Vdc Line Regulator Circuit - Epson DFX-5000+ Service Manual

Operating Principles
The +5 VDC line regulator circuit uses a ringing choke coil (RCC) system DC/DC
converter.
The rectified and smoothed DC voltage turns on the +5 VDC line first. R118 is a
starting resistor. When the +35 VDC line becomes +13 V, switching regulator IC
TL494 (IC15 1) creates a +5 V line.
The power supply board uses a 2-step rise method. When the printer is turned on,
the +35 VDC line outputs +13 VDC for 140 ms. The first rising voltage (+13 VDC)
is used to check the printhead drivers on the Cl 17 MAIN board assembly.
If a printhead driver is damaged, the control board outputs the error signal
(HIGH DRERR signal) to the power supply board. When the power supply board
receives this signal, the photo-coupler is turned on and it cuts offthe voltage of
the primary side. This prevents printhead damage when a printhead driver is
damaged. Ifthe printhead drivers are normal, the control board outputs the VPC
signal to the power supply board. When the power supply board receives this
signal, the line rises to +35 VDC after 140 ms.
2-16
Figure 2-15. +5 VDC Line Regulator Circuit
EPSON DFX-5000+ Service Manual