JUKI HZL-UX8 User manual

SERVICE MANUAL
HZL-UX8 Series
COMPUTER SEWING MACHINE

Be sure to observe the following to protect against a re, electrical shock, injury or damaged components.
* Be sure to unplug the machine before disassembly, assembly or adjustment of the machine.
* Be sure to carefully prevent electric cords from being caught, coated surfaces from being damaged
as well as wrong wiring during assembly.
* Be sure to use the proper genuine parts when changing any of the machine parts.
CAUTION:
CONTENTS
[1] Specications of HZL-UX8 ........................................................................................ 1
[2] Search by trouble (related to mechanical components) ........................................ 3
[3] Principal parts ............................................................................................................ 4
[4] Disassembling the machine covers ......................................................................... 5
[5] PCB connection diagram ........................................................................................ 12
[6] Adjustment ............................................................................................................... 16
6-1 Adjusting the needle bar height ...................................................................... 16
6-2 Adjusting the needle entry point ..................................................................... 17
6-3 Feed dog height ................................................................................................ 18
6-4 Timing belt ........................................................................................................ 19
6-5 Feed timing ....................................................................................................... 19
6-6 Adjusting the shield ......................................................................................... 20
6-7 Hook driving shaft coupling and the lateral timing of the hook driving shaft .. 21
6-8 Timing between the needle and the hook ...................................................... 22
6-9 Clearance between the needle and the blade point of hook ........................ 23
6-10 Position of the hook rotation stopper plate ................................................. 25
6-11 Adjusting the bobbin thread tension ............................................................ 25
6-12 Adjusting the needle thread tension ............................................................. 26
6-13 Vertical position of the needle threading hook ............................................ 27
6-14 Adjusting the auxiliary hook height .............................................................. 28
6-15 Adjusting the opening amount of auxiliary hook ........................................ 29
6-16 Adjusting the presser bar height .................................................................. 29
6-17 Motor belt ........................................................................................................ 30
6-18 Longitudinal feed ............................................................................................ 31
6-19 Presser foot lifting .......................................................................................... 32
6-19-1 Position of the presser foot lifting motor ....................................................32
6-19-2 Adjusting the height of the auto-lifter ..........................................................33
6-20 Thread trimming ............................................................................................. 34
6-20-1 Attaching/removing the thread trimmer unit ...............................................34
6-20-2 Adjusting the thread trimming switch .........................................................35
6-21 Attaching/removing the top feed dog ........................................................... 36
6-22 Position of the automatic DF motor .............................................................. 37
6-23 Bobbin thread detection sensor ................................................................... 38
6-23-1 Attaching/removing the bobbin thread detection sensor ..........................38
6-23-2 Adjusting the bobbin thread detection sensor ...........................................39
6-24 Service mode .................................................................................................. 40
6-24-1 Service mode screen .....................................................................................40
6-24-2 Service-mode items and descriptions .........................................................40

