Epson LQ-2550 Technical Manual page 78

2.2.5 +5 V and +12 V Supply Circuit
Figure 2-24 shows the +5 V and + 12 V supply circuit.
T1
4- — – – – — 11
— — — — — J
Pcl
This circuit outputs + 5 V, + 12 V, and –12 V. As described in the former section, this circuit also rectifies
and smoothes the energy released from the secondary side of pulse transformer T 1. The * 12 V is output
after being rectified by D8 and D9, and smoothed by C22 and C23. Fuse resistors R 19 and R22 protect
this circuit against a shorted output. R 17 and R 18 are dummy resistors, and are used to limit the rise
of the output voltage when it is open-circuited.
The + 5 V is output after being rectified by D7, smoothed by C 18, and after passing through the filter
circuit consisting of C 19, L3, and C20, so that rippIes and spikes will be eliminated.
3
, '
Figure 2-24. +5 V and +12 V Supply Circuit
C21
I
1
2-31
2
3
5
6 GL
14
4
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