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The Multifunction Programmable Timer (U47) outputs a variable frequency SPKR signal when the various
states have been satisfied to the System Audio Amp U2. The output of the circuit is connected to an external
speaker which emits a tone. The speaker volume can be adjusted by adjusting R8.
4.4.3 Shutter/Footswitch/Remote Interlock Circuits
Refer to pages 8-9 thru 8-10 and 8-14 thru 8-16 in Section 8. The operation of the Shutter, Footswitch, and
Remote Interlock circuits are related.
Remote Interlock refers to an external electrical jack that can be wired to a remote switch to disable
the laser. If this loop is opened the laser is disabled and a REMOTE INTERLOCK message appears on
the LCD color display. A dummy plug is supplied to directly connect across the loop if the customer
does not wire to a remote switch. The jack is located on the system back panel.
The Footswitch is a dual foot operated SPDT switch with a 12 foot cable. The user depresses one of
the two footswitches to fire the laser. The footswitch cable plugs into a jack on the back panel.
The Shutter is a solenoid operated mechanism that blocks the treatment beam path when the solenoid
is de-energized, directing the beam into a water cooled beam dump. The shutter moves out of the
beam path when the solenoid is energized. The microprocessor operates the shutter through one of its
digital I/O ports. Safety circuits can force the shutter closed with its /NOFIRE/ signal. The beam is
blocked when the shutter solenoid is de-energized. Energizing the solenoid moves the shutter out of
the beam path. The position of the shutter is monitored by two slotted optical switches. The switch
outputs are monitored by the microprocessor digital I/O and its associated safety circuits.
Refer to the Shutter/Footswitch/Remote Interlock Circuits Simplified Diagram (Figure 4.2) and to the
associated schematics in Section 8. The footswitch is connected to the +5 VDC and ground through J16-14 on
the Controller PCB. When the footswitch is not depressed, the ground is applied to the N.C. (normally closed)
return (J16-11) and the N.O. (normally open) line is open. Note that the N.C. and N.O. lines are both sensed by
the Footswitch EPLD. The microprocessor will monitor the footswitch status by way of the Footswitch EPLD.
Once the footswitch is depressed, the Footswitch Receiver inputs are grounded completing a current path
causing the FSNC1RAW or FSNC2RAW to go low. Either of these signals are asserted to the inverter U35 pin
or U35 pin 9 resulting in FSNC1 or FSNC2 signal (depending upon which footswitch is depressed) to go high.
It is then asserted to pin 14 or 27 of the Footswitch Logic EPLD U39. Providing all the signals at the EPLD is at
its proper state, the EPLD will output a /FSDOWN1/ or /FSDOWN2/ to the Safety Control EPLD U40. U39
will also output a /FSDOWN1B/ or /FSDOWN2B/ to illumine one of the two footswitch indicators LED19 or
LED0 (both green). If an error occurs, U39 will output a /FSERROR1/ or /FSERROR2/ signal illiminating
LED19 or LED20 (both red). If the Safety Control EPLD U40 is at its proper state once the footswitch is
depressed, U40 will output a low /SHUT_H_DRV/ and /GATED_SHUT_DRV/ signal to the Safety Shutter
Drive circuitry to move the shutter out of the beam path. If the footswitch is not depressed, the FSNO1RAW/
FSNO2RAW signal would go low causing U35 pin 4 or pin 8 to output a FSNO1/FSNO2 signal to go high. The
high signal is asserted to the EPLD U39 pin 16 or pin 28 resulting in the EPLD to hold the signal outputs at pins
102 and 105 high preventing U40 from moving the shutter out of the beam path.
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