Honeywell Power Box for F300 F50F Series Two 16x25

Series One or Series Two

All F300A or F300E should use Series Two. All F50F F58F should use the Series Two power box unless you have the W8600E remote indicator.

The remote indicator is optional. It primarily provides the same function as the neon lamp. Ideal for installations where the unit is not seen or heard.

If you have the early W8600E indicator shown top-left, then you need the Series One power box. The Series One power box has additional circuitry for this indicator.

If you have the newest W8600F indicator, then use the Series Two power box. The Series One power box is also compatible with the W8600F when the W8600E circuitry is removed.

If you do not have either remote indicator, choose the Series Two power box. The Series One power box would be compatible but has unnecessary W8600E circuitry.

The W8600F was introduced in 1998 and was originally available in white or taupe, but the taupe was discontinued mid 2006. The W8600F is now only available in white.

Though the W8600E was replaced by the W8600F in 1998, the W8600E was available as a replacement part until 2004. We no longer have any W8600E left.

Power Box Replacement

The power box is simply removed by removing two screws. The screws are behind the access door. See pdf below:

Power Supply Inspection

First visually inspect the board. Most problems are visible such as a melted transformer winding or a burnt component such as the surge suppressors RV1 RV2.

Check the thin white ceramic resistor R3, the corner wire can break away. This can cause the collector plates to get power but not the ionizer wires.

Continuous cell sparking (for months) can burn out components or wiring. Resonant sparking causes elevated voltage swings that can break down the insulation on the high voltage wires. Check for scorching.

Often the fuse blows when the switching FET Q1 shorts, we believe from line spikes. Check the fuse continuity. A blown fuse typically reads 4.4M ohm because of circuitry in parallel.

The fuse is soldered in and not replaceable. If there is an internal short the fuse blows so to prevent any components from flaring up. Replacing a blown fuse will not fix the problem.

Honeywell does not release the circuit board schematics. Service tech's want to replace the complete board and be confident. Honeywell does not sell the discrete components. We do not do component level repair of the boards.

Replacing the complete board with a new one with a 2 year Honeywell warranty would be the most reliable repair.

Power Supply Bench Test

Here is our procedure to test the power supply board. Warning high voltage shock can cause death.

Bypass the air flow sensor to force the power supply ON by grounding the jumper resistor J8, see photo and pdf below.

Connect 120 vac to terminals P1 and P2. Check the following outputs with respect to chassis ground.

Terminal P3 will output 8.2k vdc
Terminal P2 will be 4.2k vdc
Terminal P5 for the neon lamp outputs 100 vdc

Since high voltage meters are not common, Honeywell provides the neon lamp as reliable voltage indicator. If the high voltage output falls below spec the neon lamp voltage will drop out.

Shorting P3 or P4 to ground has the same effect as the test button. The short will temporarily cause the neon indicator to go out. By tapping P3 to ground you should be able to draw an arc 1/32". Tapping P3 to ground can produce a larger arc near 3/16". These tests are without the cells connected, the arc will be twice the length with cells connected. See Spark Test Tech Note pdf.

Cell Contains 3 Contacts but Only 2 Used

You may have noticed there are 3 contacts on the cell pad but only two contacts at the power box. This allows the F50-F300 to be installed with either right or left air flow. The cell can be rotated allowing an installation with opposite air flow.

Only two contacts are used, the center contact and one end contact. Photo animation shows when the cell is rotated, the contacts maintain the correct connections.

The center contact powers the ionizing wires. The two outside contacts are connected and power the collector plates.

F300A Quick Parts Swap

If you need to replace your F50F1073 power box and would like a spare pair of cells. For the best value consider buying a new F300E1019.

All the Parts from a new F300E are fully interchangable with any prior F50F of the same size. You can swap over the power box, cells, prefilters, and door to your F50F frame. The power box mounts with two screws. The powerbox comes with 120v cord.

Warranty on Replacement Parts

The Honeywell warranty for F50 F300 Replacement Parts is 2 years. Our customers simply need to ship us the defective part. We test and confirm defective. We then ship back a brand new part at no charge.