– 1 –
(1) Power switch
• 220-240V AC common to 50/60 Hz
• 120V AC common to 60 Hz
(2) Power consumption
• 90 W
(3) Dimensions and weight
• Dimensions Main unit: 602 (width) × 264 (depth) × 310 (height) (mm)
• Weight Main unit: 14.9 kg
(4) Revolution control
• Slide style speed control
Straight stitch 80 to 1,050 sti/min (SPM)
Pattern stitch 80 to 750 sti/min (SPM)
Reverse stitch 80 to 1,050 sti/min (SPM)
 (Sewingspeedotherthanthespeciedrangecanbesetoptionally.)
80 to 1,050 sti/min (SPM) (when the speed controller is used.)
Bobbinwinding 1,500to3,000sti/min(SPM)
Low-speed start 80 to 110 sti/min (SPM) (approx. 1 second only when the power switch is turned ON.)
• Foot controller
Evenwhenthefootcontrollerisused,thespeedcontrolfunctionbymeansofthesliderise󰀨ective.
Tostopthemachine,eitherreleasethefootcontrollerorpressstart/stopbutton.
Thenumberofrevolutionsiscontrolledinthewaysamewiththecaseoftheslidespeedcontrol.
Toe-uppedalingfunctioncanbesetoptionally.
• Safety control
When the motor shaft of the sewing machine is accidentally constrained, the power supply to the motor is
stopped within two seconds.
Whenthemotorisoverheated,thebuiltinthermalswitchstopsthepowertothemotor.
Notethatthemachinecanberestartedoncethemotorspontaneouslycoolsdown.
(5) Stop position
•Uponnishingsewing,themachinestopsaccordingtothepresetneedlestopposition(withitsneedleupor
down).
•Uponnishingreversestitching,themachinestopswithitsneedledown.
• Needle moves down when the machine has preset so that the needle stops at its up position and needle up/
downbuttonispressed.
• Needle moves up when the machine has preset so that the needle stops at its down position and needle up/
downbuttonispressed.
• In the case of fault, the machine stops immediately (stop position varies).
(6) Zigzag width
• Max. 7 mm depending on the pattern selected
(7) Amount of feed
•Theamountoffeedischangedinincrementsof0.2mmbythestitchlengthadjustingdial(orbutton).
 (Fortheparallelpartsofabuttonholeandsatinstitches,theamountfeedischangedinincrementsof0.1mm.)
Default setting: 2.4 mm (for straight stitching)
[1] Specications of HZL-UX8

– 2 –
(8) Pattern selection
• Selection is made on the touch panel
(9) Number of patterns that can be selected
• Max. 70 patterns
(10) Number of patterns
• 368
(11) Automatic threading device
•Thehooksectionmakesaturnbyloweringthethreadinglever,andautomaticallyreturnstoitsoriginalposition
after completion of threading.
(12) Automatic lock stitch
WhenthebacktackingswitchisturnedON:
• Straight stitch: Three stitches are sewn in normal direction and three stitches are sewn in reverse direction at
thebeginningandend(thereverseswitchisturnedON)ofsewing.
Amount of feed: Same with the preset amount of feed
• Other patterns: Zero-feed is inserted and one each stitch is sewn in the normal and reverse directions at the
beginningandend(thereverseswitchisturnedON)ofsewing.
Amount of feed: Fixed at 0.4 mm
(13) Buttonholing
Auto-returntypefullautomaticbuttonholing
Buttonholing size detection
(14) Save and call patterns
Selectedpatternsandpatternsettingscanbestoredinmemory.
Inaddition,thepatterncanbecalledupfrommemoryforsewing.
Numberofpatternsthatcanbestoredinmemory:10(folders)
(15) Helpful messages
• Presser foot lifting lever
• Buttonholing foot
• Display of pattern storage limitation
• Pattern clear prompt
• Memory storage
• Acceptance of setting change
• 2-needle setting
• Motor lock
• Straight stitch selection
•Throatplatehascomeo󰀨
• Top feed

– 3 –
[2] Search by trouble (related to mechanical components)
Phenomenon Itemtobechecked
Faulty thread tension 6-10: Position of the hook rotation stopper plate
6-11:Adjustingthebobbinthreadtension
6-12:Adjustingtheneedlethreadtension
Stitch skipping 6-1:Adjustingtheneedlebarheight
6-2:Adjustingtheneedleentrypoint
6-5: Feed timing
6-8:Timingbetweentheneedleandthehook
6-9:Clearancebetweentheneedleandthebladepointofhook
Threadbreakage 6-1:Adjustingtheneedlebarheight
6-8:Timingbetweentheneedleandthehook
6-10: Position of the hook rotation stopper plate
Hitch stitch 6-2:Adjustingtheneedleentrypoint
Faulty material feed 6-3: Feed dog height
6-16:Adjustingthepresserbarheight
6-22: Position of the automatic DF motor
Contactbetweenneedleandthroatplate
or hook
6-2:Adjustingtheneedleentrypoint
6-5: Feed timing
6-8:Timingbetweentheneedleandthehook
Faulty pattern shape 6-3: Feed dog height
6-18: Longitudinal feed
Faulty automatic thread trimming 6-6:Adjustingtheshield
6-20-1: Attaching/removing the thread trimmer unit
6-20-2:Adjustingthethreadtrimmingswitch
Faulty operating noise 6-4:Timingbelt
6-17:Motorbelt
Needle threader 6-13: Vertical position of the needle threading hook
Fails to start sewing 6-19-2:Adjustingtheheightoftheauto-lifter
Faulty automatic presser foot lifting height 6-19-2:Adjustingtheheightoftheauto-lifter

