Citizen CT-S851 User manual

Service Manual
COMPACT LINE THERMAL PRINTER
CT-S851 Series
Revision 1.00 2010.2.25

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REVISIONS
Rev No. Date Page Comment
1.00 2010/2/25 Newly issued
CITIZEN is a registered trademark of CITIZEN HOLDINGS CO., LTD., Japan.
CITIZEN es una marca registrada de Citizen Holdings Co., Japón.

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CONTENTS
INTRODUCTION .............................................................................................4
1. DISASSEMBLY AND REASSEMBLY.......................................................4
1-1. Tools Used .........................................................................................................................4
1-2. Disassembly Procedure .....................................................................................................5
1-2-1. Disassembling the Printer....................................................................................5
1-2-2. Disassembling “UNIT, MECHANISM” ................................................................14
1-3. Assembly Procedure........................................................................................................23
1-4. Oiling................................................................................................................................24
2. TROUBLESHOOTING ...........................................................................27
2-1. Error Indication.................................................................................................................27
2-2. Explanations of Error Conditions......................................................................................28
2-2-1. Paper Near End.................................................................................................28
2-2-2. Paper End..........................................................................................................28
2-2-3. Front Cover Open..............................................................................................28
2-2-4. Paper Cover Open.............................................................................................28
2-2-5. Cutter Error........................................................................................................28
2-2-6. Black Mark Error................................................................................................28
2-2-7. Print Head Hot ...................................................................................................28
2-2-8. Memory Error.....................................................................................................28
2-2-9. Print Head Error.................................................................................................29
2-2-10. Motor Error ........................................................................................................29
2-2-11. Low Voltage Error ..............................................................................................29
2-2-12. High Voltage Error .............................................................................................29
2-2-13. Drawer Voltage Error .........................................................................................29
2-2-14. Macro Execution Wait........................................................................................29
2-3. Troubleshooting Procedure..............................................................................................30
2-4. Troubleshooting Guide.....................................................................................................30

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3. SERVICE PARTS LIST ..........................................................................34
3-1. Mechanical Parts List.......................................................................................................34
3-1-1. Mechanical Exploded Diagrams ........................................................................40
3-2. Parts Layout.....................................................................................................................47
3-2-1. SA, MAIN PCB ..................................................................................................47
3-2-2. SA, DC PCB ......................................................................................................49
3-2-3. SA, SERIAL I/F PCB..........................................................................................49
3-2-4. SA, PARALLEL I/F PCB.....................................................................................50
3-2-5. SA, USB I/F PCB...............................................................................................50
3-2-6. SA, USB HUB I/F PCB ......................................................................................51
3-2-7. SA, POWERED USB I/F PCB ...........................................................................51
4. CIRCUIT DIAGRAMS.............................................................................52
4-1. MAIN PCB .......................................................................................................................52
4-1-1. Main Control Board (CPU1)...............................................................................52
4-1-2. Main Control Board (CPU2/DAC) ......................................................................53
4-1-3. Main Control Board (ROM) ................................................................................54
4-1-4. Main Control Board (RAM) ................................................................................55
4-1-5. Main Control Board (GATE_ARRAY).................................................................56
4-1-6. Main Control Board (HEAD, OP-PANEL)...........................................................57
4-1-7. Main Control Board (PF MOTOR)......................................................................57
4-1-8. Main Control Board (SENSOR) .........................................................................58
4-1-9. Main Control Board (POWER/DRAWER/BUZZER)...........................................59
4-1-10. Main Control Board (IF PCB CON / OPTION IF) ...............................................60
4-1-11. Main Control Board (CUTTER) ..........................................................................61
4-2. PE, PNE Sensor ..............................................................................................................62
4-3. Operation Panel ...............................................................................................................62
4-4. Serial I/F PCB ..................................................................................................................63
4-5. Parallel I/F PCB ...............................................................................................................64
4-6. USB I/F PCB....................................................................................................................65
4-7. USB HUB I/F PCB ...........................................................................................................66
4-8. POWERED USB I/F PCB ................................................................................................67

