TurboChef F3

What does TurboChef F3 mean?

F3 is displayed when the current transformer (CT) on the I/O control board detects less than 10 amps. The fault is monitored when the microwave is on during a cook cycle or in Test Mode. It clears at the onset of a cook cycle if the CT detects 10 amps or greater, or when the magnetrons are successfully energized in Test Mode. F3 terminates a cook cycle upon discovery.

Symptoms

• Display shows "F3: Mag Curr"
• Cook cycle terminates when the fault is found
• Food does not heat properly because the microwave system is underpowered
• Fault appears while the microwave is on during cooking or Test Mode

Common causes

• Blown 20-amp F3 fuse
• Defective K6 voltage relay
• Magnetron current circuit not delivering 10+ amps at the current transformer
• Faulty wiring through the current-transformer loop
• Microwave system component fault (magnetron, high-voltage transformer, diode, capacitor)

Diagnostic steps

1. 01

   Energize the magnetron circuit in Test Mode

   From Test Mode, energize the magnetron circuit and check whether 10 or more amps are present on the current-transformer wire on the control board, verifying the wire is connected through the CT loop.

2. 02

   Check the F3 fuse

   Confirm the F3 fuse is a 20-amp ATMR fuse and inspect whether it is open or blown; replace it if blown and re-verify operation.

3. 03

   Verify the K6 relay

   On U.S.-order ovens, confirm the K6 mechanical voltage relay is in good working order and replace it if defective.

4. 04

   Inspect the interlock switches

   Verify the operation of the interlock switches per the Interlock Switches procedure, since the microwave system depends on them.

5. 05

   Discharge before any microwave testing

   Disconnect AC power and discharge the high-voltage capacitors before touching the magnetron circuit, then test the magnetron only by a filament resistance test.

When to call a professional

F3 sits in the high-voltage microwave system, where the manual gives an explicit DANGER warning that testing the magnetron by any method other than a discharged filament resistance test can cause death or serious injury. High-voltage capacitors must be discharged first. This work is for a qualified service technician only; contact TurboChef Customer Support at 800.90TURBO or an Authorized Distributor rather than attempting it yourself.