Epson FX 1170 Service Manual - Page 118
REV.-A, Either the, Replace IC2, Table 5-5. Repairing the BOARD ASSEMBLY
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REV.-A 5.4 Repairing the Board Assembly, C094 MAIN f".+ This section provides instructions for repairing the BOARD ASSEMBLY, C094 MAIN. It describes various problems, symptoms, likely causes, checkpoints, and solutions. The checkpoint column provides proper waveforms, resistance values, and other information for each component of the C094 MAIN. Table 5-5. Repairing the BOARD ASSEMBLY, C094 MAIN Problem Symptom Cause Abnormal Dperation at power on. The CPU does not operate properly. The reset circuit is defective. Checkpoint Solution Check the voltage waveforms of the VDD (+5 V)(IC4 pin 41) and ROUT (IC4 pin 15) when the power is turned on. Replace IC4. ? -1- (CHl:Power) m ! A 1 I I I I I I 1 II I I I I I I 1 II Ill I 1 I [1 1 I I I I 1 II I I I 1 1 T + 1 CH1=2V CH2=2V [ 11 ) TIME=O. IS 1I The control ROM is not selected. Check the signal HIGH/LOW alternation (IC4 pin 4). Replace IC4. Either the ROM or the RAM is defective. CHI=2V !I TIME=lps I 1 1 Replace IC2 or IC3. 5-14
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