Fig. 3-20 Heater Operation Flowchart - Canon NP-70 Service Manual

3-57
sw-
"ON „
STEP 1 HO
HEATER TEMPERATURE-"LO"
~- TH 1 RESISTANCE - "HI"
~► Q40 2 - "LO"
~► Q40 6
- "HI"
~►C28 -STARTS CHARGING
STEP 2H0
C28 -CHARGES TO Q41 GATE VOLTAGE
~~ Q41 GATE - "ON"
~► Q41 - "ON"
~C28 -DISCHARGES (THRU Q41)
• TP -PULSE GENERATED
~► Q42 - "ON"
~► HEATERS - "ON" (FOR 1/2 CYCLE OF AC VOLTAGE)
•Q41 -"OFF"
~ C28 -STARTS CHARGING
STEP 3H0
HEATER TEMPERATURE - "HI"
~►THI RESISTANCE - "LO"
~►Q40 2 - "HI"
~► Q40 6 - "LO"
~. C28 -FAILS TO CHARGE TO Q41 GATE VOLTAGE
~► Q41 GATE - "OFF"
~Q41-"OFF"
~► TP - NO PULSE GENERATED
~► Q42 - "OFF"
HEATERS - "OFF" TILL HEATER TEMPERATURE "LO"
C
END
Fig. 3-20 Heater Operation Flowchart
Second Printing-June, 1974