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Saturday, 31 March 2018

AKAI CT-20W9 FAULT FINDING


Multi Standard Compatible, Multi Colour On-Screen-Display, Infra-Red Wireless Remote Control , Internal / Eternal Video & Audio Input And Output

Using IC 723A 1207 as Microprocessor IC , AT24C04  as Memory,  AN 5071 as Band Switching , AN5195K-C as VIF, SIF Luminance, Chorma, Sync, Horiz & Vert Osc, MN3868 as Chroma Selector ( Chorma Delay ) , AN5534 AS Vertical Processor, LA 7952 as Internal/External Video selector, IC LA7016 as Int/Ext Audio Selector, AN5265  as Audio Output, 4 Tranasistors in Swiched Mode Power Supply

Fault Finding of AKAI



Set Dead, AC Fuse F901 Blows off
mains Plug, mains wire, on Off switch, C901
(0.47MFd). line fiter L902, degaussing coil
TH901, C902 (47KpF), BR901 (D2SBA), C908
(100MFd/400v), Q0904 (2SD249 & related
components, R916 (8M2), check SMPS section.

Dead, No Output From Power Supply
Mains wire, AC Fuse F901, On/Off Switch, line
filter L902, R901 (4.7Ω), BR901 (D2SBA),C908
(100MFd/400v) R902 (2.2 Ω), Q904 (2sD249)
R 914 (0.33Ω), R913 (330K), c912 47MFd, R912
(27 Ω) D903 (BYT52), C911 (100KpF), D902
(BYT52), Q903 (2SC1317). R910 (4K7), Q902
(2SB774T), R905 (330 Ω), c909 (10KpF), R909
(6K8), ZD902 (9.1V-zener). R908 (10K). D901
[BYT52). C9 10 (47MFd), Q901 (2SC18 15) &
related components, SM transformer, check
secondary side of SM transformer.

Power Supply Output Voltage is Less or
More Than Normal


Check AC mains supply, R901 (4.7 Ω), BR901
(D2SBA), C902 (100MFd400V), R902 (2.2 Ω)
Q904 (2SD 249). R914 (0.33 Ω), R913 (330K)
C912 (47MFD), R912( 27 Ω)  , D903 BYT52, C911 (100kpf)
D902 (BYT52), Q903(2SC1317), R910(4K7),
Q902(2SB774T),R905 (330 Ω),
С909(10KPF), R909(6K8)
ZD902(9.1V ZENER)R908 (10K), D901 (BYT52). C910 (47MFd), R906 (8K2)
ZD901 (8.2V-zenert). R907 (1K8). R904 (3K3)
R903 (1K8), VR901 (1K), 901 (2SC1815), SM
transformer check secondary side of SM
transformer, check Horiz. Output section


Only 110V Supply is Missing From
Power Supply While +16V Supply is OK

Winding between pin no. 2-4 of SM transformer is
open or def. R401 (0.68 Ω), Relay def., check for
Standby, D401 (BYV14), C401 (1K2Pf), C403
(100MFd 160v) L401, C406 (4K7pF), +110
supply line short.

Only +16V Supply is Missing From Power
Supply While +110V Suppiy is OK

Winding between pin no, 3-4 of SM transformer is
open o: det R402 (068Ω), D402 (BYV14), C404
(220pP,, C405 (470MFd 25V), check +16V suppiy
line for short.

Picture (Raster) Shaking Horizontall
Less AC mains supply, C908 (100MFd/400V)
C403 (100MFd 160V). BR901 (D2SBA). no
regulation in power supply output voltage or it is
low.


