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110v to 240v transformer help needed

rob1979

New Member
hello.i was wandering if anyone can help me.i have purchased a tel-ray morley power wah boost guitar effects pedal from america which runs on 110v.i live in the uk and want to change the small transformer so it can work with 240v.i asked an electrician to have a look inside the pedal for me and he said the original transformer was single phase? and couldnt do anything with it and that id have to buy a new transformer so i rang a supplier,RS,and i told them the size of the transformer which i believe to be a chassis transformer,and that according to the schematics for the pedal its original transformer took 110v and kicked out 28v at 40ma.so i was advised on the phone by rs that the nearest transformer they had would accept 240v and dish out 15v in dual phase???? making 30v which is meant to be ok??? i have no idea at all how to wire it in place though? i have unsoldered the 2 power cables going to the pcb and fitted the new one in place but have made no attempt to fully disconnect the old transformer and wire in the new one because i dont know how to.can anyone tell me how to do this by my pictures? the pic of the transformer on its own is the new one.
http://i281.photobucket.com/albums/kk226/robbie19791979/12122009723.jpghttp://i281.photobucket.com/albums/kk226/robbie19791979/12122009722.jpg
 

RCinFLA

Well-Known Member
What they likely mean is there is two 15vac secondary windings.

This allows the transformer secondary to be configured as center tapped 30 vac, parallel the two winding to get twice the output current of one winding at 15vac, or supply two different rectifiers for two independent supplies.

It also might have two primary windings that allow it to be configured for 120v or 240v operation.
 
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mneary

New Member
Most transformers that you get at retail have a part number. Maybe you should tell us. My crystal ball broke again.

Which transformer is the new one? There's one deep in the background out of focus that is completely on its own. Another one is partly on its own with wires attached but isn't mounted. Yet another is partly on its own with no wires attached but it is bolted to the board.
 

rob1979

New Member
sorry the new one is on its own.rs catalogue number rs 503-972 which is the the one i have bolted already to the pcb but i havent fully detached the old one for fear of not knowing how to finish this lol the old one which is still partly attached has a number on top being=m98p 14-1/989 8215.hope this helps?
 

mneary

New Member
Sorry, still don't understand. The new one is on its own, that is, the one way back out of focus.

Is the one which is bolted down an alternative? It looks like it's never been used.

I'll look at the RS catalog shortly.
 
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rob1979

New Member
sorry yes the one i have bolted to the pcb is the new one.i de-soldered the two brown(live) cables so i could attache the new transformer and the loose one in my hand is the old transformer that i have not fully detached yet.the one you see in the background is a spare as i bought 2 but the one bolted to the the the pcb is the new one.
 

rob1979

New Member
thats brilliant but any idea on how to incorporate the on/off switch with the wiring to the the transformer?
 

Boncuk

New Member
Interrupt either the black or white wire and route it via the on/off switch. One wire of mains then has to go into the switch and the other one to either black or white.

That's it.

If the power switch is a DPST connect mains (L and N) to the switch and the two left over connections to black and white. Transformers are non-polarized (in this respect) and you might connect for easiest routing.

Boncuk

P.S. Schematic shows double throw switches. No single throw switches available. :)
 

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rob1979

New Member
yes the live being black goes to the switch and the white cable being american is neutral goes straight to the transformer? lol
 
you could buy a miniture transformer with all the wires included from maplins. (order code YN17T, link). you just use the brown and blue wires and put a switch in series with the brown wire. you then use the two blue wires on the other side of the transformer for 30volts (you don't use the black)
 

rob1979

New Member
thats strange as i rang maplin and told them what i was after and they told me they did not stock anything suitable the buggers! lol
 

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