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INTRODUCTION
This manual describes the disassembly, reassembly, and maintenance procedures of CT-S851 Series.
1. DISASSEMBLY AND REASSEMBLY
Note the following items when performing maintenance of the printer.
•Do not disassemble, reassemble, or adjust the printer unnecessarily when the printer operation is
satisfactory.
•Do not loosen the screws that fasten the components unless it is absolutely necessary.
•After finishing inspection, perform a check to ensure that there is no irregularity before turning on the
printer.
•Use caution not to leave any part or screw used for maintenance inside the printer.
•When handling the print head and electronic components, care must be taken to avoid static electricity.
•When disassembling or reassembling the printer, check the wires and cords for damage. Do not draw
any wire or cord by force.
•Lubricate the components as necessary when reassembling them.
1-1. Tools Used
•Phillips screwdriver #0, #1, and #2
•Tweezers
•Long-nose pliers
•Brush

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1-2. Disassembly Procedure
1-2-1. Disassembling the Printer
1. Disassembling “UNIT, I/F PCB”
Remove two “SCREW, BHT (ST), M3.0 ×6” that fasten “FRAME, BOTTOM” and “UNIT, I/F PCB”.
2. Disassembling “SA, COVER-02”
Push “KNOB, COVER OPEN -02” upward and open “SA, COVER-02”.
Remove three “SCREW, BHT (PT), M3.0 ×10” and remove “SA, COVER-02” from “COVER, FRAME”.
Hold “HOLDER, DAMPER PAPER-02” by hand until two screws come into view, and remove the two
screws.
SCREW, BHT (ST), M3.0 ×6
KNOB, COVER OPEN-02
SCREW, BHT (PT), M3.0 ×10
HOLDER, DAMPER
PAPER-02

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Since “SA, COVER-02” is secured with hooks and the boss, it cannot be removed easily when it is fully
opened. To remove “SA, COVER-02”, slightly close it by hand, raise its front edge, and slide it
backward.
When mounting “SA, COVER-02”, align the boss with the hole at “COVER, FRAME” and slide “SA,
COVER-02” upward with hooks inserted into “COVER, FRAME”.
<Precaution at disassembly / reassembly>
The hooks and the boss at “SA, COVER-02” are engaged on “FRAME, COVER”. Carefully disassemble or
reassemble the components so as not to damage them. Check the routing of “SA, HEAD CABLE-02”.
Hooks
Boss
OK
NG

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3. Disassembling “SA, HEAD COVER”
Detach the lugs from the notches at the right and left sides of “COVER, FRAME”, and move down “SA,
HEAD COVER” and pull it out with care so as not to damage the lugs.
<Precaution at reassembly>
Hang the hooks at “SA, HEAD COVER” on “COVER,
FRAME” and raise “SA, HEAD COVER” using these
hooks as fulcrums. Let the bosses at the right and left
sides of “SA, HEAD COVER” fit into the holes at
“COVER, FRAME”, and engage the lugs to secure “SA,
HEAD COVER”.
4. Disassembling “SA, THERMAL HEAD-02”
Move down “HOLDER, HEAT SINK-02” by pressing the edges at the right and left sides. “SA,
THERMAL HEAD-02” is detached from lugs at “COVER FRAME”.
Pull “SA, THERMAL HEAD-02” out from “SHAFT, HEAD ADJUST-2” along the U-slot, and disconnect
“HEAD CABLE” from two positions.
SA, HEAD COVER
Bosses at right
and left sides
Lugs at right
and left sides
Hooks
HOLDER, HEAT SINK-02
Lugs at “COVER, FRAME”
SHAFT, HEAD ADJUST-2
HEAD CABLE
BOSS
Heating section at “SA,
THERMAL HEAD-2”
U-slot

