Functional Description, Theory of Operation

Cabinet Service Procedures

1 Functional Description

Master Control Display

Power switch

Timer: displays on row board remaining time for all active timers.

Temperature: displays on

Row Mode key row board plate temperature, alternating between top and bottom.

Timer key

Note: The illustrations for these service procedures are of the 6‐row full size UHC‐HD.

1.2 Theory of Operation

The cabinet operates on 208-250VAC 50 or 60 cycle single-phase power. The main switch activates a relay, which supplies line voltage to two distribution boards, three cooling fans and a power supply. The power supply provides 5VDC to the master control board and the distribution boards.

A ribbon cable connects the master control board to both distribution boards. Ribbon cables also connect the distribution boards to the displays. The resistance of RTD’s, attached to the heater plates, is monitored by the distribution boards. The board switches power through solid-state relays to the heater plates when the resistance, which is used as an indicator of temperature, falls out of the range for the product held in the cabinet.

The switch, relay, master control, master control board, LON board, LON filter, cooling fans and power supply are mounted under the top of the unit. The cabinet is programmed using the key pad on the front bezel.

1-1