Ricoh A172 - Page 485

Tech Service Bulletin No. A172/A199 – 016
Page 2 of 17
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Checking Drum Ground
1.
Confirm that the Drum Shaft is grounded:
Set your meter to the 200VDC Scale and check if there is
voltage present on the Drum Shaft during a copy cycle. A normal reading is less than .5 VDC.
2. If you are reading more than .5 volts at the Drum Shaft, then take a voltage reading at CN BP
(#4
above)
on the High Voltage Supply Board – B. If this reading is more than .5 volts, then replace the
High Voltage Supply Board – B. If this reading is less than .5 volts then check and or replace the Drum
Shaft Holder and or the Drum Shaft Terminal.
3.
Confirm that the drum is grounded to the Drum Shaft
: Set your meter to the 20Ω Scale and check
resistance between the drum shaft and the edge of the drum (exposed metal). A normal reading is 5Ω
or less. If this reading is more than 5Ω then clean and or reform the Drum Grounding tabs
(#3 above)
.
NOTE1: To avoid copy quality symptoms, check that the drum is properly grounded every other PM.
NOTE2: To avoid copy quality symptoms, make sure you replace the drum lubricant bar (A1723602)
at 40k scans.
Continued…
2
CN BP on the High
Voltage Supply Board
- B
Drum Shaft
Holder
(A1094653)
Includes Drum
ground
Bearings
Drum Shaft
Terminal
(A1094655)
4
Drum grounding
tabs (inside drum)
3
Meter lead
Meter lead
Meter lead