No EHT, Power Supply Output is OK
R439 (8.2 Ω /1W), C427 (100MFd/160V), Q402
(BUH575), R441 (22 Ω), horiz. Driver transformer
T401, R403 (3K3/2W), С407 (47KpF), C409
(390pF), Q401 (2S C2482), C408 (1Kpf). R409
(2K2), R408 (100Ω), R406 (15K), C435 (47Mf)
X304 (B500F), c344 (4.7MFd), R338 (10K), C343
(4.7MFd), ZD301 (9.2V-zener), R339 (120 Ω)
R340 (1K2), C331 (2.2MFd, D409 (BUY52), R434
(0.68MFd), Q405 (2SA1015) & related
components, R337 (2K2), C338 (47MFd), C337
(0.01MFd), C336 (8K2pF), IC301 (AN5195K-C)


No EHT, SMPS Output Voltage Drops
Switch off the set immediately.

Q402 (BUH575) & its mica insulation, horlz. Def
Coil, C414 (820PF/2 KV). C413 (5к6PF/2KV) C415.

(270KpF), C416 (4.7MFd), D404 (BYT52), C427
(100MFd/160V), D407-D405 (RU2). D406
(BYT52), T401, EHT transformer, check other
diodes & capacitors related with EHT winding or
+110V supply Line


Q402 (BUH575) Overheats or Blow off
Abnormal output from power supply, check Q402
(BUH575) & its mica insulation, horiz. def. coil,
C414 (820pF/2KV), C413 (5K6pF/2KV), C415
(270KpF), C416 (4.7MFd), D404 (BYT52), C427
(100MFd/160V), D407-D405 (RU2), D406
(BYT52), T401, EHT transformer, over oscillation
in horizontal oscillator, check horizontal & power
supply section


Vertical Line, Sound Normal
Minimize the brightness on the screen.
Horizontal deflection coil or its wire open, L402 (in
this case R412 (1K) starts burning), C415
(270KpF, C416 (4.7MFd), D404 (BYT52), R411
(22K)


Total Sync Loss, Sound Normal
Q305 (2SC1815) & related components, R330
(2709), C332 (1 K2pF), C331 (100KpF), R380
(330K), IC301 (AN5195K-C)& related
components

Horizontal Rolling, Sound Normal
X304 (B500F), C344 (4.7MFd), R337 (2K2), C338
(47MFd), C337 (0.01 MFd), C336 (8K2pF),R435
(3K), ZD404 (9.1 V-zener), R334 (3K), R333 (3K3)
IC301 (AN5195K-C) defective.

Vertical Rolling, Sound Normal
R341 (220Q), R342A (820K), R342 (680K), C315
(0.33MFd), IC301 (AN5195K-C) defective.

Overloading
Strong signal input, R108 (4700), C107 (22MFd)
R109 (18K), IC101 (AN5195K-C), tuner defective.


Q904 (2SD249) Overheats or Blows off

Q904 (2SD249) & its mica, C913 (1K5pF/2KV),
C908 (100MFd/400V), BR901 (D2SBA), C902
(47KpF), L902, C901 (0.47MFd), C912 (47MFd),
C911 (100KpF), D903-D902-D901 (BYT52), C910
(47MFd), ZD902 (9.1V-zener), ZD901 (8.2V-
zener), Q903 (2SC1317) & related parts, Q902
(2SB774T) & related parts, Q901 (2SC1815) &
related parts, SM transformer, check secondary
side of SM transformer, check horizontal output
 

No Regulation in SMPS Output Voitage
VR901 (1K), R903 (1 K8), R904 (3K3), D901
(BYT52), C910 (47MFd), Q901 (2SC1815), R907
(1K8), ZD901 (8.2V-zener), R909 (6K8), R906
(8K2), R908 (10K), R909 (6K8), ZD902 (9.1V-
zener), C909 (10KpF), R905 (330 Ω), Q902
2SB774T), R910 (4K7), Q903 (2SC1317), DR912
(27Ω), D903-D902 (BYT52). C911 (100KpF)
C912 (47MFd), Q904 (2SD249), SM transformer,
check other components of power supply section

