JVC AV28CH1EUB, AV28CH1EUS Service Manual

B

SERVICE MANUAL

COLOUR TELEVISION

AV28CH1 EUS
AV28 CH1 EU

BASIC CHASSIS

AV28CH1EUS AV28CH1EUB

MF

CONTENTS

! SPECIFICATIONS ････････････････････････････････
!

SAFETY PRECAUTIONS

!

FEATURES････････････････････････････････

! MAIN DIFFERENCE LIST ････････････････････････････････
!

SPECIFIC SERVICE INSTRUCTIONS

! SERVICE ADJUSTMENTS ････････････････････････････････
!

PARTS LIST

★

STAND ARD CIRCUIT DIAGRAM

1

････････････････････････････････････････････････････････････････

････････････････････････････････････････････････････････････････

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････････････････････････････････････････････････････････････････

･･･････････････････････････････････

････････････････････････････････････････････････････････････････

･･･････････････････････････････････････････････････････

････････････････････････････････････････････････････････････････

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･････････････････････････････････････････････

････････････････････････････････････････････････････････････････

･････････････････････････････････････････････････････

････････････････････････････････････････････････････････････････

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････････････････････････････････････････････････････････････････

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････････････････････････････････････････････････

････････････････････････････････････････････････････････････････

COPYRIGHT © 2002 VICTOR COMPANY OF JAPAN, LTD.

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･･･ 5

･･････

･･･････････････････････ 5

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･････････････････････ 12

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31

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2- 1

4

6

No.519 44
Mar. 2002

A

V28CH1EUS

A

y

V28CH1EUB

SPECIFICATIONS

Item

Dimensions ( W××××H××××D ) 72 5mm×4 80m m×496mm
Mass 34 .7 kg

TV RF System

Colour Sy stem PA L / SECA M / NT SC (Only i n EXT mode)

Stere o Sy st em A2 (B /G,D/K)/ NICAM(B/G,I ,D/K,L)

Teletext System FLOF (Fastext)

Receiving Frequency

Interme diate Fr equenc

VIF Carrier 38 .9 MHz ( B/G , I ,L)/ 3 3.9 5 MHz (L’)

SIF Carrier 33 .4 MHz ( 5.5MHz :B/ G) / 32.9MHz (6.0 MHz:I ) / 32.4MHz (6.5MHz:L , D/K) / 40 .45MHz (6.5MHz:L’ )

Colour Sub Carrier Fr eq.

SE CAM 4.40625MHz/4.25MHz

Power Input AC 2 30V , 50Hz
Power Consumpti on

CCIR (B/G,D/K, I ,L, L ’)

TOP (German syst em)
WST(W orld Standard system)

VHF 47 MHz ～ 47 0MHz

UHF

470MHz ～ 8 62MHz

PAL 4.43MHz

NT S C 3.58MHz / 4.43MHz

16 5W ( Max) / 112W(Avg) , sta ndby : 2.8W

AV28CH1EUS / AV28CH1EUB

Content

Aerial Input Term

Pictur e Tube

Hi gh Vo lt ag e

Speake r

Au dio Output 5W + 5W

EX T-1 /EXT-2/EXT- 3
(Input / Output)

S / Video

EXT-4 (Input) Video

Au di o (L /R )

S / Video

AUDIO OUT (Vari able)

Headphone jack St ereo mi n i jac k (φ3.5mm )

Remote Control Unit RM-C 54 H (AAA/R 0 3 dr y batte ry×2) : (A V2 8CH1EUS) / R M-C50( AAA/R03 d r y bat tery×2 ) : (A V2 8CH1EUB)

75 Ωun ba l anc ed, C oaxi al

Visi ble si ze : 66 cm, Meas ured di a gon al l y

1kV

+

30.0kV (at zero beam current)

-1. 5kV

(10c m×3cm) ov al typ e ×2

21 -pin E ur o c onnec to r
(SCART socket)

p-p

Y : 1V

C : 0.3V

1V p- p 7 5Ω(RCA pi n jack)

50 0mVr ms( -4dB s ), H igh Impe dan ce ( RCA pin jack )

Y : 1V

C : 0.3V

0～1 Vrms, Low Imp ed ance
(RCA pi n jack ×2)

POSITIVE (Negative sync Provided, when terminated with 75Ω)

p-p

(Burst signal, when terminated with 75Ω)

p-p

POSITIVE (Negative sync Provided, when terminated with 75Ω)

p-p

(Burst signal, when terminated with 75Ω)

De sign & sp eci ficatio ns ar e su bje ct to change wi thou t no t ice .

