Chapter 5. Circuit Description; Circuitdescription - Sharp FO-155 Service Manual

FO-155A
FO-355A
CHAPTER5. CIRCUITDESCRIPTION
[1] Circuit description
1. General description
The compactdesignof
the
controlPWBis obtainedby
using
ROCK-
WELL fax
enginein the maincontrolsectionandhighdensityprinting
of surfacemountingpatts. EachPWBis independent a ccordingto its
function
as shownin Fig. 1.
2.
PWB configuration
Linecable
-
CCD PWB
[J
f
\ f
TEULIUPWB
Control P WB
d
(
\
L
n
L
J
ACcord
Power s upply
PWB
l—
'ane'pwB -
Fig.1
1) Control PWB
The controlPWBcontrolsperipheral P WBS, m echanical p arts,trans-
mission,andperforms overallcontrolof the unit.
This machineemploysa l-chip modem(R96SHF)whichis installed
on the controlPW13,
2)
TEULIU PWB
This PWB controls connection of the telephone line to the unit.
3)
Power supply PWB
This PWB provides voltages of +5V, +12V, and +24V to the another
PWB.
4) Panel PWB
The panel PWB allows input of the operation keys.
3. Operational description
Operational d escriptions are givenbelow:
Transmission operation
When a document is loaded
in standbymode, the state of the
documentsensoris sensedvia the 1 chip fax engine(SFE-LC).If
the sensorsignalwas on, the motor is startedto bringthe docu-
mentinto the standbyposition.With depressionof the STARTkey
in the off-hookstate,transmission takesplace.
Then,the procedureis sent out from the modemandthe motoris
rotatedto movethe documentdownto the scan line. In the scan
processor,the signalscannedby the CCD is sent to the internal
imageprocessor a ndthe ADconverterto converttheanalogsignal
into binary data. This binary data is transferredfrom the scan
processorto the image buffer within the RAM and encodedand
stored in the transmit buffer of the RAM. The data is then con-
vertedfrom parallelto serialform by the modemwherethe
serial
datais modulated andsentontothe line.
Receiveoperation
There are two ways of startingreception,manualand automatic.
Depression of the STARTkey in the off-hookmodein the caseof
manual receive mode, or Cl signal detection by the LIU in the
automaticreceivemode.
First,the SFE-LCcontrolsthe proceduresignalsfrom the modem
to be readyto receivedata.Whenthe programgoesinto phaseC,
the serialdatafrom the modemis convertedto parallelform in the
modeminterfaceof the 1 chipfax engine(SFE-LC)whichis stored
in the receivebufferof the RAM.The data in the receivebufferis
decodedsoftware-wise to reproduce it as binaryimagedatain the
imagebuffer.Thedatais DMAtransferred to the recording proces-
sor withinthe maincontrolgatearraywhichis thenconverted from
parallelto serial form to be sent to the thermalhead.The data is
printedline by line by the SFE-LCwhichis assignedto controlthe
motorrotationandstrobesignal.
Copyoperation
To makea copyon this facsimile,the COPYkey is pressedwhen
the machineis in stand-bywith a documenton the document t able
andthetelephoneset is in theon-hookstate.
First, depression of the COPYkey advancesthe document t o the
scan line. Similar to the transmittingoperation,the imagesignal
from the CCDis convertedto a binarysignalin the DMAmodevia
the 1 chip fax engine(SFE-LC)which is then sent to the image
buffer of the RAM. Next, the data is transferredto the recording
processorin the DMAmodeto sendthe imagedatato the thermal
headwhichis printedline by line.
The copying takes place as the
operation is repeated,
5) CCD PWB
ThisPWBcontrolsthepickupopticaldevice.
6) LCD PWB
This PWBcontrolsthe LCDdisplay.
5-1