Akai CT 2870 UK, CT 2570 UK Service Manual

MANUAL

1 Stereo module

69113789

RF-IF module )

5829 02 58

CT 2570 UK

Ident-Nr. 5436 03 00

CT 2870 UK

Ident-Nr. 5436 03 10

Replacement parts list

When ordenng spares please quote item and order number. When ordenng (sub-)assembks (modules), gwe the assembly number in addition!

A Safety components in accordance with existing regulations. These components must only be replaced by original component parts

CT 2570 UK CT 2870 UK

Cab,net 61128636 Cablnet 61122861
Front plate 64172606 Front
Loudspeaker blind 64110720 Loudspeaker blind 64110721
Operatlnq ““0 lid
Holder for operatmq un,t Ikd a681 10 06 Holder for umt I!d operatmq 8681 1006
Grille for mdlcator a251 44 19 Grille for lndwxtor a251 44 19
WIndow for lndlcator qrllle 6466 37 36 Window for lndlcator grille 6466 37 36
Pad 8642 0148 Pad a642 0148
Rear couer
Holder for rear cover 8624 47 10 Holder for rear cover 8624 47 10
Screw for pcture tube
Picture tube A 59 ECF 00 X 01 SEL A 43622555 Plcture tube A 66 ECF 00 X 01 SEL A 43622803
Earth for plcture tube 6141 0305 Earth for tube
Sprlnq devtce for earfh,“q 735128 46 Spnnq dewce for earthmq 7351 28 48

Deqausslnq co11 A 45880524 Holder for picture tube 8623 3140

Hook for deqausstnq coil 868172 15 Deqausmg cal A 4588 05 24

Loudspeaker
Holder for loudspeaker 73680196 Loudspeaker an. IOW 431107 15

Chaws conduct, left 8625 11 63 Loudspeaker 4 S!. 10 w 43110921
Chassis co”duct. rlqht 86251164 Holder for loudspeaker 7368 0196
Holder for STEREO-Modul 8625 48 09 Chassis conduct. left 8625 11 66
Plunger pi” for RF module a642 75 05 Chassis conduct, right 8625 1165
Matns pushbutton 631536 la Mains pushbutton 631536 18
Holder for decoder 8625 47 07 Holder for STEREO-Modul 86254809

89.15~

86870281

6214 $068 Rear ccwer. qrey

78640221

43110715

plate

Operattnq U”,t Ild a687 02 a2

Screw for picture tube

pxture

Hook for deqaussmq toll

Plunger PI” for RF module a642 75 05
c 3951396 2.2 UF 100 V 342175 52
Holder for decoder 8625 47 07

64172985

62140959

18640221

6141 0305

86817215

When re-ordering manuals, please quote the model name and part number.

66117924(104)S

Picture and sound IF-adjustment

Required measurmg equipment:
sweep generator Wlfh marker

tr=“Smltte,
SIgnal generator.
Oscillograph:
RF rectifier probe
B!as voltage ,nstrument

Stage to be

NO.

adjusted

1 1

UHF/IF filter

Test arcu~t 1. Sweep
, gen. “,a 15 pF to TP 2
/ (UHF tuner) approx
I 300 mV TP 203/204 to

30 42 MHz. max. output 200 mV
5 5 MHz. dispersion k 15 kHz, f,,. = 1 kHz
Sens~t~v~ry 10 mV/cm 1 V/cm

adjustable from 0 10 V

Connect. oscillor.

Osc~llo. “,a probe to
TP 101/102 Ampiltude (VC and SC must have the same helghf) Bandwtdth can be
10 mV/cm See Fig 1

Preparations:
!&as voltage instrument to TZ 214 Check U V 12 V i 10% at TZ 23 The cores

must be at the upper end of the co11

Adjustment procedure ~ Oscillograms Remarks

I

Adjust to max. amplitude and level roof with L 62and L 64
narrowed wth L 63.

