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IC301 U-COM IC Troubleshooting
IC301 pin17, 46, 72, 90 +5V power check
YES
IC301 PIN26 5V check (POWER-SENS)
YES
X301 oscilates or not
YES
When IC301 pin11 voltage input Low©High
YES
IC301 replacement
IC501(EXPENDER IC) Troubleshooting
IC501 PIN16 +5V power check
YES
IC501 PIN2, 3 pin CLK Data check
YES
CONTROLL function check
YES
normal
NO
CN302 PIN6 DC +5.6V check
PATTERN check
NO
P-SENS refer
NO
X301 replacement
NO
RESET circuit check
NO
Troubleshooting Refer
NO
IC301 PIN3, 4 Data check (CD, TAPE FUNCTION change)
NO
IC501(BU2090F) replacement
- 2-8 -
NO
YES
Troubleshooting Refer
NO
YES
IC301 TROUBLESHOOTING refer
IC301, IC501 pattern check
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