Kyocera FS C5020N - Color LED Printer Service Manual page 158

2F3/2F4-3.0
Data to print is processed by the main controller PWB and transferred to the LED print head relay PWB in synchronization
with VIDEO signal through the engine controller PWB. VIDEO signal is sent from ASIC (U22) on the mail controller PWB
to ASIC (U1) on the LED print head relay PWB using LVDS method. LVDS stands for Low Voltage Differential Signaling
which uses 16 pairs of signal lines (32 in all).The main controller PWB converts VIDEO signal into a unique format using
LVDS depending on compensating data stored in a flash DIMM.
The LED print head has an EEPROM on the LPH PWB. The EEPROM includes data for compensating the fluctuation of
luminosity of every LED chip. At power-up, the compensating data in EEPROM are cached in the flash DIMM on the main
controller PWB. In a subsequent power-up, the main controller PWB refers the flash DIMM to obtain the compensating
data and the EEPROM is checked with its checksum only.
If the LED print head or the main controller PWB is replaced, checksum becomes error. The compensating data is trans-
ferred to the main controller PWB again from the EEPROM. In case of failure with EEPROM on the LPH PWB or with com-
pensating data, the printer displays service call 0951, 0952, 0953, or 0954 within approximately 30 seconds.
Drum unit
LPH PWB
EEP
ROM
LED
print head
Drum
2-1-16
LED print heads
relay PWB
ACLK, ASCLK,
AHSYNC,ASTBN
ADATA 10 to 19
ADATA 20 to 29
Figure 2-1-20 LED print head block diagram
ASIC
(U1)
LVDS
EEDATA
Serial
communication
LVDS: Low Voltage Differential Signaling
Engine
controller
PWB
VTXDP0 to 11
VTXDN0 to 11
SOUT
SIN
Serial
(U8)
communication
Main
controller
PWB
VIDEO
data
output
ASIC
(U22)
Flash
DIMM