Sam4s ER-280 SERIES, Service Manual

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5. Troubleshooting
5-2 SAM4S ER-280 SERIES
5-2 System Problem
End
System Problem
Reset Signal
Ok?
Y
N
1. Check the IC AME8500(U23)
2. Check the 74HC14(U10).
3. Check the RST Pattern on PCB.
Program run
Ok?
1. Check the nCS, nRD signal of EPROM nOE pin
2. Check the Addr/Data line Pattern whether it is short.
3. Replace the EPROM
N
SRAM Ok?
N
CPU
Ok?
Y
Power Fail
Signal Ok?
1. Check the LM393(U30)
2. Check the Power (+24V,+5V)
3. Check the related Circuit and Pattern on PCB
N
1. Check the nCS, nRD, nWR signal of SRAM
2. Check the VBT(Battery Volt.).
3. Check the Decoder IC 74HC138 (U15).
4. Replace the SRAM.
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
N
RTC Ok?
1. Check the RTC_SCLK & SDA signal of RTC
2. Check the VBT(Battery Volt.).
3. Check the RTC Clock 32.768KHz
4. Replace the RTC(PCF8563)
Y
Y
Y
Y
SD CARD
Ok?
1. Check the CS_SD CARD, nRD, nWR signal of SD (U27)
2. Check the clock (SD_Xiin : 7.3728MHz)
3. Check the mounted state circuit of SD pin whether pin is
open or short
N
Y