I

UHF/VHF/IF-

12

filter

2 Reference circuit

Monitoring of IF x

3 1 frequency

response gen. via Interstage transf Osc~llo to T 24

52 DF-AF

Some voltage
level from sound

5.3

channel 1 and
channel 2

1 Monitoring of

60

video signal

1 Test c,rcu,t 1 Sweep ’ Osc~llo. “,a probe to

en. “aa 10 nF to TP 6 TP 2031204 Amplitude Adjust to max amplitude and level roof wth L 161 and /

I g

(UHF tuner) approx. approx 20 mVicm L 162 (BT and FT must have the same height)

20 mV TP 4 to earth

Test c,rcu8t 2 Sweep 1

gen "Ia mterstage

transformer (4.1) to

TP 2011202 (approx.

20 mVI

Attenuatnn xc. tq test ClrCult 3. TP 102 to earth wa ’ (
) 2.2 “F’

/ Test circuit 2 Sweep ~
~ (4.1) to TP 2031204

(approx. 150 mV1

SIgnal generator

( ~zx;,;k~; osz”‘o to Tz33

I

Signal generator5.5 MHZ
on TP 211 and 5.74 MHz

~ on TP2,2

With the ald of a standard modulated N transmitter. the video output voltage should be 2 V,, + 0.2 V

1 See Fig 2
I

Osc~llo to TZ 24 Tune frequency marker 38.9 MHz to max amplttude with ~
Amplitude 450 mV/cm L206 (UK = 39.5 MHz)

Set frequency marker 36 MHz to 1.7 V,, - 0 d0 with bias
voltage at TZ 214 Marker 36.9 MHz should Ile between

- 5 dB and - 7 dB. marker 34.5 MHz between - 3 dB and

Amplitude 0.5 V/cm

Osc~llo to TZ 31 Adjust R 233 on 761 mV,,.

Osc~llc to TZ 31 and
Ti! 33

- 5 dB.

I

’ / Tune L 226 CL2361 to AF max. and ml” dlstortlon factor 1

Tune sound channel 2 wth R 225 (R 233) to have the same

haght wt sound channel 1 (appr 1%).

A “,

I

I

Swtch the respectwe term,“& of
TZ 3liTZ 33 to earth v&h 10 nF
capacitors

389YHI

-“.- ~.,-“m,

Y,5”*2

Abb. 1

Probe for RF tuning

Test circuits 1

Abb. 2
Probe for tuning of the IF coil

Test circuits 3

_. _ _ _ _
MS, PARALLELTON 5T”FE
(51 PARALLEL SOUND STAGE

Instructions for dismantling:
Turn the two red plunger pins by 90” Remove module from

bracket (Fig. 1).

1. Apply pressure to the plate channel simultaneously with both
thumbs, until the cover seaming bends, then remove cover
(Fig. 1).

2. Before the cover can be put back on, the plate channel must

I

first be pressed back into its proper position from the InsIde
(Fig. 2).

3. Put cover back on.

Raststift
Plunaer p,ns

Ambedue le spme

Gegenstand
Item
Pike
Ricambi

HF-ZF Modul (Kabeltuner)
RF-IF module (Cable tuner)
Module HF-BF (Tuner rhseau cable)

pour

Modulo MF-BF (Tuner a larga banda)

IC 161 TDA 5030
IC 171

IC 201 TDA 4427 A
IC 202 TDA 2546 A

Tl BF 989
T, BF 996>E 6327
T 41 BF 569-L

T 61 BF 569-E 6327
T 162 BF 550

T 163 BC 848 AF
D 1 21 22 41 EB 221-S?

U664B

Bestell-Nr.

1 Order no.

N‘ de corn.
No. di rif.

