# Transformer pri winding

I need to know how find the correct wires on a transformer with multi pri taps. I have a transformer that can work on PRI 120vac, 220vac and 250vac. There was a switch to select the proper input voltage but the switch was removed and now I am stuck. I would like to know what to do to get the transformer working on 220/250 vac. The colour of the wires that goes in on pri side from main is:

ORANGE
WHITE
BLUE
RED
BROWN
YELLOW

I hope this could help in a way. The transformer is in an audio amp. The transformer is a TAMRADIO. I don't find any data about it. I'll appreciate help. Thanks

One way to find out is to measure resistance between wires. If there is indeed an common and three taps you should measure $\dfrac{220}{120}$ the resistance between 220V and common, compared to the resistance between 120V and common. So look for ratios $\dfrac{220}{120}$, $\dfrac{250}{120}$ and $\dfrac{250}{220}$. If you measure a relatively small resistance between pins, you're probably measuring between 220V and 250V.