– 4 –
[3] Principal parts
Spool cap (large)
Spool pin
Operation panel
Face plate cover
Threading lever
Start/stopbutton
Presser foot lifting lever
Needle setscrew
Needle
Presser foot
Sensorpinholeforbuttonholing
Presserfootreleasingbutton
Feed dog
Throat plate
Hook cover
Bobbinwinding
shaft
Hookcoverreleasebut-
ton
Presser foot holder
Threadtrimmingbutton
Auxiliarybed
(accessory case)
Thread cutter
Lockstitchbutton
Speed controller
Needleup/downbutton
Knee lifting lever
hole
Light under arm
Reverse stitch
button
Feed dog UP/DOWN /
LOCKMODEbutton
Hand wheel (pulley)
Power switch
Machine-socket-inlet
Foot-controller-jack
USB insertion slot
“JUKI Smart Feed”
Presser foot holder setscrew
Presserfootautoliftbutton
Handle

– 5 –
❶❶❷❷
○Toremovethetopcover,bowthehingesectionoftherightsideofthecover.
○Remove setscrews ❶and ❷from the face cover.
Then, remove the face cover.
○Fittingaat-bladescrewdriver(T-shape)inthenearestslotinthethroatplate,
pushupthethroatplatewiththescrewdriveruntilitcomeso󰀨.
Then remove the throat plate.
[4] Disassembling the machine covers
1) Top cover
2) Face cover
3) Throat plate
T-shape

– 6 –
Base tension
❺❺❻❻
❼❼
❽❽
❸❸
❹❹
❾❾
󱢳󱢳
Junction connector
○Remove setscrews ❸and ❹from the thread tension cover.
Remove the thread tension cover.
○Remove setscrews ❺to 󱢳from the spool cover.
○Removethebobbinwindingmotorjunctioncablefromthejunctionconnector.
○Remove the spool cover from the main unit of the machine, paying attention to
thebasetension.
4) Spool cover

– 7 –
󱢸󱢸
󱢹󱢹
󱢺󱢺
󱢻󱢻
󱢼󱢼
󱢽󱢽
󱣀󱣀
󱢿󱢿󱣁󱣁
󱢾󱢾
○Remove setscrews 󱢸to 󱢽ofthebottomcoverB(onthehandwheelside)to
detachthebottomcoverB.
○Remove setscrews 󱢾to 󱣁ofthebottomcoverA(ontheframeside).Draw
outthebottomcoverAinthedirectionofthearrowwhilepushingupthetipof
the cover.
6) Bottom cover
○Removebeltcoversetscrews󱢴to 󱢷.
○Push portion Bto disengage portion A.
○DetachthebeltcoverwhilecarefullycheckingthesupportofportionC.
5) Belt cover
A
B
C
󱢵󱢵
󱢴󱢴
󱢶󱢶
󱢷󱢷

– 8 –
○Removefree-armlowerbottomcoversetscrews󱣂and 󱣃.Pulloutthebot-
tom cover of the free arm in the direction of the arrow.
7) Bottom cover of the
free arm
8) Upper cover of the
free arm
󱣂󱣂
󱣃󱣃
󱣆󱣆
󱣄󱣄󱣅󱣅
○Remove free-arm upper cover setscrews 󱣄and 󱣅. Remove setscrew 󱣆,
the collar and the washer, and pull out the free-arm upper cover in the direc-
tion of the arrow.
Collar
Washer

– 9 –
󱣇󱣇
󱣈󱣈
9) Face plate cover ○Remove setscrews 󱣇and 󱣈from the face plate cover.
Remove the face plate cover.