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<Precaution at reassembly>
“SA, THERMAL HEAD-02” is electrostatically sensitive.
Avoid contacting the heating section.
When reassembling, insert the U-slot into “SHAFT, HEAD
ADJUST-2”, and let the bosses fit into “SPRING,
HEAD-02”. Press the both sides at “HOLDER, HEAT
SINK-02” and engage the lugs at “COVER, FRAME” on
“HOLDER, HEAT SINK-02”.
5. Disassembling “SA, PLATEN UNIT-02”
Raise “HANDLE, PLATEN-02” on both sides, and pull “SA, PLATEN UNIT-02” out from “SA, MAIN
FRAME”.
6. Disassembling “SA, CUTTER UNIT-02”
Push “PIN, FRONT COVER” at the right side of “SA, CASE-02” using a sharp-pointed tool. Raise
“FRONT COVER-02” and flip it down toward you to open it. When “LEVER, CUTTER RELEASE-02” at
the right and left sides are pushed down, “SA, CUTTER UNIT” pops out. Pull it out upwardly and
disconnect cables from the connector.
Align the bosses with
“SPRING, HEAD-02”.
HANDLE, PLATEN-02
SA, PLATEN UNIT-02
LEVER, CUTTER RELEASE-02
Connector

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7. Disassembling “SA, FRONT COVER-02”
Remove two “SCREW, BHT (ST), M3.0 ×6” that fasten “SA, FRONT COVER-02” and “SA, MAIN
FRAME” and disconnect “SA, OPEPANE CABLE F” from the connector.
Remove “HOLDER, FRONT COVER-02” from “SA, FRONT COVER-02”.
Remove “HOLDER, FRONT COVER-02” while pulling its side edge outwardly.
8. Disassembling “SA, CASE-02”
Remove two “SCREW, BHT (ST), M3.0 ×6” that fasten “SA, CASE-02” and “SA, MAIN FRAME”.
Raise the front edge of “SA, CASE-02” while slightly pressing “POWER SW” at the front.
SCREW, BHT (ST), M3.0 ×6 SA, OPEPANE CABLE F SA, FRONT COVER-02
HOLDER, FRONT COVER-02
SCREW, BHT (ST), M3.0 ×6

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Close “SA, COVER FRAME” slightly, and raise “SA, CASE-02” while pulling the right and left edges of
“SA, CASE-02” outwardly. When “SA, CASE-02” is raised slightly, release “SA, COVER FRAME” and
raise “SA, CASE-02” further while pulling the right and left edges outwardly and keeping the lugs at the
rear clear of “FRAME, BOTTOM”.
Raise “SA, CASE-02” along “SA, COVER FRAME”. When “SA, CASE-02” is raised to the position
indicated in the photo below, turn it counterclockwise and pull it upwardly to remove it.
<Precaution at disassembly / reassembly>
Do not assemble or disassemble “SA, CASE-02” by force. When removing “SA, CASE-02”, raise it little by
little. When reassembling, follow the disassembly procedure in reverse. Face the front panel of “SA,
CASE-02” to the right, pass it through “SA, COVER FRAME”, and turn it clockwise. When the front faces
toward you, pull the right and left panels of “SA, CASE-02” outwardly and keep the lugs at the rear clear of
“FRAME, BOTTOM”. Push “SA, CASE-02” downward while closing “SA, COVER FRAME”.
SA, COVER FRAME
SA, CASE-02
Be sure to keep lugs at the right and left
sides clear of “FRAME BOTTOM”.

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Remove “SA, OPEPANE CABLE-F” and “SA, CUTTER CABLE”.
9. Disassembling “COVER,
ADAPTER”
Remove four “SCREW, BHT (ST), M3.0 ×
6” that fasten “COVER, ADAPTER” and
“FRAME, BOTTOM”.
Remove the AC adaptor cable from the power connector.
(Note that this connector is of the lock type.)
<Precaution at disassembly / reassembly>
The power connector is a lock-type connector. Unlock the connector by pulling the outer slide at the end of
the connector to disconnect the cable. When fitting the connector, insert it until it clicks and ensure that it
cannot be removed easily.
J17: SA, CUTTER
J3: SA, OPEPANE
SA, CUTTER CABLE
SA, OPEPANE CABLE-F
SCREW, BHT (ST), M3.0 ×6

