Power Supply Board; Ac Power; Dc Power - IBM 6400 Maintenance Information Manual

AC Power

Power Supply Board

The printer power supply is contained on a printed circuit board mounted in
the card cage. The power supply automatically senses and adjusts to any
commercial electrical system that provides AC mains potential in 50 or 60
Hertz systems. In other words, the printer is fully operational from available
commercial power anywhere in the world.
The power supply converts alternating current (AC) to direct current (DC) at
three voltage levels and sends the DC voltages to the controller board. The
controller board distributes all DC power to the logic and electromechanical
circuits.
AC Power
The power supply operates on AC voltages ranging from 88 to 270 V. It can
tolerate variations in frequency of 47 to 63 Hz. The power supply is designed
to withstand an AC input overvoltage of 300 VAC for one second with no
degradation of DC output voltage or damage to printer circuits.

DC Power

The power supply board contains two DC power supply systems for the
printer. The first is a +5 V bus for logic. The second consists of +48 V and
+8.5 V buses for the hammer bank and all motors.
The +5 V supply has an isolated return line that connects to the +48 V return
at the printer load. Both returns are tied together in a single-point ground. The
+5 V power supply has its own inverter, separate from the +48 V and +8.5 V
outputs.
There is an opto-isolated input on the power supply that will shut down and
latch off the +48 V and +8.5 V supplies unless it is pulled up to 5V with a 1K Ω
resistor. This resistor is mounted on the controller board and may be pulled
down or disconnected by software or internal cable interlocks. The +5 V
output will remain stable for reporting and latching the fault condition. The
return for this signal is the +5 V return. In addition, this shutdown circuit
discharges and latches the +48 V down to a level lower than 15 V in less than
200 milliseconds and requires recycling of the circuit breaker (On/Off switch)
to reset the latch.
Loss of +48 V is seen by the EC and reported as a fault.
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