A valuable vocabulary lesson from ApplianceBoardRepair

The point of this blog is to dispel the confusion surrounding the nomenclature of oven control systems.

We are talking about the electronic circuit module that is generally mounted behind the control panel, containing the display which shows time and often the status of the oven. More importantly, however, control boards do exactly what their name says – they control all the functions of an oven.  They are also referred to as ERC (Electronic Range Control), EOC (Electronic Oven Control), Controller, Control Module or Assembly, PCB (Printed Circuit Board), or PC Card.

Technicians will often refer to these as clocks or timers, since the clock is a prominent feature of oven control boards. And, before electronics were introduced to home appliances, the time was kept by a mechanical clock and the oven was controlled by a separate mechanical system. The clock often failed and needed to be repaired.

Today, oven control boards fail frequently and ApplianceBoardRepair offers better repair service than anybody else! 

There are also many instances of one oven employing two or more control boards that govern different aspects of the oven. For example, there may be one board that contains the display and connects to the keypad, and there will be another board which manages the power of the oven elements and other hardware. In this case, the first board is called the Display Board, Display Head, or Control Head, and the second board is called the Power Relay Board or Appliance Manager.

We always recommend that all boards be sent in for inspection/repair if your oven is having control problems and it contains more than one board.

“How do I know if my oven has more than one board?”

Hopefully you have access to the tech sheet for your unit – sometimes they are taped to the back of the appliance. A tech sheet will contain a wiring diagram which shows all the connections between oven hardware and electronics. It will separate a display board from a power relay board should the appliance have multiple boards.

If you don’t have access to a tech sheet, don’t worry. Another easy way to tell is by identifying whether or not your control board has any relays on it. Relays are electronically controlled switches, and oven control boards generally use them to put high voltage on a heating element, among other things. These components are usually the bulkiest on a control board (aside from a transformer if your board has one). They are often black or white, and their shape is usually rectangular or boxy. They are almost always located right next to the wiring tabs where the colored wires that go to the heating elements, door latch, etc. attach.

If you don’t see anything like this on your control board, then there is an external relay board you haven’t found yet. However, the main control board (which almost always has the display) does control the relay board, and it has to connect to the relay baord to do so. There will be a wiring harness attached to the main control board which has several wires leading to the relay board. Following these wires is the easiest way to locate an external relay board. If you have a double oven with external relay boards, there is likely a relay board for each oven.

Remember, these relay board control high voltage, so if you’re digging around in your oven to find a board, MAKE SURE THE POWER IS OFF.

Lastly, there is the means by which you control your control board – the touchpad (if your control doesn’t have buttons built into the board).  This can also be referred to as the Keypad, Control Panel, Button Panel, or some other similar term.  Often, the touchpad is built into the front panel behind which the control board is mounted.  Sometimes, the touchpad is part of the control assembly.  Regardless, the touchpad and the control board are separate entities.   I’ve never seen a touchpad failure be the result of a control board problem.

What is a touchpad failure? Sometimes the control board will throw an error code: F0, F1, F7, F9, E0F2, E1F1, and  E1F2 are all common touchpad failure codes.  If the board is powered up but pressing buttons yields limited or no response, it’s likely the touchpad has failed.

Seldom can a touchpad be repaired.  The normal solution is to replace the touchpad, which generally means replacing the whole front panel.  There are two types of touchpads: Membrane Switches and Capacitive Glass.

If your panel is glass, you have the latter kind.  This sophisticated design is actually sensitive to the conductance of human skin, which manipulates an electrical field when you hold your finger to the button.  And, there’s actually no button – you just touch the labelled area of the glass to input a command.  Capacitive touchpads contain their own electronic circuit boards which create signals and send them to the main control board for interpretation. These touchpads are really nice, but also quite delicate and expensive to replaced.

Membrane Switches are an older design consisting of a number of contacts arranged in a switching matrix, such that pressing any one button creates a unique short circuit between two of many contacts on a ribbon cable that connects to the control board.  The main control microprocessor interprets each short as a specific function.  Rarely, these can be repaired, but often replacement is the only option.

ApplianceBoardRepair offers a unique line of touchpad replacement kits for select ovens, and is continuously expanding that inventory to more ovens as time goes on.  Yet, we also have the capability to modify your panel with a new touchpad that is functionally equivalent to your original in the event that your membrane switch fails and no replacements are available.

Bottom Line:

You now know the proper name for each aspect of an oven control system, and repair will help you regardless of which part has failed.