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Old 6th March 2010, 04:01 PM   #1
matsj is offline matsj  Sweden
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Default Convert a 110 volt Mcintosh Mc275 to 230volt

Can someone tell me if itīs possible to convert/rewire a us 110volt Mcintosh mc275 to Europe 220 volt. I have tried asking Mcintosh but they canīt help me.

mats
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Old 6th March 2010, 04:40 PM   #2
Tomy is offline Tomy  Ukraine
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You need a transformer 220VAC to 110VAC
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Old 6th March 2010, 04:44 PM   #3
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Yes, replace power transformer with custom-build one. May not be easy task, however, if original transformer is potted.
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Old 6th March 2010, 04:45 PM   #4
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I wouldn't bother rewiring it and just get one of those yellow step-down transformers they use on building sites for their power tools many of which run on 110V for some reason.
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Old 6th March 2010, 04:52 PM   #5
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From the schematics I have seen, the MC275 has only one primary winding with a tap for 125V as well as the basic 117V. So it seems like you will need an external stepdown transformer to get from 220 to 115. Either an isolation or an autotransformer will do the job. I'm not sure if Sweden is 50 or 60 Hertz mains frequence. And I'm not sure how the MC275 (original one?) will react to 50 Hertz. The power transformer may just run a little hotter. It's a shame that McIntosh could not have provided "this" basic information. http://www.pmillett.com/file_downloa...h/MC75_sch.pdf
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Old 6th March 2010, 05:05 PM   #6
Tomy is offline Tomy  Ukraine
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Quote:
Originally Posted by HollowState View Post
I'm not sure if Sweden is 50 or 60 Hertz mains frequence. And I'm not sure how the MC275 (original one?) will react to 50 Hertz.
It work at 50 Hertz properly
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Old 6th March 2010, 05:07 PM   #7
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Quote:
Originally Posted by Charles Darwin View Post
I wouldn't bother rewiring it and just get one of those yellow step-down transformers they use on building sites for their power tools many of which run on 110V for some reason.

It would seem that many of the power tools in European use were built with the North American market in mind.

Mats, before you buy anything, look at the amp's power trafo, closely. It may have dual primaries wired in parallel. If that's the case, you are in luck and all that's necessary is to rearrange the primary setup to wired in series, instead of wired in parallel. If only a single, "115" V. primary is present, you will need a step down autotransformer. Something like Allied Electronics' 500 VA model 6K171VCP should do nicely. Shipping from North America to Europe makes little sense, but you should be able to find something similar from a reasonably local source.
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Old 6th March 2010, 05:23 PM   #8
matsj is offline matsj  Sweden
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Itīs not easy too have a close look half around the world . They are a lot cheaper in the states than here. And i can get a cheap shipping with a friend.
Some stuff are easy to rewire but i donīt know about these.

Maybe someone have had a look inside their mc275.

mats
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Old 6th March 2010, 06:31 PM   #9
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Do check your customs and duty regulations before you buy!
I was thinking about buying in the states as well at some point but everything above $20 value attracts 30% duty plus 17.5% VAT here and that makes it no cheaper than buying in a local shop.

On ebay here I can get a new 3.3kVA step-down transformer for less than Ģ45.
Most touring musicians from the US I see here use them for their big Ampeg bass amps. A friend of mine has a european spec SWR (converted to 220V by the factory) which kept dying on him until he re-converted it to 110V and started using one of those yellow transformers.

The 110V thing is a safety regulation by the way.
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Old 6th March 2010, 06:49 PM   #10
kevinkr is offline kevinkr  United States
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Quote:
Originally Posted by Charles Darwin View Post

<snip>

The 110V thing is a safety regulation by the way.
Yeah, I have a number of European friends who clued me in on this requirement long ago..(Some visitors asked me to take them to the local Home Depot - when I asked about the power issue they told me about the 120V tool requirement) I can't imagine 240V power tools in use on construction sites, frankly I find 120V tools are scary enough.. I always make sure mine are plugged into GFIs when I am using them outdoors, and if possible will do so indoors as well. For that extra measure of safety in such situations I would probably use an isolation step down transformer.. For home use heavy duty battery powered tools really are much safer..

Incidentally you should probably buy the biggest step down auto-transformer you can for this amplifier that will not trip the circuit breaker (or blow fuse) in your panel. Since the MC-275 output stage operates quite near to class B the current demand drawn from the AC line varies quite a lot with signal level and a slightly undersized step-down transformer can result in quite poor mains voltage regulation which will be reflect in the performance of the power amplifier as well.

I grew up overseas and encountered these sorts of issues and worse with auto-transformers. Northern Italy in the 1970s had mains voltages varying from 140V to 240V (mostly 50Hz, but some 25Hz hydro as well apparently) depending on where you lived and small auto-transformers were consequently ubiquitous there, despite this they unfortunately were not too reliable. (Open windings were the quite common consequence of a minor overload..)
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