With the normal (cheap) illuminator removed, slots were cut in the base opening to accept M3x16mm screws for attaching a standard 10 Watt illuminator module (available on eBay). A 12Vdc 2A supply and an in-line electronic dimmer were added to complete the inatallation. A commerically-available Series-Vi adapter ring allows use of standard Series-Vi (Series 6) photo filters if desired.
Understage Illuminator Dimmer Control/Power Supply
from optitec2020 on eBay.com