2

No.51944

A

V28CH1EUS

A

V28CH1EUB

■■■■21-pin Euro connector (SCART socket) : EXT-1 / EXT-2 / EXT-3

(P-P= Peak to Peak, B-W= Blanking to white peak)

Pin

Signal Designation Matching Value EXT-1 EXT-2 EXT-3

No .

1 AUDIO R o ut put 50 0mVr ms( N ominal),

Low impedance

2 AUDIO R input 50 0mVr ms( N ominal),

High i m pe da nce

3 AUDIO L o utput 50 0mVr ms( N ominal),

Low impedance

4 AUDIO GN D ○○○

5 GND (B)

6 AUDIO L input 500mVrms(Nominal),

High i m pe da nce

7B input 700mV

8 FUNCTION SW

(SLOW SW)

9 GND (G)

10 SCL3 NC ○ NC

11 G in put 70 0m V

12 SDA3 NC ○ NC

13 GND (R)

14 GND (YS) ○ NC NC

15 R / C input R : 700mV

16 Ys i n put

17 GND(VIDEO output) ○○○

18 GND(VIDEO input) ○○○

19 VID EO output 1V

20 VIDEO / Y inp ut 1V

21 COMMON GN D ○○○

Low : 0-3V, High : 8-12V, High
impedance

C : 300mV

Low : 0 - 0.4, High : 1 - 3V, 75Ω○

, 75Ω○○NC

B- W

, 75Ω○○NC

B- W

, 75Ω

B- W

, 75Ω

P- P

(Nega tiv e g oin g sync ), 75Ω○

P- P

(Nega tiv e g oin g sync ), 75Ω○ ○ ○

P- P

○

(TV OUT)

○○○

○

(TV OUT)

○○○

○○○

○○○

○○○

○○○

○

(only R)

(TV)

○

(LINE OUT)

○

(LINE OUT)

○

NC NC

○

(LINE OUT)

NC

NC

○

(only C)

NC

[Pin assignment]

No.51944

3

A

V28CH1EUS

A

V28CH1EUB

SAFETY PRECAUTIONS

1. T he design of th is pr od uc t con ta in s sp eci al hard ware, many
circuit s and components specially for safety purposes. For
con tinu ed pr ot ection , n o chan g es sh ou ld b e ma de to the o ri g inal
d esi gn un l ess auth oriz ed in writi n g by th e ma nu fact urer.
Replac em en t p arts m ust be ident ic al to thos e u sed in th e or i ginal

ci rcu it s. Serv ice s ho uld b e p er for m ed by qu al if i ed p ers on nel
on ly.

2. Alte r ati on s of the design or ci r cui try of t he prod ucts sh ould not be
made. Any design alterations or additions will void the
manufact ur er 's warrant y and will f urth er r eliev e t he ma nu factu r er

of r esp onsi b ility for per so na l injur y or p r op er ty d am ag e r esult ing
th erefr om.

3. M an y e lectric al and mech ani ca l parts i n th e prod ucts ha ve
special safety-related characteristics. These characteristics are
oft en no t e v ident f r om v isua l i nsp ection n or ca n t he pr o tec t io n

aff or de d by th em nece ssar i l y be ob tain ed b y u sin g r ep l acement
com po ne nts ra ted f or hig he r vol tage, watt ag e, etc. R ep l acem en t
p arts whic h ha ve th ese sp eci al s afet y ch ar ac t er ist ics are
ide ntified i n the parts list of Servic e manua l. El ec tric al

components having such features are identi fied by shading
on t he sche mat ic s an d by (

manual. The us e of a sub s ti tu te rep lacem en t whi ch does n ot

h ave th e same saf ety ch ar act er ist ics as t he r eco mmen de d
replac em ent part sh own i n th e p ar ts lis t of S er vic e man ual may

cause shock, fire, or other hazards .

