Printronix P9212 - Hammer Bank Cooling

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Principles of Operation
Hammer Bank Cooling
The hammer driver board also powers a blower that cools the hammer bank.
A fixed 60/40 signal (PWM) is provided to the hammer driver board to run
the blower. The hammer driver board demodulates this signal to a binary
logic (on/off) signal, then drives a MOSFET that powers the blower. A
current monitoring circuit tells the RTPU when the blower is running. If the
blower is stalled or not connected, the RTPU declares a fault. (See
Figure 2–21.)
Blower
Running
Blower
Fault
48 V
Blower +
Blower –
Demodulator
Bank Fan
PWM
Figure 2–21. Hammer Bank Cooling