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Service Guide ML393/ML393CPlus
Chapter 2 Principles of Operation
2.1.05 Printhead Drive Circuit
This circuit is used to drive the twenty-four (24) print wires.
The signals HD1 through HD24 control the individual print wires. The HD ON signal (even/odd trigger)
enables the drive circuit when printing is desired.
The head drive duration is determined by an RC integrating circuit, which modifies the HD ON pulse width.
The pulse width of the HD ON signal varies with the number of pins being driven.
Printhead Drive Time
The drive time
increases
as more pins are driven.
The drive time
decreases
as less pins are driven.
The drive time also increases if the head gap lever is placed in positions 4 through 9.
An RC circuit is also used to compensate for the fluctuation of drive voltage (+38 vdc).2-1-04B.pcx
Copyright 1997, Okidata, Division of OKI America, Inc. All rights reserved. See the OKIDATA Business
Partner Exchange (BPX) for any updates to this material. (http://bpx.okidata.com)