– 10 –
10) Front panel ○Remove setscrews 󱣉to 󱣋from the front panel.
○Put a thin screwdriver in the notch (Dsection) in the rising section under the
armandpryo󰀨thefrontpanelandhook(Esection) of the rear panel.
○Put the thin screwdriver in the notch (Fsection)inthejawsectionandpryo󰀨
the front panel and the hook (Gsection) of the rear panel.
○If needed, detach the connectors (CN17 and CN18) of the switch / slide VR,
the connector (CN19) of the panel I/F, and the connectors (CN35, CN36 and
CN37)oftheLEDfromthemainPCB,andalsodetachthejunctionconnector.
󱣉󱣉
󱣊󱣊󱣋󱣋
D
F
E
G

– 11 –
11) Rear panel ○Remove setscrews 󱣌to 󱣐from the rear panel.
Remove the rear panel with the presser foot lifting lever raised.
Main PCB
Panel I/F (CN19)
SW/slide volume
PCB (CN17)
Junction connector
SW/slide volume PCB
(CN18)
LED connector, green (CN35)
LED connector, white (CN36)
LED connector, white (CN37)
󱣏󱣏
󱣌󱣌󱣍󱣍
󱣐󱣐
󱣎󱣎

– 12 –
[5] PCB connection diagram
• Main PCB Connec-
tor No. Destination Termi- nal No.
CN13 Presser-lifter
STM
1A
4.0Ω
2 A
3 B
4.0Ω
4B
CN14 Top feed STM 1 A
4.0Ω
2 A
3 B
4.0Ω
4B
CN15 Thread tension
STM
1A
4.0Ω
2 A
3 B
4.0Ω
4B
5 GND
6 Origin detection signal
7 5V
CN16 BH sensor 1 GND
2 BHR switch
3 BHS switch
4 3.3V
CN17 SW/slide vol-
ume PCB
1 LED G
2 LED R
3 Reverse stitch switch
4 S/S switch
5Thread trimming switch
6Needle up/down switch
7 Auto-lifter switch
8 Lock stitch switch
9 GND
10 Speedcontrolvariable
resistor
11 GND
12 5V
CN18 SW/slide vol-
ume PCB
1 DF switch
2 LED DF
3 GND
CN19 Isolate PCB 1 5V
2 5V
3 GND
4 GND
5 RXD
6 TXD
7 S.STATE
8 UDET
9 Reset
10 5V
11 5V
12 Panel detection signal
13 GND
14 GND
15 NC
Connec-
tor No. Destination Termi- nal No.
CN1 Debug
(Unused)
1 3.3V
6 GND
CN2 Flash memory
interface
1 5V
5 GND
CN3 Needle throwing
STM
1A5.0Ω
2 A
3 B 5.0Ω
4B
CN4 Feed STM 1 A4.0Ω
2 A
3 B 4.0Ω
4B
CN5 Thread trimming
STM
1A4.0Ω
2 A
3 B 4.0Ω
4B
5 GND
6 Origin detection signal
CN6 Potentiometer
cableasm.
1 3.3V
2 Position detection
signal
3 GND
CN9 Throat plate
switch PCB
1 Throat plate switch 1
2 Throat plate switch 2
3 GND
CN4
CN14
CN5
CN20
CN13
CN15
CN3
CN31
CN6
CN17
CN29
CN25
CN30
CN39
CN40
CN26 CN16 CN2 CN18 CN34 CN1
CN28
CN27
CN19
CN9
CN35
CN36
CN37
CN38

