Can an audio receiver with a 130v-rated switching power supply be modified to be used without a power transformer?
If it hasn't been designed for 110 - 240 V supply then you are out of luck.







simulate this circuit &ndash; Schematic created using CircuitLab

All the switched mode power supplies rectify the mains to provide a high voltage DC supply that is fed to a transformer whose negative terminal is chopped by the switcher transistor. The capacitor(s) will charge up to √2&nbsp;*&nbsp;Vin. If it's a 120&nbsp;V supply that will be about 200&nbsp;V. Check your capacitors and you'll probably find that's all they're rated for.

For 220 - 240 V operation you would need 400 V capacitors (and rectifiers, transistors, surge suppressors, insulation - have I put you off trying yet?).