Impingement System; Blower Motor; Blower Motor Speed Controller (Bmsc); Heater - Top - TurboChef encore Service Manual

Impingement System

The impingement system rapidly heats, filters, and
recirculates air into the cook cavity.
This section contains information about the
following components:

- blower motor

- blower motor speed controller (bMSC)

- Heater - top

- Heater - bottom

- High-limit thermostat

- Jetplate - bottom

- rTD - top and bottom

- Solid state relay (K4/K5 - Heaters)
For information on accessing and removing parts,
see the Appendix.
blower Motor
The blower motor is a brushless AC-switch
reluctance type and spins clockwise. Its top speed
is 7,100 rPM at 1 HP, and it is controlled by a
proprietary controller (see below).
blower Motor Speed Controller (bMSC)
The motor controller is proprietary and will only
operate the motor described above. It is controlled
via 0-10 VDC speed command from the control
board and can be tested in Test Mode (see page 19).
Heater - Top
The top heater is an open-coil heater rated at 3,300
watts at 208 VAC, with a resistance of 13 Ω. The
top heater is controlled by K5 of the K4/K5 solid
state relay. For testing instructions, see page 20.
Heater - bottom
The bottom heater is a sheathed-style heater rated
at 3,000 watts at 208 VAC, with a resistance of
14.4 Ω. The bottom heater is controlled by the K4
of the K4/K5 solid state relay. For testing instruc-
tions, see page 20.

High limit Thermostat

The high limit thermostat is a 250 VAC, 3-pole,
manual-reset thermostat with a trip point of 572 º F
(300 º C). The thermostat interrupts power to the
bottom or top heater in the event of an abnormal
condition. reset the high-limit thermostat by
pressing the reset button on the back oven wall,
near the power cord.
Jetplate - bottom
The bottom jetplate channels air from the blower
motor into the cavity. It is removable for cleaning.
NoTE: The top jetplate is not removable.
RTd - Top and bottom
one rTD measures the temperature of the top
heater, and another rTD measures the tem-
perature of the bottom heater. If the display reads
"999°F/C", at least one rTD is open, resulting in
an F7 fault. See page 41 for troubleshooting.
Testing Procedure:
1. Disconnect the rTD from the control
harness (see page 48 for Encore and page 62 for
Encore 2).
2. Place the rTD in ice water for two minutes.
3. Take a resistance reading of the rTD.
4. If rTD resistance is not 100 Ω (+/- 2 Ω), the
rTD is defective and must be replaced.

Solid State Relay - k4/k5 Heaters

The solid state relay is a 240 VAC, dual 40-amp
relay. K4 switches power to the bottom heater, and
K5 switches power to the top heater.

Troubleshooting

The following faults may occur in relation to the
convection system:
- F1: blower (see page page 37)
- F2: Low Temp (see page page 38)
- F6: EC Temp (see page page 41)
- F7: Thermo (see page page 41)
- F8: Heat Low (see page page 42)
The following cooking performance issues may
occur in relation to the convection system:
- Food not cooking properly (see page 45)
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