– 13 –
• Power PCB
Connector No. Destination Check
CN1 Power SW AC input
CN2 Power supply relay lead wire 1-2PIN 29V, 4-5PIN GND (FG)
CN1
CN2
Connec-
tor No. Destination Termi- nal No.
CN20 Automatic DF
STM
1A
4.0Ω
2 A
3 B
4.0Ω
4B
CN25 Main shaft de-
tection PCB
1 5V
2 Motor pulse
3 S1
4 S2
5 S3
6 GND
CN26 Bobbinwinding
motor
1Bobbinwinderswitch
2 GND
3Bobbinwindermotor(+)(29V)
4Bobbinwindermotor(-)
CN27 Controller socket 1 GND
2 Controller
CN28 Power supply
relay lead wire
1 29V
2 29V
3 NC
4 GND
5 GND
CN29 MotorlterPCB 1Mainmotor(+)(29V)
2 Main motor (-)
3 FG
Connec-
tor No. Destination Termi- nal No.
CN30 Knee lifter slide
VR PCB
1 3.3V
2 Knee lifter position detec-
tion signal
3 GND
CN31 Presser foot lifting
switchcableasm.
1 Presser foot lifting switch
2 GND
CN34 Top feed detection
PCB
1 3.3V
2 Top feed detection signal
3 GND
CN35 LED PCB 1+5V
CN36 LED PCB 1+5V
CN37 LED PCB 1+5V
CN38 LED PCB 1+5V
CN39 Bobbinthread
detection sensor 1
1+5V
2 Sensor input signal
CN40 Bobbinthread
detection sensor 2
1 Infrared LED output
2 GND

– 14 –
• Panel PCB
Connec-
tor No. Destination Terminal No.
CN1 Panel PCB power
cableasm.
1+12V
2+12V
3 GND
4 GND
CN2 Speaker 1 +
2 -
CN5 Isolate PCB 1 GND
2 3.3V
3 TXD
4 RXD
5 S.STATE
CN6 Dial PCB 1 +3.3V
2 DIAL1_A
3 DIAL1_B
4 GND
CN9 LCD 1 to 3 Backlight(+)
4 NC
5 to 8 Backlight (-)
9 NC
10 to 36 LCD signal
37 NC
38 to 40 GND
Connec-
tor No. Destination Terminal No.
CN16 USB 1 5V
2 to 3 USB signal
4 GND
CN20 Touch panel 1 to 2 GND
3 to 8 Touch panel signal
9 to 10 GND
CN21 Dial PCB 1 NC
2 DIAL2_A
3 DIAL2_B
4 DIAL3_A
5 DIAL3_B
6 to 7 NC
8 to 10 GND
CN6 CN5 CN2 CN1
CN16
CN9
CN21 CN20
CN6 CN5 CN2 CN1
CN16
CN9
CN21 CN20
Top surface Back surface
• Compact power supply PCB
CN1
CN2
Connector No. Destination Check
CN1 Power SW AC input
CN2 PanelPCBpowercableasm. 1-2PIN 12V, 3-4PIN GND

– 15 –
• Connection block diagram
CN18
CN25
4P
6P
CN31
CN6
2P 3P
CN3
4P
CN15 CN13
7P 4P
CN20
4P
CN29
3P
CN9
CN19
3P
3P 15P
CN27 CN28
2P 5P
CN5
CN20
CN9 40P
Panel PCB
Main PCB
WHITE BLACK
RED
RED BLUE
BLACK
WHITE
10P
6P 4P 4P
CN1
4P
CN4
CN14
CN5
BLUE GREEN WHITE
CN17
CN16
CN1
GREEN
CN30
BLACK
12P
3P
15P
3P
CN38 CN37 CN36
CN35
3P 3P 3P 3P
CN1
CN2
CN1 CN2
Dial PCB
CN21
CN3 USB typeA
CN2
CN2
Speaker
10P
4P
USB typeA
CN39
2P
RED
CN40
2P
Isolate PCB
CN26 CN16 CN2
CN34
Power PCB
relay cable asm.
CN6 CN1
LCD
1280× 800
BLUE
Bobbin winding motor
Potentiometer cable asm.
Thread tension origin detection PCB
Needle throwing STM
Feed STM Main motor Motor filter
PCB
Top feed STM
Flash memory
interface
SW/slide volume PCB
Thread trimmer origin detection SW
Presser foot lifting switch cable asm.
Thread tension STM
Presser-lifter STM
Automatic DF STM
Thread trimming STM
Unused
BH sensor
Top feed detection PCB
Main shaft detection PCB
Controller socket Foot controller
Power SW Power cord
Power supply relay lead wire
Power PCB
Knee lifter slide VR PCB
Throat plate switch PCB
On hand LED PCB 1 On hand LED PCB 2
Under arm LED PCB 1 Under arm LED PCB 2
Bobbin thread detection sensor 1
Bobbin thread detection sensor 2
Compact power supply PCB
Wireless LAN antenna
Provided with a touch panel
Panel FG cable
USB cable

