[Boatanchors] Variac low?

[StephenTetorka at cs.com]

Happy Holidays to all.

Would appreciate your comments:

Testing a low voltage power supply.
Looking for +400 VDC via full wave using 5U4.

Have its AC via a variac to bring it up slowly.
Got the DC there.
However, the AC in was only 90 VAC out from the Variac at max control.
Variac by itself 115 VAC at max control.

Put a light bulb in front of the Variac.
Got a slight glow only at full ( 90 VAC ) out into the power supply.

What's up?

Tnx,
Steve