The white wires look to be very thick and is likely to be a low output voltage. Measure the resistances between wires to determine which windings are connected.
The transformer may have twin input windings which can be connected in series for 240V or in parallel for 120V. In any case running a 240V transformer on 120V is OK but the output voltages will be halved.
When you have determined what windings are what, You could energise the highest resistance winding through a lamp limiter to find the voltage ratios. Do not kill yourself.