5829 02 58

MOS 3775 05 73

MOS 36110711 F 201 J OFW 3203

3761 1725 L 211
3761 1623 L 244 I

3761 1358 F 201 OFW G 3205
361107 13 F 202 Filter ’ F,lter I Fiitre

36120711
361207 13

3612 07 25
36145321
3651 0525

I

~

Gegenstand
Item
Pi&x
R’cambi

D 160 161 LL 4148
L 202 Drossel i Choke 1 Bob
L 2051245 F~ifer / Filter / Flltre /
L 206
L 207 Drossel i Choke I Bob de se” i Bob,na I
L 210 DrosselI Choke 1 Bob

L 226 236 1 1 Filter Fflter Flltre i Fllfre 5.5 MHz 4555 30 24

Anschlufllelste 34pollg Female piug 34fold
Reglette a doullles. 34fo1s I Sp~noft~era 34~011

G?hausedeckel Cabinet can top
B3her parte super~er I Coperchlo schermatura

Antennenbuchse Antenne socket I 41439045
PIIse pour antenne I press per antenna

Filter ! Filter / Flltre i F,ltre 38.9 MHz ~

Spule i Co11 i Bobme i Bob,na
Drossel Choke Bob f de sell Bobina / 4557 16 25

’

Bestell-Nr.
Order no.
N de corn.
No. d, rd.

de sell 1 Boblna ~ 4557 16 29

Filtre 38.9 MHZ 45553022

de setl i Boblna ~ 4557 16 25

F~ltre

36560311

45553023
4557 1649

4544 07 46

45558552
4555 85 53
4555 84 15

41451675

i 83164501

L

I---+

UHF “DRSTUFE

UHF PREAMPLlFiER

RF-IF module

5829 02 58

n-n--.-- -

E

K

h

-- _--. ___

2

”

Stereo module/C

6911 37 69

II I

After changing or repaiflng a module,

Pllo, *Igtul l Ilgnment

check

the oscillator frequency and adjust if necessary.

F.­,.-

;\

6

-----

1

I

I

18

AMPLITUDENSIEE, HOR U “ERT OSZltLATOR
SYNC SEPARATOR HOR A “ERT OSClttATOR

TDA 8371

CIRCUIT0 ALiMENlAZtONE RRE

Please note:
When exchanging T 701. IC 701 must likewise be
exchanged.

e

----P----P.-~-.

NETZVERWNDEN / MAINS CONNECTED

COLLEGATO ALLA RETE

NETZGETRENNT i

Chassis Compact D/2 FST

P1

69’

swttc

POS

*WI

401

SC

i

-as

605

11

a.*

101

5861 75 22

K 3101

TEAZOlLA ,

VIDEO-SCHALTER

3

VIDEO-SWITCH

1 I”

.Q 12”

r

A-

B-

VeR Amplotude

1

9

a

0

CD

e

Vert. ampl,t”de
Amolltude vert
Ambezza verwale

Her Amplitude
Her amplitude
Amplatude her
Ampiezza onzzontale

Vert EMage
vert picture slvft

“BR de I image

Pos verncaie lmmaglne
HOT 811dlage

Her picture shift
Pas her de ,‘,mage
Pos OrlzzOntale lmmaglne

Vert Frequenz
vert frequency
Frequence vert
Frequenza verwale

HOT Frequenz
Her frequency
Frequence her
Frequenza or,zzontale

Sandcastle

A

- NF-Sagn

- ~2;L,”

-~ vert Imp

AF sign
BF sag”.

Camp colour stgn

CLSS i CLSS

With the equpment

-i

0

0

.-

.-

865

0

.--

~-

--

CompacI- Chassis D/Z llO”- FST

5661 75 22

PAL Decoder

GIOC

Bell-j

6911 30 28

R410 2:

@ :v
8 1:;
Q ii

PAL - DECODER

With the equipment switched to stand-by, the voltages of the switched-mode power supply and the horizontal output stage are below nomlnal value.

Vert Amplitude
‘Jerl ampl,tude

Amplcude ven
Ampiezza

vmcale

Hor Amplitude
HOr ampl,tude
Amplntude her
Amplezza cmzzontale

Ven Frequenz
ven. frequencv
Frequence v&t
Fwquenza verwale

Her Frequenz
Her. frequency
Frequence tvx
Frequenza orizzontale

Sandcastle

NF-Stgn
AF s,gn
BF sign

BF sign
FBAS-s,gn.

