Used ICs: LA42205-E, LA76931, QXXAVC746-N (SMPS control), LA72703, B4L40B01500 (FBT)
The circuit board used with this TV is of Sanyo. So, when you have to enter the service mode of a Sanyo TV, using the similar kit, you can take reference these instructions to get into the service mode, and to do other adjustments. (make sure that the kit under inspection uses the same number UOC IC) LA76931. If the UOC IC number is different, these instructions are of no use with that set, but the proceedings for adjustments are almost the same too all CTVs, irrespective of its brand.This set has an On-screen Service Menu system included in the CPU that allows remote operation for most of the service adjustments.
Enter the Service Menu
While pressing the MENU button on the television, press the Number Key 2 on the remote control unit.
The Service Menu now appears.
Service Adjustments
Press the CHANNEL UP or CHANNEL DOWN button on the remote control handset to select the desired service menu item you want to adjust.
Use the VOLUME + or - to adjust the data. The + or - button will increase or decrease the data sequentially.
Exit from the Service MenuPress the CHANNEL UP or CHANNEL DOWN button on the remote control handset to select the desired service menu item you want to adjust.
Use the VOLUME + or - to adjust the data. The + or - button will increase or decrease the data sequentially.
Press the MENU button to turn off the Service Menu display.
The data which is set in the service mode is stored into the memory IC automatically.
The data which is set in the service mode is stored into the memory IC automatically.
On-screen Service Menu
Following table shows the initial values which have been stored in the CPU ROM,
and items for the service adjustments.
When IC802 (EEPROM) is replaced, check the bus data to confirm they are the same as below. The shaded menu should be checked and be set up or readjusted according to the procedures described.
Initial Setup Data marked with an * should be changed from Initial Value Data.
When IC802 (EEPROM) is replaced, check the bus data to confirm they are the same as below. The shaded menu should be checked and be set up or readjusted according to the procedures described.
Initial Setup Data marked with an * should be changed from Initial Value Data.
Click on the pictures to magnify
When IC802 (EEPROM) is replaced, IC801 (CPU) will automatically write the initial reference data into IC802 for basic TV operation.
However, the bus data should be checked and some bus data should be set up before attempting the service adjustments.
RF AGC adjustment
Do not attempt to adjust service adjustments not listed on below otherwise it may cause loss of performance and for correct operation.
1. Tune the receiver to most clearest (or strongest) VHF station in your area. Set the brightness and contrast controls to maximum. Set the colour control to minimum.
2. Select Item No. 01 [RFAGC] in the service mode.
3. Change value until the snow noise just disappears.
4. Exit from the service mode.
Horizontal phase [horizontal center] adjustment
1. Receive a monochrome circular pattern.
2. Set the brightness and contrast to normal.
3. Select Item No. 02 [H-PHA] in the service mode.
4. Change value to be optimum horizontal centre position.
5. Exit from the service mode.
Vertical shift [vertical center] adjustment
1. Receive a monochrome circular pattern.
2. Set the brightness and contrast to maximum.
3. Select Item No. 15 [VSHIFT] in the service mode.
4. Change value to be optimum vertical centre position.
5. Exit from the service mode.
Vertical size adjustment
1. Receive a monochrome circular
pattern.
2. Set the brightness and contrast to maximum.
3. Select Item No. 04 [V-SIZ] in the service mode.
4. Change value to be optimum vertical size.
5. Exit from the service mode.
2. Set the brightness and contrast to maximum.
3. Select Item No. 04 [V-SIZ] in the service mode.
4. Change value to be optimum vertical size.
5. Exit from the service mode.
OSD position adjustment
1. Receive a monochrome circular pattern.
2. Set the brightness and contrast to normal.
3. Select Item No. 12 [OSDHP] in the service mode.
4. Change value to be proper OSD position.
5. Exit from the service mode.
CCD [Caption H-Position]
adjustment
1.Tune receiver to a caption
channel.
2. Check that CAPTION position is in the horizontal center of the screen. If CAPTION center is too right or left.
3. Select Item No. 85 [CCD] in the service mode.
4. Adjust data with + or - key for proper horizontal center.
5. Exit from the service mode.
2. Check that CAPTION position is in the horizontal center of the screen. If CAPTION center is too right or left.
3. Select Item No. 85 [CCD] in the service mode.
4. Adjust data with + or - key for proper horizontal center.
5. Exit from the service mode.
Grey Scale adjustment
1.Receive a monochrome circular
pattern.
2. Set the brightness and colour to normal, contrast to maximum.
3. Enter to the service mode.
4. Set each value of Item-16 SBIAS, 17 RBIAS, 18 GBIAS, 19 BBIAS mode to 00. Set each value of Item-20 RDRIV mode to 64, 21 GDRIV to 08.
