Help Convert Bryston BP-20 PS from 230v to 115v

[ainami]

I have a 230 volt version of the Bryston BP-20. The attached picture shows the transformer section of the power supply. Is it possible to re-wire this to support 115 volt US current?

I'm assuming that for 230v, points J3 and J4 (unlabeled) are wired together from the transformer.

I'm also assuming that for 115v, points J2 and J3 are wired together. Also, J1 and J4 are wired together.

This looks pretty simple, but what is the F1 component before S1 (switch)? It looks like there are two different values for 230V and 115V configurations (150maSB or 250maSB). Can someone help shed some light here?

[h_a]

F1 is a fuse; it limits power, which is P=U I, so for twice the voltage (230 vs 115) one uses a fuse for half the current, so that the product, the power, stays the same.

Have fun, Hannes

[ainami]

Excellent! Thank you.

[burbeck]

hi
to clarify omit j3, connect j1 and j2 as shown in blue, for 115V operation

[ainami]

Hi Bob,

Thanks for clarifying. That is what I assumed.

[robmil]

h_a

You can't just change a fuse and expect it to operate at a different voltage.
The primary windings of the transformer need to be either paralleled for 115VAC operation or series connection for 230vac operation.
Normally you would have 2 x 115vac primary windings on a transformer for 115 or 230vac operation.

Changing just the fuse would still mean the mains voltage would still get to the transformer EVEN if you did not do anything to the primaries. Bad if you have a 115vac unit and plug it into a 230vac supply!!