Camp coio~r sign

CLSS i ass

kl Imp

Her mp

lmportanl

Follow,~g exe
c r t board h;

Thedexder
Standard PAI

mum ad br,;

-

FHT-I
Sub-8
Oscil
Oscil

PAL­PAL I
Demo
Demo

Filtre
Fillrc
(D.X
(Deem

SEC1
(Dee’
(oec

SEC1

(Dee
(DW

-

CRT. base board

_--~-.-.-.-.-.--.-.-.-.-.- .-.---.-. --.-.-,

IVIDEO ENDSTUFEN UND EILDR6HRENANSCHLUSSPLAnE
wlE0 oum STnGEs AN0 PICTURE TUBE CoNNEcTlffi BOARCJ
,STADlO FINALEvlDEO E PlpsTRA COLLEGI\MENTO DEL CINESCOPIO

Important:

Followg exchange or repair of the colour decoder. ensure that the adait~onal earth connection
c r t boara has been re-establlshea before swltchxnq on the set

The de:.oder waveforms are taken under following conalt,ons
Standard PAL that IS. SECAM coiour bar pattern. contrast at maxi­mum aid brightness and colour saturation at nominal value

PAL SECAM Decoder 6911 30 3016911 30 29 “9 - 12 V kontr.,cont

FHT-Oszillator
Sub-carrier oscillator
Oscillateur FHT
Oscillatore FHT

PAL-Dematrix
PAL dematrix
Dematrice PAL
Dematrice PAL

Glockenlilter
Bell-jar filter
Filtre de c&he
Filtro a campana
[Decoder 6911 30 30)
[Decoder 6911 30 29)

SECAM-Discrim. (R-Y)
[Decoder 6911 30 30)
pecoder 6911 30 29)

SECAM-Discrim. (B-Y) /
[Decoder 6911 30 30) 1 L 835
(Decoder 6911 30 29)

c 875

LB84

~ R 883 verschwndenae Jalouse I”, Feld + V i ” /

I

j LB10
1

/

i j

L 830

annaherna stehende Farblnformatlon
near stationary colo”rs
sur I’mformatlon de couleur presque stable
su Inf di coiore appross,mafa

verschwlnaende &louse urn Feld .G-Y - 0”
minimum Hanover bars I,, “G-Y - 0’
SLIT ~&USE dlsparalssante dans
I” mod0 da ottenere una spar,z,one delle str~sce nei campo <<G-Y = O>,

m~“r”“m Hanover bars I” + V i”
sur jalousie alsparaxsanle dans le champ + V i u
I” modo da ottenere una

DaR die Amplitude belder Zellen be1 schwarz/welR und wahrena des Frequent-Nulldurchganges
glelch

slnd

I That the amplitude 01 both lines IS the same with blacklwhw and during zero frequency passage

De SOrte q”e les amplitudes des deux lignes Solent identtques. en “nr et blanc et durant le passage i anderschrelben.
par zero de ia frequence
Che I’ampiltudine dl ambedue ie rlghe nel case di blanco e nero e durante 11 passagglo aella

frequenza per IO zero 518 uguale

Schwarz- u WelOpegel = deckungsglelch zu Austastpegel
10 where the black level and the white level coincide on the blank,ng leve,
i I’egal~satlon du wea” “01r et nfveau blanc qu’ll sort s~tue au niveau de suppression
I” mado the II l~vello del nero e quello de1 blanco siano congruentf sul l~vello d, tancella~~one

PAL Decoder 6911 30 26/6911 30 26

ie

Champ ‘<G-Y = 0,.

spmmne

delle str~sc~e nel campo + v t u

\

FuBK-Testblld
! Test picture
) mre
1 mmag~ne di test

~

OSCL - a10

0

Zwe~ Zellen “berein- rmre de couleur

Adjust to converge two

consecuf~ve lines

Ecnre 2 ilgnes i’une sur

I’autre

Scrwere 2 rIghe ““a

sovrapposta all’altra

SECAM-Farbb
Colour bar sfgn

bane df coiore

r

Indicator board

--

0

51‘01

n

IFB 473 UK

58831490

LTO 6LtO G

Awl

Program board

Indicator board, IFB 473/483

Base board

Hint for

antenna

Because of the ever mcreas~ng number of lnterferance sources and their negatwe etfe
only shlelded (75 ohm) antenna cables and antenna plugs (DIN 45325) should be use,
possible Interference suppress!on Unshielded antenna cables. balanced-to-unbalam
and antenna plugs often prove lnsufftclent for In!erference-tree reception.

