You may have an old Honeywell Electronic Air Cleaner that simply doesn't work and it's too expensive to repair. Converting it to accept a Honeywell media filter may be an affordable alternative.
First, to avoid posible injury or death, be sure to turn the power off! It's the switch in the front of the unit. Remove the cover and slide out the electronic cells.
Remove the prefilters by sliding them out.
Remove the electronic cell guide screw in the middle.
Slide in a Honeywell HEPA filter. To find your Hepa filter size, put both cells together and measure. Replace cover. Leave the power to the unit in the off position.