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Crown XLS 402 Transformer


Hilary Watts

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I'm trying to repair a Crown XLS 402 amplifier where the primary of the mains transformer has failed. Unfortunately the UK distributors tell me they can no longer supply a suitable transformer. It's a toroidal transformer and so far as I can see the windings are 65v-0-65v and 18.5v-0-18.5v with the 0v point being common to both windings.

I've found several suppliers for a 65v -0-65v transformer but I havent been able to find anything with he additional 18.5v-0-18.5v winding. The low voltage winding appears to be just for the input amplifier board and speaker protection circuit so the current load is small. There might just be room in the case for a separate low voltage transformer but I'd prefer to do the job properly if possible.

 

Can anybody suggest where I can obtain a replacement or recommend a manufacturer that I can contact to find out if a custom wound transformer would be cost-effective?

Alternatively given that the amp in question has served us well for a number of years and that there has recently been the same model on Ebay which has failed to attract any bids at £100, would I be better spending the time, effort and money on acquiring a second hand amplifier? It has been used to provide the drive for stage monitors in a small theatre (musicals with a live band, dance school shows etc).

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From the Canterbury windings web site:

 

 

Type: TM172A

Continuous power rating: 550VA

Primary: 0-240V @ 50Hz

Secondary: 67-18.5-0-18.5-67V off load

Dimensions: approx 137x67mm

Mounting: mounting kit

Based on NRE Electronics XLS402D

Extended lead time on this item

 

Looks like it might have been designed for the job ;-)

Edited by alistermorton
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  • 3 weeks later...
<br />
<br />Looks like it might have been designed for the job ;-)<br />
<br /><br />Indeeed it does - the Blue Room triumphs again!<br />Thanks for that - I'll send an enquiry.<br />Hilary<br />
<br /><br /><br />

 

 

Any answer yet?

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Yeah, I had an almost identical transformer fail a year or so ago. I even managed to get hold of the original manufacturers winding details. At the time he quoted 4 months so I rewound it myself, Oh boy I have vowed I will never do that again as the effort and time involved is unreal and of course it is nowhere near as tightly wound and therefore a little larger so I was unable to fit the Mumetal screen properly.
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It took me a couple of weeks and a couple of hours a day. The big problems are the sheer amount of wire that has to be unthreaded (I re-used the secondaries), the same amount of wire to go back in which has to be pulled in tight then held tight in place as the next turn is added.

 

The pressure on the thumbs is incredible.

Edited by sunray
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