!!!!

) on the parts list in Service

4. Don't shor t between the LIVE side ground and ISOLATED
(NE UTRAL) side ground or EARTH side ground when
repairing.

Some model's power circuit is partly different in the GND. The
diff er enc e of th e GND i s s ho wn b y th e LIV E : (") side GND , the

ISO LATED(NEUT RAL) : (#) si de GND and EAR T H : ($) side
GND. Don't sh ort b et ween th e LIV E sid e GN D and
ISO LATED(NEUT RAL) side GND or EARTH side GND an d
n ever m ea s ur e w it h a m ea suring a ppa r atus ( osc illos cop e etc.)
th e LI VE si d e GND an d IS OLA TED (NE UTR AL ) s ide G ND or

EARTH side GND at th e s ame time.
If above note will not be kept, a fuse or any parts will be broken.

5. If any repair has been made to the chassis, it is recommended
th at t he B1 set ti ng s hou l d b e ch eck e d or adju ste d ( Se e

ADJUST MENT OF B1 POWE R SUPPL Y) .

6. The hi gh v olta ge app li e d t o th e pictu re tu be mu st confor m with
th at s p ecified in S ervi ce manual. E xcessi ve high volt ag e c a n

cau s e an i ncr e ase i n X- R ay em i ssi on , ar c ing an d possi b le
component damage, therefore operation under excessive high
voltage conditions should be kept to a minimum, or should be
preve nt ed. If s ever e arc ing occ ur s, r emove t he AC pow er
immed i ate ly an d de ter m i ne th e c a use b y visua l insp ec t io n
(inc or rect ins tal lat i on, cracke d or melte d high vo ltage har n ess,

p oor so lder i ng, et c.). To maint ai n the p roper min im u m le vel of
sof t X- R ay emi ssi on, c omp on en ts i n th e hi gh v oltag e cir c uitr y
incl ud ing t he pi ct ur e tu be must be t he e xact r ep l aceme nts or
alte rn at i ves ap pr ove d b y th e ma nuf act urer of th e c om pl et e
product.

7. Do not c hec k high volt age b y dr awing an ar c. Us e a high vol t age
meter or a hi g h v oltag e pr ob e wit h a V TVM. Discharge th e
picture tube before attempting meter connection, by connecting
a cl i p lead to th e gr ou nd f ra me and c onn ectin g th e other end of

the lead through a 10kΩ 2W resi sto r to the anod e b utt on .

8. When se rvice i s require d, ob ser ve th e or i gina l lea d dress. E x tr a
prec aut ion sh ou ld b e g iven t o ass ur e corr ec t l ea d dr ess i n the

high vol tag e c ircui t a r ea. W her e a s hort ci r cuit h as oc cu rre d,
th ose co mp on ent s tha t i ndi ca te evide nce of ove r hea ting sho ul d
b e r e pl ace d. A l wa ys u se th e ma nuf act urer's r ep l acem en t
components.

9. Isolation Check

(1) Dielectric Strength Test

(2) Leakage Current Check

(Safety for Electrical Shock Hazard)

Af ter re- ass emb l in g th e pr odu c t, al w ays per f orm an i sol at ion
ch ec k on the expo sed metal parts of t he c abin et ( a ntenn a
ter m inals, video /audio inpu t and ou tput t erminals , C on trol kn obs,

metal cabi n et, scr ew he ad s, ea r ph one j ack, con trol s haf ts, etc.)
to be s u re th e p roduct is s af e t o ope r ate with ou t dan ger of
elect ri cal s hoc k.

The iso l ati on be tween the AC pr imary ci rcuit an d all metal parts
exp osed t o th e us er , p arti cular l y any e xp os ed met al p art having a

retu rn p ath to t he chass is sho uld withs tan d a vol t age of 3 000 V
AC (r.m. s.) for a period of one second.

