Brother BAS-304A User manual

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SERVICE MANUAL
{ELECTRICAL)
FOR
BAS-300A SERIES
BAS-304A•311A•314A•315A .. /- ·--- =
326A•326LA•341A•342A
' .. ,·.. . ..
,
From the library of: Superior Sewing Machine & Supply LLC

This service manual has been compiled so that it
can bemadeintoa book sinceelectrical descriptions
for the BAS-300Aseries are verysimilar.
Applicable models are BAS-304A, 311A, 314A,
315A,326A, 326LA,341A,
and 342A.
For some of them, the electrical description is
separated for the air and solenoidspecifications.
From the library of: Superior Sewing Machine & Supply LLC

(ELECTRICAL CHECKAND DIP SWITCH)
Warning
Nevertouchthree large-sized capacitors onthe powercircuit board (see the illustration below). The high-
voltageresidual chargesstay for a minimum of 1-2 minutesafterthepoweristurnedoff.
Cautions
* Duringchecking or repair work whenthepower is applied,take care not to short-circuitterminals.
* Check ifthecooling fan in the control boxworkscorrectly. If it stops. electronic partsand devices maybe
damaged due
to high temperature inside the control box. To prevent the airvents from being choked
with dust,clean them at regular intervals.
II1 Fuses
Fuse4
Fuse3
Fuse2 -+-Bh
Fuse1
NOTE: When replactng the fuses, be sure to use the specified ones listed below.
No. Partname Partcode Manufacturer Problem
1 Fuse2A
152566-000
Fuji Tansi Company
The work clamp does not
(Glasstube fuse, 2A-125V)
FUJI 2A operate.
2
Fuse SA
152565-000
Fuji Tansi Company
Thepowerlamp does not come
(Glasstube fuse, SA·12SV) FUJI SA on and nooperation occurs.
3
Fuse 15A
502887·000
Fuji Tansi Company
The feed plate and presser
(Glass tube fuse, 15A-125V)
FUJI 15A
plate do notoperate.
4
GfuseSAFB
508030-000
Toyo Fuse Company The machine motor does not
(Quick melting type, SA-2SOV)
TOYOSA tum.
NOTE: Prior to replacing fuse No.4. be sure to check the TR array assembly.
Measure the resistance between the EB and e
terminals.
-1-
-If 20 - 30 n: Replace fuse 1. The TR array assembly
workscorrectly. (by 1 oon range)
- If 0 Q or co: Replace the TR array assembly andthe
pulse motordrive (PMD) PCB, instead of fuse 1.
From the library of: Superior Sewing Machine & Supply LLC

rzl Voltage measurement
1. Checkng the control voltage
ru·m on power while connecting the connector P8 to the control PCB, then measure the voltages
between pins1 and 2, 3 and 4,and between 5and 6 of connectorP1.
Check pointsof P8
on the control PCB
Acceptable value
Between pins 1 and 2 Approx.
65 Vdc
Between pins 3 and 4 Approx.
11 Vdc
Between pins 5and6 Approx.
25 Vdc
2. Checkng the + SV source
Turn
on power while connecting the connector P7 to the control PCB, then measure the voltage between
pins 1and 2 of connectorP7.
3. Checkng solenoids' voltages
P1
1
Check points of P7
on the control PCB
Between pins 1and 2
Acceptablevalue
Approx.
65 Vdc
(1) Turn off the power.
Remove P1 from J1, and measure each solenoid's
resistance.
Resistance values are different according to the
sewingmachinemodel.
Check points Solenoid Value 304A 326A 341A
311A 326LA 342A
Between Intermittent
Resistance 50
12n
~
pins1 and2 presserfoot Voltage
12V
20V
_/"
Proslerfoot(Oftly
Resistance 50
./'
~
forsolennl
./'
~ Between tpedfb11oct) Voltage 10V
pins3and4
Tension
Resistance
:;?'
50 _/"
release
Voltage
~
20V
~
Between
Thread
Resistance
50 sn
100
pins5and6 trimmer Voftege
30V
20V · 60V
Between Thread
Resistance
60
110
60
pins7and8 wiper Voltage 30V
20V 30V
)&( Resistanceandvoltagevalues are approximate.
(2) lnsertP1 intoJ1,andturnonthe power.
·2-
Insert
the test probe from the lead wire side, and
measurethevoltage.
• As for the presser foot and intermittent presser
foot solenoids, measure the voltage while raising
and lowering them.
·As for tension release, thread trimmer, and
thread wiper solenoids, start sewing, then
measure the voltageuponfinishing of sewing.
Since,
in this case, the indicator only oscillates
very briefly, the value is used as a rough
measure.
Each voltagevalueis as in the above table.
... _.,.,.
From the library of: Superior Sewing Machine & Supply LLC

