from the late 90's. Standard mains transformer with analogue supply. Problem was it saw 230v when the owner plugged the 120v unit in. Lucky, the only failure was the mains fuse. I offered to convert it to our 230v system, which the owner would like. No problem, I would normally grab a transformer from the pile and wind the needed secondary’s. However, this unit has an odd, very flat, and of course obsolete transformer, and no room to put a standard size replacement, or two smaller transformers for the required power. The fix for now is rewind one from the pile, and bung it in a separate box with a plug/socket to connect to the drum machine. I would like to rewind the original so the unit can be put back to normal. And so, the query.
Looking on line, and allowing for the difference between the 60Hz design, and converting it to 50Hz, has mixed answers. Varying from shouldn’t be a problem to it won’t last long, get hot, lower secondary voltages etc.
Can it be as simple as double the primary windings with half the thickness of wire, and add 17% (difference between 60 & 50Hz) to the turns counted unwinding the original primary?

Cheers
Pete' New Zealand.

phil99

Guru

Joined: 11/02/2018
Location: Australia
Posts: 1813

Posted: 05:01am 23 Jun 2023

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Yes, the textbook says that should work. If you are lucky it will just be a thermal cut out that has blown. Much easier to unwind and count the turns if it isn't an incinerated mess in there.

Godoh
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Joined: 26/09/2020
Location: Australia
Posts: 387

Posted: 08:51am 23 Jun 2023

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Maybe it would be easier to fit a switchmode supply in there rather than a transformer.
Or just use a 230 to 110 transformer to step down to suit what is in there.
Pete

Pete Locke
Senior Member

Joined: 26/06/2013
Location: New Zealand
Posts: 179

Posted: 08:38pm 23 Jun 2023

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phil99 said Yes, the textbook says that should work. If you are lucky it will just be a thermal cut out that has blown. Much easier to unwind and count the turns if it isn't an incinerated mess in there.

Thanks for that Phil. That's this weekends project. The transformer is fine, and works with 110v, so no charcoal brick to dive through :-)
Cheers
Pete'.

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