Figure 4-7. Temperature board wave forms.
(a) On turn-on, the input to U11-D is low causing a high at U11-11.
1 Via the actions of NOR gate U10-A and the flip-flop formed by
U11-B and C, a "1" is produced at U11-4.
2 In addition, counter U2 is reset at U2-11.
3 When capacitor C14 charges up, the U2 reset line goes high
and the counter starts.
4 If the dryer and developer are not up to temperature, then
indicator DS3, "temps ready," will be off, and the timing board will get a "temp wait"
(b) During start-up, the reset line on the Temperature Ready Timer,
U2-2, toggles from low to high when the output of U11-D performs its power-up
transition. With the reset line high, the counter output is zero. This puts a "0" on