(. . . . W it hs tan d a v o lt ag e of 1 10 0V A C (r.m. s.) t o an applianc e

rate d up to 12 0V , an d 3 00 0V AC ( r .m. s.) to an ap pl ian ce r at ed
200V or more, for a period of one second.)
This meth od of test requi res a t est equ ipment n ot g enerally found

in t he servic e trad e.

Plug th e A C line c ord d irect ly into th e AC ou tlet ( d o not use a line
isol ati o n tr ansf or m er du r in g thi s ch eck.). Usi n g a " Lea kage
Curr ent T este r", me asur e th e lea kag e cu rre nt f rom each exp osed

metal p art of the cabinet, p art icu larly any expos ed me tal p ar t
h avi ng a re tur n path to the c h assis , t o a kn own go od ea rt h
ground (water pip e, e tc.) . An y l eaka ge curren t m ust n ot e xceed

0.5mA AC (r.m.s.).
Howev e r, i n tr op ic al area , th is must no t exce ed 0.2 mA AC

(r.m.s.).

""""

Alternate Che ck M et hod

Plug th e A C line c ord d irect ly into th e AC ou tlet ( d o not use a line
isol ati o n tr an s for m er dur ing t hi s che c k.). U se an AC vo lt me ter
h avi ng 1 00 0 ohms pe r volt or mor e s ens itivi ty in th e fo ll owing

manner. Con nec t a 1 50 0Ω 10W res ist or par a lle led by a 0 .1 5µF
AC-type c apa cit or bet ween an expo sed met al pa rt a nd a known

g ood e ar th gro un d (water pipe , etc.). M eas ure th e A C volt ag e
acr oss th e res ist or w ith th e AC vo ltm eter . Move th e r esis tor
con nec ti on to each exp ose d metal part, part ic ularly a ny exp os ed
metal p art havin g a retu rn pat h to t he ch as sis , an d m easu re th e
AC vol tag e ac ro ss the res ist or . No w, re vers e th e pl u g i n th e AC

ou tl et and re pe at eac h mea s ur emen t. Any volt ag e me asured
must no t e xceed 0 .75V AC (r.m. s.). This c orre spo nds to 0.5mA
AC (r.m. s.).
Howeve r, in tropica l are a, this must n ot exceed 0.3V AC ( r.m.s.).
This corresponds to 0.2mA AC (r.m.s.).

AC VOLT MET ER
(HAVING 1000 Ω /V,

OR MOR E SENSIT IVITY)

0.15μF AC-T YPE

PLACE THIS PROBE

1500 Ω 10W

GOOD EARTH GROUND

ON E A C H EX PO SE D
ME T AL PA RT

4

No.51944

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FEATURES

V28CH1EUS
V28CH1EUB

"

New c hass is d es ign ena bl e us e of an i nte rac ti ve on screen

control.

"

The TELETEXT SYSTEM has a built-in FASTEXT (UK syst em),

TOP (Germ an syst em) and W ST (world standard system)
system.

"

Be c aus e th is T V un i t cor r esp on ds t o m ultiple x br oa dc a st, u s ers

can enjoy music programs and sporting events with live realism.

In ad di ti on , BI LIN GUAL programs can b e h ear d in th eir or i g in al
language.

TV EXT-1 EXT-3

EXT-2

"

Users can make VCR dubbing of picture and sound by controlling

th e AV s elec tor to se lec t an optiona l so urc e at th e EXT- 2 outp ut

sh own i n fi gu re.

EXT-4

MAIN DIFFERENCE LIST

Model Name

!

Par t Name

!

FRONT CABINE T ASSY LC 10001- 008C- U LC 1000 1-00 9B-U

!

DOOR LC 20 00 1-01 0A-U LC 20 00 1-01 2A-U

!

POWER KNOB LC 30 10 4- 01 0A -U LC 30 10 4- 01 2A -U

RE A R COVER LC 10 03 -0 09 B- U LC 10 00 3- 01 0B -U

!

