GE PP945, PP975 Operation Overview, Digital Control System, Element Control, Burner Touch Keys

Operation Overview

DIGITAL CONTROL SYSTEM

The digital control system consists of 3 circuit boards:

1.The touch board (permanently adhered to the ceramic glass panel) senses user input, including control lockout, displays user settings, contains HOT lights and key touch beeper. It is the “Main” board for the system.

2.The relay power supply module (RPSM), located inside the drop box, provides DC for touch board communications and to relays controlling the heating elements.

3.The daughter relay module (DRM) with additional relays is located under the touch board. The touch board communicates with the RPSM board via 12-volt serial bus. The RPSM communicates with the DRM via individual 5-volt and 12-volt DC levels.

There are no electronic sensors. Traditional-style sensors are located in the radiant elements providing over- temperature protection cycling and HOT lamp input to the RPSM board.

ELEMENT CONTROL

Each element is controlled by at least 2 relays. Both L1 and L2 are disconnected from the radiant elements during standby (except the HOT lamp limiter switch). The setup relays remain constantly energized during burner use. The cycle relays provide the duty cycling during non-HI settings. When non-Hi levels are selected, the burners’ cycle relay will cycle 3 times per minute. When higher levels are selected, some cycling of the element will occur due to the overtemperature limiter in the radiant element, which is in series with the relays.

BURNER TOUCH KEYS

In standby, only the ON/OFF keys (and LOCK key) should respond. The +, –, and pan-size keys should not respond until after the ON/OFF key has been touched first.

HOT LIGHT CHECK

The HOT lights are LEDs within the touch board. They are commanded "on" via serial bus responses from the RPSM board to the touch board.

A HOT light glows from two sources:

1.Whenever a burner is activated, the HOT light is immediately on.

2.When the temperature of a ribbon heating element exceeds 150°F (66°C), the HOT light is on. At temperatures over 150°F (66°C), the element's limiter switch closes, sending 240 VAC to the RPSM input at J21 and initiating the serial bus response.

When the burner is cool to the touch and in standby, the HOT light should be off. When the burner is first activated, HOT should glow immediately. If a burner has been on for approximately 1 minute (5 minutes for model JP975), then returned to standby, the HOT light should remain on until cool.

Note: Due to the low wattage rating, the warming zone surface element (JP975) will not glow red even when on highest heat setting. The warming zone surface element (JP975) does not utilize an overtemperature limiter switch.

DEMO MODE

When 120 VAC is applied to the unit between the black and red leads, the touch board will operate normally, but the relays and elements are prevented from operating.

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