Yamaha AX-500

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Hi Clapster,
Hmmm, you do like to have transformer issues, don't you? ;)

You will need two transformers. One will give you your + - 60 V rails (?) and the other for your low voltage stuff. I don't know off-hand what the ratings are.

-Chris
 
Hi There Chris

I must admit , it does look a bit bad on the transformer issue , he he he , what are the chances of been given an amplifier with the exact problem as the one you have . Ive been told that this Yamaha amplifier is a very good bit of kit ( when its working ) .
Ive checked the transormer myself and i can read the high voltage but there are no low voltage readings .The transformer seems to be a bit more complicated than that of the Rotel because it is linked to a voltage selector switch at the rear.Would you be able to bypass this switch all together and use a 220v trasformer as we do not use 110v here .I hope this makes scence as im quite new to this sort of thing .

Thanks Clapster
 
clapster
Have you tried( Partstore.com ) . I did a brief search and found a mains power transformer for a AX-596,AX-550 and a RXV-396 maybe one of those might be in your ballpark!
I see no problem by-passing the selector switch if the unit is for your own personel use. I had to do that to a Yamaha CDX-930 I could get a 120 vac only I couldn't find a multi-voltage transformer.
Dave
 
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Hi Clapster,
Does the primary have a resistance reading? I have seen bad voltage selectors before as well. The secondaries may possibly short, but I doubt they would go open.

So, if you have primary continuity, measure the AC voltages on the secondaries.

This on also may burn out the 22R fuse resistor on the negative rail to front end supply, I believe they sub it with a 4R7 now, flameproof.

-Chris
 
Hi There Chris

Are you suggesting me using an EI Transformer due to the fact that the amplifier has a voltage selector switch or is it due to another reason . Sorry for all the questions but this is all so very new to me , until 2 weeks ago i did not even know what the inside of an amplifer looked like . I must say though that this forum is brilliant as what i have learnt in this short space of time from the likes of people such as yourself and many others is great and much appreciated .

Many Thanks Clapster ;)
 
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Hi Clapster,
Are you suggesting me using an EI Transformer due to the fact that the amplifier has a voltage selector switch or is it due to another reason .
Better line garbage rejection. There is nothing wrong with EI transformers and they are often passed over due to fads. The original was an EI, right?

-Chris
 
Depends what you want I'd say - to get it working, or to get it identical.

Toroids have one big advantage - they are cheaper due to being easier to wind. You will probably have great difficulty finding high VA EI transformers for sale, but no problem to find toroids.

If low voltage rails (eg 18-0-18) are required for eg preamp use, you could always build some zener referenced regulator to run from your higher main rails. Alternatively, contact some companies about having a custom toroid made. Avel Lindberg spring to mind.
 
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Hi Clapster,
My education happened during a time of books and no internet. I'm so lost with your request!

Can any member help here?

I would recommend reading up on various transformer manufacturer websites. Someone who makes both would probably give a more true viewpoint rather than someone who makes just one or the other. Hamond comes to mind.

-Chris
 
Where you can find a toroidal transformer 240V --> 50-0-50 output ?

in awatronic.fr I see any single coil 50V, but in single rail, AX-500 need 50+50 in some parts of circuit, there are some 200V diodes and 120V transistors.
Oficially the voltaje AX-500 output must be to 40-0-40 +-10%, but this type is not easily to find

the previ is suplied by the same double rail font with 43V rectifieds through 16V diodes.
 
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