JV C MA RK LC 40 35 4- 00 3A -U LC 40 35 4- 00 1C-U

!

RATING L ABEL

LC 114 14 -001A -U

EURO LABEL AEM1064-009-E AEM1064-010-E

REMOTE CONTROL UNIT RM-C54H-1C RM-C50-1C

AV28CH1EUS AV28CH1EUB

LC 114 14 -002A -U

No.51944

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V28CH1EUS

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V28CH1EUB

SPECIFIC SERVICE INSTRUCTIONS

DISASSEMBLY PROCEDURE

REMOVING THE REAR COVER

1. Unplug t he po wer c or d.

2. Remove the 14 screws marked

3. Withdra w t he r ear cover to wa rd you .

REMOVING THE CHASSIS

"

After removing the rear cover.

1. Sl i ght ly r aise the bo th side s of th e c hass is by h and and re mo ve

th e tw o claws u nd er th e both sid es of the ch assis fr om t he fro nt
cab inet .

2. Withdra w t he chass is back wa rd .

(If necessary, take off the wire clamp, co nnectors etc.)

REMOVING THE AV TERMINAL BOARD

" After removing the rear cover.

1. Remov e th e 2 s cr ews m ar ked

2. Remove the claws marked

Fig. 2.

3. Slight ly in t he di re ction of ar r ow

####

as sh own in th e Fig. 1.

!!!!

as sh own in th e Fig. 1.

""""

un der t he CHAS SIS as sho wn in

as sh own in Fi g. 2.

$$$$

D

AV TERMINAL
BOARD

REMOVING THE SPEAKER

" After removing the rear cover.

1. Remov e t he 2 s cr ews m ar ked

2. F ollow th e s ame st eps when removi ng th e other ha nd speake r.

as sh own in Fi g. 1.

%%%%

CHECKING THE PW BOARD

To c h eck the b ack side of th e PW B oard.

1) Pu ll out the chassis. (R efer to RE MOV ING THE CHAS SIS ).

2) Erect the chassis vertically so that you c an easily check the

b ack si de of th e PW B oard.

[CAUTION]

"

When erecting the chassis, be careful s o that there will be no

contacting with other PW Board.

"

Be for e turning on po wer, ma ke s ur e t ha t the wi re co nn ector is

properly connec ted.

"

W hen condu cting a ch eck w ith p ow er su pplied , b e sure to c onfi r m

th at t he CRT E ART H WI RE (B RA ID ED AS S’Y) is co nne cted t o

th e C RT SOCKE T PW b oar d.

WIRE CLAMPING AND CABLE TYING

1. Be sure to cla mp th e wire.

2. Never r emo ve th e c able tie use d f or ty ing th e wires to gether.

Sh ould i t be i n adve rt ent l y remov e d, b e su re to ti e th e wires w it h
a n ew c able ti e.

C

AV SE L PWB

C

Fig . 2

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No.51944

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FRONT CABINET

S

CRT
SOCKET

PWB

FRONT
C ONT RO L
PWB

MICON PWB

10 0Hz PW B

V28CH1EUS
V28CH1EUB

PEAKER

E

POWER & DEF. PWB

C ONT RO L BASE

REAR COVER

MAIN PWB

CLAW

AV SW PWB

CLAW

FBT

CHASSIS

AV TERMINAL
BOARD

B

A

Fig . 1

No.51944

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V28CH1EUS

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REMOVING THE CRT

∗

Replac em en t of th e CRT sho uld be p er for m ed by 2 or more

p ers ons.

• After removing the cover, chassis etc.,

1. Putti ng th e CR T c hange tabl e o n sof t cloth , the CRT chang e ta ble

sh ould al so b e c over ed w ith s uch soft clot h (sho wn in Fi g. 3).

2. W hile kee pin g th e surf ac e of CRT down , m ou nt the TV s et on t he

CRT change table balanced will as shown in Fig.4.

3. R em ove 4 sc re ws mar ke d by arro ws with a b ox typ e scr e w driver

as s hown in Fig. 4.

