AFP Imaging Mini-Medical Series, Инструкция по установке, эксплуатации и сервисному обслуживанию

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Service
Mini Med Series 0000061122
Service Procedure 5-5
Theory of Operation
(Cont'd)
Solution Level Sensor
A metal screw located in the developer tank detects when the solution level becomes so
low that there is a danger of the heater becoming dry. If the developer level drops
below the end of the metal screw, the red Low Solution light will turn on to warn the
operator. When the red light is on, the heater is turned off to prevent tank damage. If an
attempt is made to run the processor, it will turn on as usual but the red Low Solution
light will begin to blink, drawing attention to the problem. When the solution level in
the tank is again at the proper level, the red light will go out and heating will automatically
resumes.
Automatic Shut-Off
The processor is preset at the factory to shut off and go into a standby mode approximately
5 minutes after the sensor(s) in the film entry lip is released by the trailing edge of the
film.
This time interval is controlled by adjusting Pot R29. R29 adjusts the frequency of an
oscillator in U6. The output of the oscillator is sent to U5 which divides the frequency
by 16,384. The oscillator is adjusted so that after division, one pulse is output by U5
after approximately 4 minutes. When the sensor is triggered by film presence, it resets
U5 to zero and holds it there. When the sensor is released, U5 again functions and
outputs its pulse after approximately 5 minutes. The output of U5 goes to a flip flop
(U4) which turns off all machine functions except solution temperature control,
recirculation pumps and one (1) dryer blower.
When the reset pushbutton is depressed, the timer is disabled and all machine functions
run continuously.
AC Interface Board
This board connects the low voltage signals from the main logic board and uses them to
switch the various AC components in the machine on and off.
The low level signals are interfaced by six optically isolated TRIAC TRIGGERS (Ul-
U7). These contain an LED which is optically coupled to a small TRIAC Trigger. The
LED in the Trigger is connected in series with the appropriate control panel LED which
indicates whether each component is operating. If either the trigger LED is bad or the
control panel LED is bad, the circuit will not operate.
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