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10. Disassembling “FRAME, BOTTOM”
Remove four “SCREW, BHT (ST), M3.0 ×6”
that fasten “FRAME, BOTTOM” and “SA,
MAIN FRAME”.
Detach the lower lugs and raise “FRAME, BOTTOM”.
Slide “FRAME, BOTTOM” upward to detach upper lugs
from “SA, MAIN FRAME”.
<Precaution at disassembly / reassembly>
When dismounting or mounting “FRAME, BOTTOM”, be careful not to damage the DC connector, DK
connector, and external device connector. When mounting “FRAME, BOTTOM”, align the lugs with four
slots, at which “FRAME, BOTTOM” is to be secured, slide it downward to engage the lugs, and fasten it with
screws.
Be careful not to allow connectors to interfere with each other in order to prevent deformation.
SCREW, BHT (ST), M3.0 ×6
Lugs
Lugs
Four slots
Slide upward.
DC connector
DK connector External device
connector
Lugs
Slide
downward.

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.
11. Disassembling “UNIT, MAIN PCB”
Remove four “SCREW, BHT (ST), M3.0 ×6”
that fasten “UNIT, MAIN PCB” and “SA, MAIN
FRAME”.
Remove one “SCREW, BHT (ST), M3.0 ×6” that
fastens “COVER, CABLE PROTECT-02” at the right
side, and disconnect the connector of “COVER OPEN
SENSOR”.
Disconnect the connectors of “SA, HEAD
CABLE-02” and “SA, PNE SENSOR” at the
left side.
Disconnect the connector of “SA, POWER SW” at the
rear.
Disconnect the connectors of “SA, PE SENSOR” and “UNIT, MOTOR” at the front, and remove “UNIT, MAIN
PCB”.
<Precaution at reassembly>
Connectors are provided at the right, left, and front sides. Be careful not to pull these cables by force.
When reassembling, be careful not to miss or catch any part, such as “FRAME”. Before disassembling
record the cable routing. When reassembling, reconnect the cables correctly. Pass “CABLE” of “COVER
OPEN SENSOR” through the hole on “COVER, CABLE PROTECT-02” and secure it.
SCREW, BHT (ST), M3.0 ×6
SCREW, BHT (ST), M3.0 ×6
COVER, CABLE PROTECT-02
J10: COVER OPEN SENSOR
Pass “COVER OPEN
SENSOR” through this hole.
J2: SA, HEAD CABLE-02
J5: SA, PNE SENSOR
J12: SA, POWER SW
J11: SA, PE SENSOR
J4: UNIT, MOTOR

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1-2-2. Disassembling “UNIT, MECHANISM”
1. Disassembling “SA, COVER OPEN SENOR - F”
Remove two “SCREW, No. 0 PHT (BT#3), M1.7 ×7” that fasten “SA, MAIN FRAME” and “SA, COVER
OPEN SENSOR” (2 pcs), as well as the tape that secures “CABLE”.
<Precaution at reassembly>
When reassembling, align the “SA, COVER OPEN
SENSOR” switch with the hole at “FRAME, MAIN”, and
secure it with one screw.
Do not forget to attach a tape to secure the cable.
2. Disassembling “GEAR DAMPER”
Remove two “SCREW, BHT (ST), M2.0 ×4” that fasten “SA, MAIN FRAME” and “GEAR, DAMPER”.
<Precaution at disassembly / reassembly>
The unit can be mounted in either orientation.
This part is not compatible with the one for CT-S801.
3. Disassembling “GEAR REDUCTION”
Remove “SCREW, PHT (#2), M3.0 ×8” and “SCREW, PHT (ST), M3.0 ×6” that fasten “SA, MAIN
FRAME” and “COVER, GEAR-02”, and remove “GEAR REDUCTION” from “COVER, GEAR-02”.
<Precaution at disassembly /
reassembly>
If the screws are tightened
excessively when reassembling,
“COVER, GEAR” will be damaged.
Be careful not to tighten them
excessively.
SCREW, No. 0 PHT (BT#3), M1.7 ×7
SCREW, BHT (ST), M2.0 ×4
SCREW, PHT (ST), M3.0 ×6
SCREW, PHT (#2), M3.0 ×8 GEAR REDUCTION
COVER, GEAR-02