4. Checkng air valve's voltage
NOTE: When the machine is for solenoid specification of the BAS-304A or 311A, there is no need to
connectthe air valves.
(J) Presser foot (R) valve
e Presser foot (L)valve
G Intermittentpresservalve
(only for BAS-341A and 342A)
® Innerclampvalve
$ Optionvalve 1
8 Optionvalve2
(/) Optionvalve3
8 Needle coolervalve
~ +24V
® +24V
NOTE: @to 8 areoptions.
1) Turn the power switch OFF. Disconnect connector
P8 from J8, then measure the resistance of each
valve.
Resistance of each valve (from (t) to$, e to~)
should be approx.3000.
2) Connect connector P8 to J8, then turn the power
switch ON.
Insert the test probes into connector P8 from the
lead
wire side, then measure the voltages.
Check points Acceptable value
Between pins 1 (-}and 10C +)
0.1V-24V
Between pins2 (-)and 10C +)
0.1V-24V
Between pins3 (-}and 10( +) 0.1V-24V
When the work clamp pedal is treadled, each
readingshould be max. 24VI min. 0.1V.
3) When the optionalvalve Is used:
-3-
Measure the resistance between each valve and
®. (Refer to step1.)
Measure the resistance between each valve (-)
and ® ( +) when each valve operates. (Refer to
step2.)
From the library of: Superior Sewing Machine & Supply LLC

Ill Control box
J6
fi~---~
"---- •.
_____ ,
J1 Solenoid connector
J2 Synchronizerconnector
J3 Connectorfor emergencystop, zero-point
sygnal and thread breakage detection
J4 X-drive pulse motor connector
JS Y-drive pulse motor connector
J& Footswitchconnector
J7 Programmingdeviceconnector
J8 Air valveconnector
J9 Machinelightconnector(6VAC. 2A)
J10 : Marker light connector (SV AC, 3A)
J1
J2
~0
JS J4
~~
r---.,
lra:QJI
: 1 s1o
~Kmlr
'"---.J
lool
J9
0
J8
From the library of: Superior Sewing Machine & Supply LLC

Ill Explanation of connectors
If the machine has been disassembled or adjusted during repairwork, most of the machine troubles are due
to connector problems including improperconnection or weakcontact. It is, therefore, necessary to check
each connector numberand pin contact
for correct connection prior to proceeding to thetroubleshooting
procedures.
The table below lists the connectornumbersand symptoms resulting from wrong connections. For detailed
connectorand harnessarrangement, refer to •coNTROL CIRCUIT BLOCK DIAGRAM•.
Connector No. and location
Main PCB
I P8 I
I P3 I
PMDPCB
I .MainPCB I
I P6 I I PS I
m [5[5
ElBg
I J11 I
Solenoid Air valve
~In~
~~
PS
Y nlsve.
pu a
motor
I
Motor ll Main PCB I
-[ L ·I P13 LJ
;. I: :I I:
1: :~M+r: :1
I I I 1 I
I
PMD
I
I I
Main PCB
I P14 I
~
I P2 I
r.
Synchronizer l
Drivesignalsand source
Control power source
Solenoiddrivepower source
Pulse motor drive power
source
Symptoms resulting from wrong connection
• Abnormal motion
• Nomotion
• OnlyPan motor operates
• Faulty
operation of the presser plate,
presser foot, thread wiper components,
main presser, thread trimming , thread
releasecomponents
• Stepout in Xand Y axes
• Unusual noises of X-drive andY-drive pulse
motors
Start/stopcontrol currents
for • Abnormal rotationspeed of the pulley
the machine
+SV
Needlestopposition control,
synchronizationcontrol,and
rotationcontrol signals
.. s-
• Stopoperationfailure
• The pulley does not rotate
• The
machine sews at abnormally high
speed, then stops. (The EMERGENCY stop
lamp lights.)
• The machine does not stop with the needle
at the upperposition.
• The pulley rotates, but the feed mechanism
does not work .
From the library of: Superior Sewing Machine & Supply LLC

