advertisement


How does this work...?

N

ntom

pfm Member
Bought this audio transformer ages back.... not even sure where.

Looked at it today ready to use. Thought I'd just check it out before plugging anything in.

One mega transformer. I opened it up & disconnected the output from sockets and... 240V as expected so i'm thinking isolating transformer....

But... looking closer when re-assembled the input loops straight into the output.... I don't get it!

live in goes to transformer in & direct to live out which is connected to transformer out

neutral in goes to transformer in & neutral out and is linked to the other side of the transformer out

Whats going on...?

pictures here:

http://i782.photobucket.com/albums/yy105/ntomntom/Audio Transformer/5-3000.jpg

http://i782.photobucket.com/albums/yy105/ntomntom/Audio Transformer/1-3000.jpg

http://i782.photobucket.com/albums/yy105/ntomntom/Audio Transformer/2-3000.jpg

http://i782.photobucket.com/albums/yy105/ntomntom/Audio Transformer/3-3000.jpg
 
So effectively the transformer is shorted out.


the earth connections is made on the transformer frame, but this is also linked to an output from the secondary side.... is this a screen?
 
''effectively the transformer is shorted out'' - Looks that way if those 2 yellow wires in the black box are 'just' links (??). You will have to remove them to see what they really are...
What does it say on the side of the little box?
 
It's not an autotransformer. It got primary & secondary connections on opposite sides & it weighs a fair bit so has a large chunk of iron in it. Looks like a reasonably made piece.
 
Yep it does seem the two connections in the box are simply links which short out the transformer....

I have tried removing the links and sure enough the transformer output is 240v give or take.....across what are blue & brown wires on the secondary side.
But (also with 'jumpers' romoved) the voltage to earth is about 45v on one side & about 180v on the other.....
 
''the voltage to earth is about 45v on one side & about 180v on the other.....'' - that would be expected and is normal.
Mains Neutral should be at or close to earth potential, so you measure 240 volts to live from either. The secondary of your transformer is 'floating' (has no connection back to earth) and you are reading the induced voltages 'with respect' to earth.
 
Yep thanks that does make sense of course given the secondary is wholly isolated.

There is a yellow / green cable coming out of the secondary but I have measured it and it is not connected internally to any other cable. It is conneted externally to mains earth so I assume this is a screen connection.

So I've no idea why there are shorting tabs in this thing directly across the transformer...? They certainly look original.

There is absolutely nothing on the outside of this thing to indicate manufacturer or VA rating etc. It's not a DIY jobby. The casework is a good quality Alu casting with appropriate cutouts for three output sockets. All very neat so a manufactured item... some sort of 'boutique' type product I guess. Screened mains supply cable -Radex or similar.

All rather curious. I'll have a closer look inside & maybe unmount the transformer to see if there is any more info.....
 
Well took it apart but nothing to indicate manufacturer or anything else.

Strange!


Is ther any benefit to plugging in a huge 1:1 transformer in parallel to a socket....?

Really can't figure why there are jumpers to short it out!!
 
Could be that its for stepping from 240V to 240/230/220 but its presently on the 240 / 240
If it wasent shorted on both phases it would give some mains filtering?, strange one
Whats the other component?, is it a ballast?

Alan
 
You must log in or register to reply here.


advertisement


Back
Top