Need help for Musical Fidelity B-1 Integrated Amp

[thanong]

Hi all,I'm very need your help.I got Musical Fidelity B-1 Integrated Amplifier with three prong plug Australia style.This amp can wiring between 240 v and 120 volt.I don't have step up transformer and I don't have circuit to wiring power transformer to 120 v.Anyone can help please.

[Mooly]

So you have a 240 volt amplifier that you want to run on 120 volts ?

It might help if you posted some detailed pictures of the transformer and its wiring.

Normally its a case of connecting either the appropriate tapping on the primary or perhaps taking two series connected windings and connecting them in parallel but you need to be sure before you do that.

[thanong]

Originally Posted by Mooly

So you have a 240 volt amplifier that you want to run on 120 volts ?

It might help if you posted some detailed pictures of the transformer and its wiring.

Normally its a case of connecting either the appropriate tapping on the primary or perhaps taking two series connected windings and connecting them in parallel but you need to be sure before you do that.

Thanks for your help Mooly, yes now its tapping in 240 volt but its can tapping to 120 volt to this is the multi volt transfomer.The primary has orange and black color wire wiring to power switch purple and white color wire are soldering together.Pink and brown wire are left free .I don't have camera to take a picture to show everyone.If someone have the circuit or have the B-1 USA version could tell the detail better than me.Thanks again Mooly.

[unclejed613]

disconnect the purple/white. connect purple to the black and connect white to orange. white and black are one winding, and orange and purple are the other winding. you know the phase relationship between the two windings because of the way they are connected now. the other open wires are 100V taps, so leave them open.

[thanong]

Originally Posted by unclejed613

disconnect the purple/white. connect purple to the black and connect white to orange. white and black are one winding, and orange and purple are the other winding. you know the phase relationship between the two windings because of the way they are connected now. the other open wires are 100V taps, so leave them open.

Thanks a lot unclejed613 for detail.I will try this weekend and will tell you later.Appriciate.

[thanong]

Originally Posted by unclejed613

disconnect the purple/white. connect purple to the black and connect white to orange. white and black are one winding, and orange and purple are the other winding. you know the phase relationship between the two windings because of the way they are connected now. the other open wires are 100V taps, so leave them open.

I reconnect as you advice.It's work now.Secondary tap 28-0-28 volt and dc 35 volt after rectifier.I played vinyl,cd,tuner for testing around 1 hrs it work fine and sound nice .But I wonder left channel 2 pair of 2n3055 power transistor ( parallel quasi-compimentary ) run hotter than right channel.I measure everything are normal.It doesn't have thermal compensator I fear it will fail later.How to measure and adjust idle current ? Thanks a lot unclejed613.

[thanong]

It work now.I measure between both emitter resistor and turn down VR-2 until multimeter show 20 millivolt power transistor run just warm and adjust VR-3 for DC of-set around 10 millivolt.I'm not sure it's correct or not,but $12.99 little amp from goodwill sound good enough for my ear.Thank you very very much unclejed613.