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If the output voltages differ from the set voltages, check if the D/A voltages supplied from the
CPU PCB are correct.
CP23 = set voltage/1.5
CP26 = set voltage/5
CP24 = set voltage/1.5
CP25 = set voltage/5
Abnormal D/A voltages suggest a defective CPU PCB.
If the D/A voltages are normal but the output voltages are incorrect, conduct the following
checks to determine if the problem is caused by an abnormality in the lens voltage
generation circuits or by an abnormality in the vacuum vessel.
Turn off the power and disconnect the MAIN CTRL-A connector J8 to break the connection
with IS CTRL-A. Turn the power back on and repeat the lens output voltage check.
If the lens output voltages differ from the set voltages, the lens voltage generation circuits
are defective and the MAIN CTRL-A PCB should be replaced.
If the lens output voltages are the same as the set voltages, the lens wiring is probably
touching the inside of the vacuum vessel. Open the door and check.
3. Checking the high-voltage power supply control circuits
EM HV circuits (-0.5 to -3kV)
Set the detector voltage and check the voltages at both CP4[V-EM] and CP2[FB-EM].
V
CP4
should be 3 x detector voltage setting (kV). Any abnormality in this voltage is probably
due to incorrect D/A voltage from the CPU PCB.
Check that when EM HV is ON, V
CP2
=V
CP4
; when EM HV is OFF, V
CP2
・
≒ 0V.
If the V
CP2
voltage is generated whether EM HV is ON or OFF, this suggests a defective
controller operational amplifier. Replace the MAIN CTRL PCB.
If V
CP2
= 0V when EM HV is ON, the problem is probably in the high-voltage power supply
assy, or in the connector cables.
CD HV circuits (-1kV to -10kV power supply)
Check the mode.
The D9 photodiode lights green in the EI mode.
If the D9 photodiode lights red or does not light, the MAIN CTRL-A PCB is probably
defective.
Check the voltages.
Set the conversion dynode voltage and check the voltages at both CP3[V-CD] and
CP1[FB-CD].
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