Sam4s ER-350 II SERIES, Service Manual

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6. Troubleshooting
6-2 SAM4S ER-350II SERIES
6-2 System Problems
1. Check the Reset signal.
• Check the Reset IC M51953B. (U4)
• Check the 74HC14. (U5)
2. Check the Power Fail signal.
• Check the Comparator LM393D. (U9)
• Check the +24V , +5V.
3. Check the CPU.
• Check the Clock 36.864Mhz. (X1)
• Check the +5V.
4. Check the PROGRAM.
• Check the /PSEN signal. (U23 pin number 24)
• Check the Address and Data signals
• Replace the EPROM.
5. Check the SRAM.
• Check the /CS1, CS2, /WR, /MEM_CE signals.
• Check the VBT. (Battery volt)
• Check the Decoder IC 74HC138. (U17)
• Replace the SRAM.
6. Check the RTC.
• Check the RTC_SCLK , RTC_SDA signals.
• Check the X-TAL 32.768Khz. (X2)
• Replace the RTC IC. (RS5C372A)
6-3 Display Problems
6-3-1 VFD Problems
1. Check the VDISP , VCC.
2. Check the VFD display Cable.
3. Check the control signals. (DISPLAY_CLK, DISPLAY_DATA, DISPLAY_LATCH)
4. Check the VFD PBA.
6-3-2 LCD Problems
1. Check the VLCD.
2. Check the LCD display Cable.
3. Check the control signals. (LCD_R/W, LCD_RS, CS_LCD)
4. Replace the 2Line LCD.