4-64 Phaser 6128MFP Service Manual
General Troubleshooting
DC Power Supply Troubleshooting
LVPS Overcurrent Protection Circuit
This circuit stops all outputs if any of the Low Voltage Power Supply voltages 3.3
VDC, 5 VDC, or 24 VDC are shorted. The circuit is reset when the short is removed,
the power is turned Off, and then On again.
LVPS Overvoltage Protection Circuit
This circuit stops all outputs if the power supply voltage 3.3 VDC, 5 VDC, or 24 VDC
exceeds the specified voltage respectively. The operating point is 32 VDC or less
for 24 VDC, 7 VDC or less for 5 VDC, or 4.4 VDC for 3.3 VDC.
LVPS
Troubleshooting Reference Table
Applicable Parts Wiring and Plug/Jack Map References
■ LVPS, PL10.6.16
■ MCU Board, PL10.7.7
■ “LVPS” on page 10-14
Troubleshooting Procedure Table
Step Actions and Questions Yes No
1 Check the AC power supply (page 4-73).
Does the problem persist?
Go to step 2. Complete.
2 Turn the Power Switch Off.
Is the Fuse on the LVPS open?
Replace the
LVPS
(page 8-47).
Go to step 3.
3 1. Disconnect J501 and J502 from the
LVPS.
2. Turn the Power Switch On.
3. Measure the DC voltages between
these pins on the LVPS:
■ P501-1 <=> P501-2 = +5 V
■ P501-3 <=> P501-4 = +3.3 V
■ P502-1 <=> P502-2 = +24 V
Are all of the voltages present?
Go to step 4. Replace the
LVPS
(page 8-47).
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