2. Set the brightness and colour to normal, contrast to maximum.
3. Enter to the service mode.
4. Set each value of Item-16 SBIAS, 17 RBIAS, 18 GBIAS, 19 BBIAS mode to 00. Set each value of Item-20 RDRIV mode to 64, 21 GDRIV to 08.
5. Select Item-23 mode to be one horizontal scanning line and turn the screen volume on the FBT to obtain just visible
one colored line.
6. Press the 1 (Red Bias +), 4 (Red Bias -), 2 (Green Bias +), 5 (Green Bias -), 3
(Blue Bias +) or 6 (Blue Bias -) button
to adjust the brightness of each color until a dim white line produced.
7. Select Item-24 DRV mode to enter the white balance adjusting mode.
8. Press the 7 (Red Drive +), RECALL (Red Drive -), 8 (Green Drive +) or 0 (Green Drive -) button, 9 (Blue Drive +) or SLEEP TIMER (Blue Drive -) alternately to produce normal black and white picture.
9. Exit from the service mode.
10. Check for proper grey scale tracking at all brightness levels.
NOTE: If the grey scale adjustment is made after picture tube replacement, check the high voltage.
Circuit diagram [Schematic] and PWB
LA76931
Service Adjustment-2 (MTS
Adjustment)
Enter the Service Menu
While pressing the MENU button on the television, press the Number Key 3 on the remote control unit. The Service Menu now appear.
While pressing the MENU button on the television, press the Number Key 3 on the remote control unit. The Service Menu now appear.
Service Adjustments
Press the CHANNEL UP or CHANNEL DOWN button on the remote control handset to select the desired service menu item you want to adjust.
Use the VOLUME + or - to adjust the data. The + or - button will increase or decrease the data sequentially
Press the CHANNEL UP or CHANNEL DOWN button on the remote control handset to select the desired service menu item you want to adjust.
Use the VOLUME + or - to adjust the data. The + or - button will increase or decrease the data sequentially
Exit from the Service Menu
Press the MENU button to turn off the Service Menu display.
The data which is set in the service mode is stored into the memory IC automatically.
Press the MENU button to turn off the Service Menu display.
The data which is set in the service mode is stored into the memory IC automatically.
Fine tuning adjustment
This adjustment is used to do a
fine tuning of the channels with poor reception after they have been stored by
the automatic tuning.
This function is available for one channel only and the fine-tuned channel is memorized into IC802 (EEPROM).
This function is available for one channel only and the fine-tuned channel is memorized into IC802 (EEPROM).
Enter the Service Menu
While pressing the MENU button on
the television, press the “4” or MENU button on the remote control unit. The
Service Menu now appear.
Press and hold the VOLUME + or
VOLUME – button on the remote control handset or TV set to make fine tuning
adjustment.
Press and hold the VOLUME + button
for higher frequency tuning, and press and hold the VOLUME - for lower
frequency tuning.
Fine tuning data value will be
automatically stored in memory.
To return to normal TV mode,
press the MENU button on the TV set or remote control handset. (Or will
automatically return to normal TV mode after 5 seconds.)
Protection Circuit
This TV set has a built-in power
supply protection circuit. It is
provided to protect the TV set in case of a power supply circuit malfunctions.
When something abnormality occurs during TV reception, the TV set goes to the
standby mode.
When an abnormality occurs during
TV reception, it causes pin 23 of the CPU to go continually Low voltage for
about one second. The CPU detects
that this has occurred and outputs the signal from pin 36 to switch off the power supply lines.
that this has occurred and outputs the signal from pin 36 to switch off the power supply lines.
Releasing the protective circuit
and restoring power supply
To release the protective circuit and restore power supply, turn the power to the TV set OFF and then ON again via either the main power switch or the ON-OFF button on the remote control. This will work only if the power supply trouble was temporary.
To release the protective circuit and restore power supply, turn the power to the TV set OFF and then ON again via either the main power switch or the ON-OFF button on the remote control. This will work only if the power supply trouble was temporary.
If there is permanent trouble
such as a damaged circuit, power cannot be restored and the circuit will have
to be repaired.
High voltage check
Note: +B (+130V) Voltage and Gray-scale Adjustment must be completed before attempting High Voltage Check.
1. Connect high voltage voltmeter negative lead to ground, and connect + lead to anode of picture tube.
2. Tune receiver to an active channel and confirm TV is operating properly.
3. The high voltage must be 25KV ± 1KV and less than 28KV at 0 beam current (Brightness and contrast minimum setting).
Note: If the picture tube is replaced, check the high voltage.
