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Service Guide ML320/ML321
Chapter 2 Principles of Operation
2.2.02 Power Supply
Rev A, B, and C
The power supply consists of a power transformer, filter board and a DC power supply board.
The AC input voltage is stepped down to 8.6 VAC, 46 VAC and 10 VAC by the power transformer.
These AC voltages are converted into + 8 vdc, + 40 vdc, and + 5 vdc by the power supply board
for use throughout the printer.
Power Transformer
If the transformer temperature rises above a pre-determined level, the built-in temperature fuse
opens to prevent damage to components in the printer. Once this fuse opens, the transformer
MUST be replaced.
Filter Board
The power switch, line fuse, and line filter are mounted on the filter board.
Power Supply Board
This board transforms AC voltages into + 5 vdc, + 8 vdc and + 40 vdc for use throughout the
printer.
Rev D
The power supply consists of the power transformer, a filter board, and power supply circuitry
(located on the main controller board).
The input AC voltage is stepped down to 8.6 VAC, 46 VAC, and 10 VAC by the power transformer.
These AC voltages are rectified into + 8 vdc, + 5 vdc, and + 50 vdc levels by the DC power supply
circuitry on the main controller board.
Copyright 1997, Okidata, Division of OKI America, Inc. All rights reserved. See the OKIDATA Business
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