• Si nc e the cab inet will dr op wh en scr ew s h ave b een remo ved, be

sure t o su pport t he cab inet with hands.

4. After 4 screws have been removed, put the cabinet slowly on

cloth (At this time, be ca refully so as not to damage the front

sur fac e of th e c abin et) sh own in Fig.5 .

• The CRT s h oul d b e ass em bl ed accor di n g to the o pp osite
sequence of its dismounting steps.

∗

The CRT cha ng e t able sh ould pref er ab l y be sm al ler t hat the CRT

sur fac e, and its height b e about 35c m.

CRT CHANGE TABL E

AP PROX.
35 cm

CLOTH

Fig. 3

CRT

CRT
CHANGE
TABLE

BOX
TYPE

SCREW
DRI VER

COATING OF SILICON GREASE FOR ELECTRICAL
INSULATION ON THE CRT ANODE CAP SECTION.

•

Su bs e qu ent to re pl ac ement of t he C RT an d HV tr an sfor m er o r

repair of t he an od e ca p, etc. by dis mount i ng the m, be sure to c oa t
si lic o n g re ase fo r el ectric al insu latio n as sh ow n in Fig .6.

W ipe a roun d t he an ode b utton with cl ea n and dr y cl ot h. (F ig. 6)

Coat si l ic on greas e on t he sect ion arou nd th e a no de bu tt on. At

this time, take care so t hat any silicon greases dose not stick to
the ano de button . (F ig.7 )

★★★★

Sil icon grease product No. KS - 650N

CRT

An od e b utton

Silic on greas e

coating

CABINET

Ap prox.
20mm (Do not
coat grease on
this section

An od e b utton
(No s ti cki ng of
silicon grease)

Fig. 4

CRT

CRT
CHANGE TA BLE

Fig. 5

Silic on greas e
sh oul d be coa ted
b y 5mm or m ore

fr om th e outs id e
diameter of
an od e c ap.

Coat ing posi t io n
of silico n gr eas e

An od e ca p

Fig. 6 Fig. 7

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No. 51944

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REPLACEMENT OF CHIP COMPONENT

! CAUTIONS

1. Avoid heating for more than 3 seconds.

2. Do n ot rub t he elect rodes an d t he r esis t p ar ts of the patt ern.

3. When r emovi ng a c hip part, mel t th e s older ad equate ly.

4. Do n ot reuse a chip part after removi ng it .

! SOLDERING IRON

1. Us e a hi g h i ns ulati o n solder ing iron with a t hi n po in ted end of it.

2. A 3 0 w s older ing iron is rec omm end ed for easil y remov ing p ar ts .

!

REPLACEMENT STEPS

1. How to remove Chip parts

####

Resi st ors, ca pacit ors , etc

(1) As s h own in t he f ig ur e, pu s h th e pa rt with tw ee zers and

alte rn at el y melt th e s older at each en d.

(2) Sh if t w ith tw eeze rs and r em o ve th e ch ip p ar t.

#### T ran s ist ors, diodes , varia bl e resist or s, etc

(1) Ap ply e xt ra solder to ea ch le ad.

SOLDE R SOLDE R

V28CH1EUS
V28CH1EUB

2. How to install Chip parts

####

Resi st ors, ca pa cit ors , etc

(1) Apply solder to th e patter n as ind icated in the figure.

(2) Gr asp t he ch ip p art with tw ee zers and pl ac e it on th e s old er.

The n hea t and melt th e so lder a t b oth en ds of t he chip part.

#### T ran s istors, dio des, va ria bl e r esistors, et c

(1) Apply solder to th e patter n as ind icated in the figure.
(2) Gr asp th e chip part with t we ezers an d pl ace it on th e solder.

(3) First solder lead A as indicated in the figure.

A

(2) As s h own in t he f ig ur e, pu s h th e pa rt with tw ee zers and

alte rn at el y melt th e sold er a t each l e ad . Shift an d r em ove t he
chip part.

(4) The n so lder le ads B and C.

Note : A fte r re movin g t he part , remove remain ing so lder from the

pattern.

C

A

C

No.51944

B

B

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