Sam4s ER-380F, Service Manual

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8 Troubleshooting
8-2 SAM4S ER-380M/F SERIES
8-2 System Problem
End
System Problem
Reset Signal
Ok?
Y
N
1. Check the IC M51953B(U8)
2. Check the 74HC14(U9).
3. Check the RST Pattern on PCB.
Power Fail
Signal Ok?
Program
Ok?
Y
1. Check the nCS, nRD signal of EPROM
2. Check the Addr/Data line Pattern whether it is short.
3. Replace the EPROM
1. Check the LM393(U17)
2. Check the Power (+24V,+5V)
3. Check the related Circuit and Pattern on PWB
N
N
SRAM Ok?
Y
Y
N
CPU
Ok?
Y
N
1. Check the nCS, nRD, nWR signal of SRAM
2. Check the VBT(Battery Volt.).
3. Check the Decoder IC 74HC138 (U11).
4. Replace the SRAM.
Y
N
1. Check the Clock (14.7456MHz)
2. Check the Power of CPU VCC Pin (+5V)
3. Check the mounted state of CPU pin whether the pin is
open or short
RTC Ok?
1. Check the nCS, nRD, nWR signal of RTC
2. Check the VBT(Battery Volt.).
3. Check the Decoder IC 74HC138 (U11).
4. Check the RTC Clock 32.768KHz
5. Replace the RTC(RS5C372A)