Repalr tips

1. With dlsconnectedswltchlng stage T 701 (base open), the power supply 15 capable 01
As no output voltages are generated I” this co”d,t,o”. the IC 601 IS wlthout SUPPly “(
m other words. the power supply is not synchromsed.
Rectangular pulses w,th approx 14.6 kHz are measureable at Pin 14 (IC 7011.
However. the IC operates I” so-called Interrupt mode, 1.e the pulse voltage at Pin ’
200 ms.
N. B. If the swtchmg stage IS dlsconnected. the electroiytlc capacitor C. 656 mi

re-con”ectnon (soldering)

2 With disconnected hotl?ontal cutput stage ,e.g termma, 4 Tr 501 open, and a repla

of D 733 (60 watt lamp). the power supply delivers approx 110 V (Compact D) ca.

3 If the T701 (ON 4046) falls repeatedly. the followng components should be replac

even If these are OK according to the ohmmeter, and C 704

4. For servnng the set under operatong condltons when the election~c fuse has a<

~CIOSS C 700 (C 713) If the eiectronlc fuse cuts out due to a momentary over1
re-started by swltchmg the mans swtch off and the” on agal”

connecttng

.

Chassis board / CRT. base board / Color decoder board

4

FLOF decoder
6911 1159

SAA

j2LO PIA

SAA

5210 PI0

cm
SW RAM
STATIC RAM

m BUS-WANOLER

BUS-CONVERTE
IM BUS -mm

I

I

m 25 I+T ERZEUGUNG FUR

g

.

ZWISCHENZEILENABSCHAL~UNG

-

NNUNG OER VT-SIGNALE I

a VT-PROZESSOR

-PROCESSOR

Cz.0‘1

, 12

B

33

2 1

C30‘2

‘6 NAB 8‘61 28

.I

2

I3

L

n

M03

Pay attention to protective measures for MOS components!

u

BUS-WANOLER
BUS-COlrVERTER

IM BUS * !a BUS

I

Decoder

IC 3001 TEA5114A 3766 11 53
IC 3002 SAA 5231 MOS 3779 15 38
IC 3003 SAA 5240 MOS 3779 15 40
IC 30M CXK 5864 AP 10 L MOS 3776 01 59
IC 3005 MAB 6461 P MOS 3777 51 21
IC 3006 MEA 2050 MOS 3779 11 61
IC 3007 SAA 1272 C MOS 1 3779 11 31
IC 3006 3011 HEF 4001 BP MOS ~ 37715107
IC 3009 HEF 4006 MOS 377151 a9
IC 3010 L 7805 ACV MOS 3768 17 65

T 3001 .3004.3006 BC 048 B I 36145322

3007.3009
T 3006.3011 BC a58 c 36145423
T3010 BC a47 c

69111159

36145313

I

D D 3001 3002 ZPD LL 4148 3.3 F i 36560311 36531744
L 3001 Drossel / Choke I Bobma 4557 17 62

L 3002 Drossel i Choke i Bobma 4557 16 66
L 3004.. .3oc6 Drossel / Choke I Bobma 4557 16 37

x 3001
X 3002

IC-Fassung. 14 pol!g / IC socket. 14 fold 41563075
Zoccolo del IC. 14 poli

IC-Fassung. 16 pollg I IC socket. 16 fold
Zoccolo del IC. 16 poll

IC-Fassung. la poilg 1 IC socket. 18 fold

zOcCOl0

del IC. 18 poll

IC-Fassung. 40 pollg 1 IC socket, 40 fold
ZocColo del IC. 40 poll

Kuhlblech fur IC 3001 / Heat sink for IC 3001
Aletta dl raffreddamento per IC 3001

Ouarz i Quartz / Quarzo 13.875 MHz 4421 31 07
Ouarz / Quartz / Quarzo 6 0 MHz

/

/

442131 a0

41563076

41563077

41563080

65247303