Set is in Standby i.e. No Power-On
+16V supply from SMPS is missing, R601
(18 Ω/1 W), Q501 (D400), R804 (1K8), C6 1 4
(10MFd), C615 (0.01MFd), L623, Q603-Q602
(2SC1815), R608 (10K), C621 (100KpF). R607
(30K), R606 (10K), C603 (47MFd), R605 (560 Ω).
ZD601 (8.2V-zener), SUB POWER key, check key
matrix circuit, X601 (6MHz), C619-C618 (33pF)
no output from pin no. 11 of IC 723A 1207, IC
723A 1207 def., R634 (3K3), D607 (1N4148),
C601 (100MFd), R602 (3K3), Q607 (2SC1317),
D403 (1N4001), R403 (68 Ω), Relay defective


No Operation Through Remote Control
While Handset is OK and Front Panel
Keyboard is Working Normally

R616 (100Ω), C607 (47MFd),no output from IR
Remote Sensor or is faulty, Q605 (2SC1815),
R612 (10K), C620, IC 723A 1207 defective
 

Remote Control Operation is OK But No
operation Through Front Panel Keyboard

Any key in Front Panel Keyboard is def., keyboard
dusty or rusty, check key matrix circuit, R624-R623
(1K), R626-R625 (2K2), R622-R621 (3K3), R633
|(1K8), С601-C602 (150pF), X601 (SMHz), C619.
C618 (33pF), IC 723A 1207 defective
 


Channel/Program Up/Dn is Not Possible
CH+/CH- key def., check key matrix circuit, R624-
R623 (1K), R626-R625 (2K2), R622-R621 (3
R633 (1KB), C601-C602 (150pF), X601 (6MHz)
c619-C618 (33pF), IC 723A 1207 defective

EHT & Sound is OK But No Light or
Low Light or Brightness Problem

Adjust screen control, check CRT filament supply
R507(0.15
Ω), check CRT Screen & Focus grid
supplies, Q505 (2SC1815) & related components
Q504 (2SA1015) & related components, check
-9V supply, R427 (0.68
Ω), D407 (RU2). C428
(1000MFd/25v),Q404 (2SD400) & related
components, R430 (27
Ω), Q305 (2SC1815) &
related components, Q304 (2SC1815) & related
components, C325 (10MFd), R325A (33K), R379
(180K), C326 (1KpF), Q301 (2SC1815) & related
components, IC301 (AN5195K-C) & related
components, IC 723A 1207 & related components
CRT base loose or faulty, check CRT earthing,
CRT defective


Retrace (White) Lines, Sound Normal
Adjust screen control, R425 (0.68. D406
(BYT52), C425 (10MFd 250V), L501, Q505
(2SC1815) & related components, Q504
(2SA1015) & related components, C426 (56KpF)
R437 (10K, Q301 (2SC1815) & related
components, IC301 (AN5195K-C) & related
components, CRT base loose or faulty, CRT
defective

Retrace Lines With Picture at Top Portion
of the Screen or in Full Screen

Adjust screen control, D405 (BYV52), C419
(100MFd), C423 (1000MFd), IC401 (AN5534),
also check as given in above fauit.

Raster & Picture Normal, No Picture,
Weak or Poor Contrast/Contrast Problem

Q305 (2SC1815), Q304 (2SC1815), R318
(560
Ω), L301 & CF309, L309 & CF308, C325
(10MFd), R361 (680K), R325A (33K), R379
(180K), C326 (1KpF). C324 (0.47MFd), C315
(470MFd), C314 (0.01MFd), check Contrast
control circuit at System Control secton, Q301
(2SC1815), R307 (1M, C316 (47KpF), IC301
(AN5195K-C) & related components

No Picture, No Sound, No Snow, Raster OK
S AW-Filter K2955, R112 (470 Ω), T301, C328
(4.7MFd), check circuit related with various
terminals of tuner, IC AN5195K-C & related parts

No Picture, No Sound,
Only Snow or Picture With Snow

Antenna & wire, balun/adapter, adjust fine tuning
check Band Switching & Tuning Voltage circuits at
System Control section, R433 (220), tuner
defective, SAW-Filter K2955, C107 (22MFd), R108
(470
Ω), Q102 (2SC1815) & related components
Q606 (2SC1815) & related components, check
AFT circuit, IC301 (AN5195K-C) & related parts





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