– 16 –
[6] Adjustment
6-1 Adjusting the needle bar height
○Remove the face cover.
Adjustmentvalue:
・
Distancefromthebottomendofthepininsideneedlebarsurfacetothetopsurfaceofthethroatplate:
19 mm
・
Whentheneedleismounted,theneedleeyetiltsrightwardby2degrees.
Adjustmentprocedure1.
 1.Selectthestraightstitchusingthepatternselectingbutton.Choosecenterneedleposition.
 2.MakeagaugeneedlebycuttingahouseholdneedleHA×1todimensionA.Fitthegaugeneedleintothe
needlebar.
3. Prepare an appropriate metal plate of thickness B. (A = 19 mm - B)
 4.Bringtheneedlebartoitslowestdeadpoint.Slightlyloosenneedlebarconnectingstudsetscrew❶as
longastheneedledoesnotslipo󰀨fromtheconnectingstud.
 5.Placethemetalplateonthethroatplate.Movetheneedlebarupanddownbyhandtoadjustsothatthe
cutsurfaceofthegaugeneedlealignswiththetopsurfaceofthemetalplate.Then,turntheneedlebarby
twodegreesofanangleasillustratedinthesketchbelow.
 6.Temporarilytightenneedlebarconnectingstudsetscrew❶andreconrmthattheneedlebariscorrectly
adjusted.Then,securelytightenthesetscrew.
Adjustmentprocedure2.
 1.AssembleahouseholdHA×1needle#14intotheneedlebar,bringtheneedlebartoitshighestdead
point.Movetheneedlebarinthesamewayasdescribedinprocedure1toadjusttheneedlebarheightso
that the needle tip is spaced 15.5 mm from the top surface of the throat plate.
19 mm
Metal plate
Throat plate
2°
[Lowest dead point]
A
B
Gauge needle
15.5 mm
[Highest dead point]
HA×1 #14
❶

– 17 –
6-2 Adjusting the needle entry point
○Remove the face cover.
Adjustmentprocedure
 1.Selectthestraightstitchusingthepatternselectingbutton.Choosecenterneedleposition.
 2.Assembleaneedle#14intotheneedlebar,loosenthesetscrewintheeccentriccollarandadjustthefeed
bareccentriccollarsothattheneedlemeetsthecenteroftheneedleslotinthethroatplatewhenitreach-
esthetopsurfaceofthethroatplatebyturningthehandwheel.
Setscrew
Feed bar eccentric collar

– 18 –
6-3 Feed dog height
○Removethethroatplate,thebottomcoverofthefreearmandtheuppercoverofthefreearm.
Adjustmentprocedure
1. Attach the throat plate after you have removed the cover. (Fig. 1)
2. Set the feed to "0" (zero).
 3.Turnthehandwheeltobringthefeeddogtoitshighestpoint.
 4.Adjustthefrontendofthefeeddogbyturningtheadjustmentshaft,withathinatbladescrewdriver,from
thetopsurfaceofthethroatplate.(Fig.2)Toadjusttherearendofthefeeddog,loosenthesetscrew,and
adjusttheheightofthefeeddog,withaatbladescrewdriverorthelike,byinsertingthescrewdriverinto
theadjustmenthole.Aftertheadjustment,tightenthesetscrew.(Fig.3)
 5.Adjustthefeeddogheightbothatitsfrontandrearendssothatitjutsoutfromthetopsurfaceofthe
throatplateby1.0±0.1mm.(Fig.4)
1.0 ± 0.1 mm 1.0 ± 0.1 mm
Adjustment shaft hole
Front end of feed dog
Read end of feed dog
Adjustment shaft
Setscrew
Flat blade
screwdriver
or the like
Fig.1 Fig.2
Fig.3
Fig.4
Adjustment
hole
Adjustment
hole
Feed dog height
decreases
Feed dog height
increases