RFL 9300 RFL Electronics Inc.
March 26, 1999 12 - 5 (973) 334-3100
Dual retriggerable monostable multivibrator U7 and its associated components form a 1500μs watchdog timer.
The timer is pulsed at regular 500μs intervals in 60-Hz systems, or 600μs intervals in 50-Hz systems. These
pulses are provided by the microcontroller's Port1.0 signal once during each 0.5-ms program interval. Should
the microcontroller not pulse the watchdog timer before it times out, it will deliver a 30μs reset pulse to U9
through microprocessor supervisor U8 and NAND gate U6. In the unlikely event that the watchdog timer fails to
reset U9, a backup 1.6-second watchdog timer inside U8 will reset U9.
The primary function of U8 is to monitor the +5-volt power supply, and insure that microcontroller U9 is reset
during turn-on or "brown-out" conditions. A 50-ms reset pulse is guaranteed if the supply voltage falls below 4.5
volts. Simple RC-type reset circuits can't guarantee a reset under "brown-out" conditions.
If the reset signal is active, the communications interrupt signal and all mailbox strobe lines are isolated from the
outside world. The same is true of the A/D CLOCK, PWR UP RESET, DC RESTORE, and the phase controller
trip signal. When the reset signal is low, it tri-states several input devices, including multiplexer U4, buffer/line
driver U3, and parts of inverting buffer U1 and buffer U5.
The DC RESTORE signal is applied to the ACT circuit whenever a peak change fault is detected. The signal
operates an analog switch that shorts the filter capacitor in the ACT's feedback circuit. This prevents fault cur-
rent waveforms with large amounts of dc offset from saturating the ACT input transformer.
The PWR UP RESET signal controls an analog switch that opens the secondary of the ACT's input current
transformer during power-down conditions. The transformer is switched back into the circuit during phase con-
troller initialization, and the PWR UP RESET signal remains low for the duration of phase controller operation.
Multiplexer U4 supplies the trip signal to an opto-coupler located on the test board in the display module (Sec-
tion 9). This current signal gives the trip signal good immunity against noise transients as the opto-coupler has a
slow turn-on time.
Table 12-1. Replaceable parts, phase controller modules for RFL 9300 Charge Comparison System
RFL 93B PC (Assembly No. 106370)
Circuit Symbol
(Figs. 12-3 & 12-4)
Description Part Number
CAPACITORS
C1-23,36-38
Capacitor,ceramic,0.1μF,GMV,50V,Centralab CY20C104P or equiv.
1007 1366
C24,25
Capacitor,ceramic,0.01μF,5%,100V,AVX SR301A103JAA or equiv.
1007 1645
C26,27 Capacitor,ceramic,22pF,5%,100V,AVX SA101A220JAA or equiv. 0125 12205
C28-35
Capacitor,tantalum,3.3μF,20%,35V,Kemet T322C335M035AS or equiv.
1007 1260
C39
Capacitor,tantalum,33μF,10%,10V,Kemet T322D336K010AS or equiv.
1007 1142
C40,41
Capacitor,electrolytic,47μF,+50-10%,25V,Panasonic ECEA1EV470S or equiv.
1007 1578
RESISTORS
R1-6,12,13,21 Resistor,metal film,1K,1%,1/4W, Type RN1/4 0410 1288
R7,8,11,23,26 Resistor,metal film,10K,1%,1/4W, Type RN1/4 0410 1384
R9 Resistor,metal film,5.62K,1%,1/4W, Type RN1/4 0410 1360
R10 Resistor,metal film,154K,1%,1/4W, Type RN1/4 0410 1498
R14
Resistor,metal film,15K,0.1%,1/8W,10 ppm/
o
C,Dale Type PTF56-15K0-B-T13 or equiv.
1510 2149
R15
Resistor,metal film,5K,0.1%,1/8W,10 ppm/
o
C,Dale Type PTF56-5K00-B-T13 or equiv.
1510 2145
R16,27 Resistor,metal film,5.11K,1%,1/4W, Type RN1/4 0410 1356
R17,18
Resistor,metal film,1K,0.1%,1/8W,10 ppm/
o
C,Dale Type PTF56-1K00-B-T13 or equiv.
1510 2129
R19,20
Resistor,metal film,10K,0.1%,1/8W,10 ppm/
o
C,Dale Type PTF56-10K00-B-T13 or equiv.
1510 2132
R22
Resistor,metal film,200Ω,1%,1/4W, Type RN1/4
0410 1221
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