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ELETTRODOMESTICI
VIA CHECCHI 98
I 21013 GALLARATE
ITALY
The F145 fault may occur in different times, given that the counter increment rate can be very different depending on the cooking
mode, the set-point temperatures, etc.:
a. In self-clean, if the short occurs at steady conditions, F145 takes 2 or 3 minutes.
b. If the short is already present when the cooking mode is activated, one cavity is set at 550°F and the opposite is idle, it
takes 15/20 minutes, more or less.
c. If the short occurs when both cavities are at steady conditions with high temperature set points, F145 takes even 1hour
before shutting down the oven heaters. Also temperature rises very slowly in this situation.
After F145 fault has occurred in self-clean mode, the latch doesn't try to unlock the door until the temperature drops down below 200°F
in both cavities. When the door unlocks, the keyboard remains locked. Keep the [Cooking Mode] key pressed for a few seconds, until
the display shows the message KBD UNLOCKED.
If a power loss occurs during a self-clean, after power recovering the control can't know if the sensors were previously shorted. The
latch auto-test cycle is suspended until the temperature drops down below 200°F in both cavities. The display shows the message
"UNLOCKING DOOR".
Pull-in voltage for relays
All the relays used to drive the heaters or the auxiliary loads are 24Vdc. The Power Boards provide the relays with a 30V
pull-in voltage pulse every 6 seconds, more or less. The relays need at least the 75% of their nominal voltage to switch on.
At steady conditions, the relay voltage is about 15V/16V that is enough to keep them on but not necessarily enough to
activate them. A problem in the electronic circuit which provides the pull-in voltage may cause the following problems:
1. The heaters sometimes switch off without following their on/off times. This can be evident when both cavities are working: the more
relays are activated, the more difficult is for the voltage supply to activate new relays on.
2. The oven is not working at the expected set point but it's working at lower temperature values in an irregular way.
3. The oven cools down even if a cooking mode is active and correctly displayed.
Off course, if such problems occur, it's necessary to replace the Power Board. As a general rule, first check the cables referring to the
tables already described.
Tuesday, June 18, 2002
BOSCH 700 SERIES:
SERVICE INSTRUCTIONS FOR OVEN TESTING AND BASIC TROUBLESHOOTING
Page 26 of 28
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