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4. Disassembling “UNIT, PNE-02”
Remove two “SCREW, PHT (#2), M3.0 ×8” that fasten “SA, MAIN FRAME” and “PLATE, PNE
SENSOR-02”, and remove “SA, HEAD CABLE-F” from the hook. Remove “PLATE, PNE
SENSOR-02”, and then remove “UNIT, PNE -02”.
<Precaution at disassembly / reassembly>
Align two holes at “PLATE, PNE SENSOR-02” with the bosses at “SA, MAIN FRAME” and secure them with
screws.
5. Disassembling “SA, PAPER HOLDER-02”
Remove four “SCREW, BHT (BT), M3.0 ×6” that fasten “SA, MAIN FRAME” and “SA, PAPER
HOLDER-02”.
<Precaution at disassembly / reassembly>
Remove one screw from the left rear and three screws from the right.
SCREW, PHT (#2), M3.0 ×8
BOSS
Hooks
SA, HEAD CABLE-F UNIT, PNE-02
PLATE, PNE SENSOR-02
SCREW, BHT (BT), M3.0 ×6
Left side Right side
Right side

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Raise the rear of “SA, PAPER HOLDER-02” while pulling “GEAR, COVER DAMPER” outwardly, and
detach the bosses from the slot at “SA, MAIN FRAME”.
When removing “SA, PAPER HOLDER-02”, pull it upward while keeping it clear of the bosses at “SA,
MAIN FRAME” and the bent section at the front.
<Precaution at reassembly>
When reassembling, align the bosses at “SA, PAPER HOLDER-02” with the slot at “SA, MAIN FRAME”.
SA, PAPER HOLDER-02
GEAR, COVER DAMPER
Keep clear of these four
sections.

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6. Disassembling “SA, PE SENSOR”
Remove two “SCREW, PHT (BT), M2.0 ×6” that fasten “SA, PAPER HOLDER-02” and “SA, PE
SENSOR”.
7. Disassembling “SA, FRAME COVER UNIT-02”
Remove “WASHER, PLATEN” that fastens the hinged section at “SA, FRAME MAIN” to “SA, FRAME,
COVER” and “GEAR, COVER DAMPER”, and remove “GEAR, COVER DAMPER”.
<Precaution at reassembly>
When reassembling, align “GEAR, COVER DAMPER” with the shaft at “FRAME, MAIN” and the boss at
“FRAME, COVER”.
SCREW, PHT (BT), M2.0 ×4
SA, PE SENSOR
WASHER, PLATEN
GEAR, COVER DAMPER

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Remove “WASHER, PLATEN” from the “COVER, CABLE-02” side, and remove “SA, FRAME COVER
UNIT-02” from the hinged section at “SA, MAIN FRAME”. When removing “SA, FRAME COVER
UNIT-02”, make sure that “SA, FRAME COVER UNIT-02” is opened and that no load is applied to
“SPRING, COVEROPEN-02”.
<Precaution at disassembly / reassembly>
When reassembling, check the orientation of “SPRING, COVEROPEN-02”. Attach the bent side to the hook
at the “SA, MAIN FRAME” side, and attach the other side to the hook at the “SA, FRAME COVER UNIT-02”
side.
8. Disassembling “COVER, CABLE-02”
Remove “SCREW, PHT (ST), M2.0 ×4” that fastens “SA, FRAME COVER UNIT-02” and “COVER,
CABLE-02”, and slide “COVER, CABLE-02” sideways to detach the hooks. Then pull out “COVER,
CABLE-02”.
WASHER, PLATEN
SPRING, COVEROPEN-02
With bend
SCREW, PHT (ST), M2.0 ×4
COVER CABLE-02