Convection Relay; Power Output Test; Cooling Fan - Viking VDSC548T Series Service Manual

Service Diagnostics and Procedures
Control Board Diagnosis

Convection Relay

When the convection element is selected by the
EOC board, 12 VDC is sent to the convection
relay coils. A red LED in front of each coil verifies
coil voltage is being sent to that particular relay.
However, this does not indicate that the relay is
functioning. When the convection element relay
is energized, (L1-black) power is sent through
the relay to the convection element (L1 power is
controlled by the line break relay).
To test, select a cooking program. When the
convection relay contact is energized (red LED lit
at base of relay), check for 240 VAC between the
yellow wire at the line break relay and the white/
red wire on P2. If 0 VAC is read, disconnect power
and remove P2 Molex plug.
Using your Ohmmeter,
check for continuity
between the two relay
contacts (refer to photo).
When the relay is not
energized, infinite ohms
should be measured. If
0 Ohms is found, this
indicates a bad relay and
the control board should
be replaced.

Power Output Test

This 4-pin connector is where output power can be
checked.
Between pin 1 and pin 4
the voltage should read
read 6.8VDC. If no voltage
in the P1 has 120 volt
input, replace the power
supply.
© 2011 Viking Preferred Service
Place meter
leads here
LED
4 pin connector

Cooling Fan

Locate the P11 connector on the control board.
The P11 connector will have a Molex plug
containing white/black wires.
P-11
With the Molex connector removed from the P11
board connection, use an Ohmmeter to measure
resistance between one of the white/black wires
and neutral at P1 on the power supply board. The
resistance should be approximately 18 . If no
resistance is read, remove fan to repair/replace
(see Cooling Fan, pages 117-118).
With the Molex connector attached to the P11
board connection, use a voltmeter to measure
voltage between the white/black wire of the
Molex plug and the white wire in the Molex plug
at the P1 power supply board. The voltage should
be 120 VAC. If 120 VAC is present and no fan
rotation, replace the cooling fan (follow cooling fan
disassembly procedure). If no voltage is present,
verify wiring. If wiring is OK, check the relay on the
EOC board.
P-11
77