These different models have different prefilter sizes and use different power supply kits. They all use the same cell.

The F52 power supplies are configured based on the features offered by the model. Such as an air flow sensor or remote indicator. Some power supplies include a wiring kit.

1. Check for Shorted Cells
   A shorted cell can prevent the indicator light from coming on. Remove both cells, with door back in place operate without cells. If the unit now appears OK with indicator light ON, then the cells have a problem.
   1. Operate without cells
   2. Check cells for broken wires
   3. Check cells for bent plates
   4. Check with one cell at a time (align cell with contacts)
2. Check the Power Supply .
   If the power box is getting 120v and the Neon indicator still does not light without the cells, then the problem is in the power box compartment.
   1. Check the on/off switch, interlock door switch and wiring.
   2. Bypass the Air Flow Switch (AFS), The AFS is a sensor that signals the power supply when air flow is present. Disabling the AFS will simulate the ON state. Using a jumper wire, ground AFS resistor to the chassis, see AFS Tech Note.
      • Replace Air Flow Switch, if the Neon indicator lights and unit appears to work with the AFS disabled.
      • Replace Power Supply, if the Neon indicator does not light with the AFS disabled and no cells to short the output.
      • A neon lamp burn out is not likely if the F52 never makes a spark. The neon lamp voltage should measure 100 vdc.

The F52A-B was introduced in 1972 and has evolved in to the current F52F. The same collector cells that were used in the F52A are still used in the F52F. Thus variations of the current F52F power supply are used as the replacements for the prior F52 models.

In 1972 the F52A had an analog power supply as shown bottom-left. In 1977 the F52C F52D was released with slight changes to the cabinet.

In 1988 the F52E was released and came with a new electronic power supply that supported an optional remote indicator. The F52E would provide a terminal strip for connecting the W8600E remote indicator.

The remote indicator has 3 LEDs for ON, Fault, or Wash. The ON LED indicates the F52E is running and should only light when the blower is running. The fault LED indicates a short. The wash LED would light on excessive ionzier current.

In 1994 the F52F was introduced with an all new chassis. The F52F has new electronics. In 1998 the F52F Series 2 was released with a new optional LCD remote indicator that replaced the prior LED indicator. Also the internal power box wiring was improved with molex plug connectors. The connectors simplified manufacturing and power box repairs.