ConnectorNo. and location
Main PCB
[PO
f I P1 l J
1control panel PCBJ
Main PCB
em]
·I Programmer ~
I
MainPCB .J
IIP31 P7 II
86
I Floppy disk I
Main PCB
Qifl
~
~
r ,,2 1
T T
Xh I . . h I
..
ome position Y ome positiOn
I PCB PCB i
Main PCB
QCJ
Drive signals and source
+SV
Speed control signal
Key andswitch signals
Indicatorcontrol sig~ls
Read and write signals
from/to floppy disks
X
andY home position
signals
EM switchsignal
LED signal
Drivesignal
Presser plate lifting signal
Symptoms resultingfrom
wrong connection
• The POWER lamp does not comeon.
• Although the speed <ontrol dial is turned,
the machine does riot change the rotation
speed and keeps it at 2000 spm.
• Malfunction of programming device
• The floppy diskdata cannot be read.
(ErrorNo.4)
• Themachine cannot detect home position.
• The emergency stop function cannot be
activated.
• The EMERGENCY stop lamp lights and its
function cannot becanceled.
• The machine neither starts operation nor
lifts the presser plate If the corresponding
foot switch is depressed.
From the library of: Superior Sewing Machine & Supply LLC

liJ Dip switch settings
NOTE: Be sure to turn off the power before changing the DIP switch settings.
ct::::J.
0
®
No.
When ON
1 Workclamp
does not rise whensewing com plated
2 Rfght..,.lefttwo-stepworkclamp(When
No.4 fs ON)
3
Left~ righttwo-stepworkclamp(WhenNo. 41s ON)
Fer the BAS-304A or 311A
with solenoid spedfication,
4 Whenthe
switches 2,3and4 areon. left and rightwork clamps will descend
set® No.2~ 3# and 4 to OFF.
at onetimerand presserfoot will descend With two positions.
5 Workclampdoes
not rise during split mode operation.
6
Presser crank of Innerclamping device turns to theother side
(Innerdamping device Is optional.)
7 Single pedaloperation
possible using thest.rtingpedal
8 Activatesthread breakagedetector
(Thread breakagedetector Is optional.)
No. WhenON
1 Singlesplit
mode possible
2 8000-stitch sewing mode
possible
3 Threadtrimming does notfunctionwhen emergency stopswitd1 is pressed.
4 Needlecooler
can be used.(Needlecooler device Is optional.)
5 Thread breakagedetectionstitch marginsetting
can be set to either8 or 14 stitches.
6 Ad:ivatesfiberthread breakagedetector(optional part)
7 Tripletpedal operation
possible {Triplet pedal is optional.}
8
High feed speed
©
No. When ON
, Thefirsttwostitchesare
sewn at low speed (approx. 260 spm).
2 Thelalttwo stitchesare sewn at low speed (approx. 260 spm).
3
The upparshaftturns In the reverse directionafterttveadbreakage, andthe machine stops
with the needle at its highestposition.
4 Does
not output error No.2even If synchronizer Is notconnocted
-7-
From the library of: Superior Sewing Machine & Supply LLC

@ The setting of the DIP switch@ in the control boxdetermines the machine model.
* If thesetting is not correct for the machinehead, It may cause damage to a printedcircuit board.
0-1
304A
OFF
311A ON
326A
OFF
326LA ON
341A OFF
342A ON
No.
1
2
3
4
5
6
7
8
9
A
D-2
OFF
OFF
ON
ON
OFF
D-3
OFF
OFF
OFF
OFF
ON
No.2 0N
No.1, 3,4 OFF
D-4
OFF
OFF
OFF
OFF
OFF
No.1,20N
No.3,40FF
( ERROR NO. LIST)
Cause
Emergency stopswitch pressed
Trouble with themotor or synchronizerI Motor stopped whenvoltagedropped
Over-area
Floppydisk
not inserted, or cable not properlyconnected
Floppydisk
is locked (writeprotected)
Noprogramregistered
Erroroccurred in program mode
Thread breakagedetected
Protection networkactivated
because of abnormal voltage
No usable pattemdataon di'k ·
From the library of: Superior Sewing Machine & Supply LLC