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Changhong PF29GA18A – How to enter service mode – circuit diagram – 29 inch color TV


ETA-1D chassis is applied in PF29GA18A series.
By use of Toshiba V/C/D-MCU 2IN1 IC for TV small signal processing and bus control, the chassis enables TV tuning, adjustment, control and picture correction, featuring
high-integration, high-performance-to-price ratio and high-reliability and compact circuit with fewer external components. The chassis, widely used in small and medium TVs,
provides much more convenience for manufacturing and technical service. It includes:
2IN1 IC 8897PSBNG-4VB6 for PAL/NTSC small signal processing and bus control [TMPA8897CMANG /CPANG/CRANG /CSANG]
EEPROM AT24C16 for data memory
LA78041 for vertical output power amplifying
LA42102 for audio power amplifying
TA1343N for audio processor
FSCQ1265RTYDTU for power circuit adjustment and control.
BSC68DG (FBT)
Mask ROM: TMPA8897CPBNG (ROM size: 48k)
Mask ROM: TMPA8897CRBNG (ROM size: 56k)
Mask ROM: TMPA8897CSBNG (ROM size: 64k)
OTP ROM: TMPA8897PSBNG (ROM size: 64k)
Color systems: PAL, NTSC
Sound systems: D/K B/G I M
236 programs preset
AV stereo
I2C bus control
Electronic program table
Intelligent lock
Biorhythm
Calendar inquiry.
To enter the DESIGN/SERVICE mode
Set the volume to 0.
Press and hold the MUTE button on the remote control, and press the MENU button on the TV to enter the SERVICE mode.
In this case, blue “D” is displayed on the upper center of the screen.
To exit from the D mode, turn off the TV set by the POWER button on the remote control.
Caution: The user service mode adjustment can be changed only when service personnel adjust the whole set data during servicing. As the control data have dramatic effects on functions and performance of the TV, service personnel should not tell user how to enter the SERVICE mode to avoid improper data settings.
Circuit diagram
It’s impossible to check the power part separately from the main chassis board as the part is mounted on the main chassis board. The power components, etc. should be checked for burnout when power-on. If burned out, do not power on the TV again until the cause is found out.
SMPS and system-chroma junge circuit - Split
Click on the pictures to zoom in


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