Monday, February 23, 2015

HITACHI CM771ET CM772ET ADJUSTMENTS AND POWER SUPPLY CIRCUIT

HITACHI CM771ET - CM772ET 

CRT MONITOR 


ADJUSTMENTS AND POWER SUPPLY CIRCUIT 

ADJUSTMENTS
1. Power supply
1.1 Standby power supply voltage adjustment.
(1) Turn the switch of the unit off.
(2) Place a jumper wire across R943, Q801 (G)-(S), I101(26pin) to GND, I740(13pin) to GND on main-p.w.b to disable Main power supply voltage.
(3) Place resister 3.9k (31W) across C971(+) to GND
(4) Receive reverse cross hatch pattern of signal 94A.
(5) Connect a Digital multimeter across C981.
(6) Turn the switch of the unit on.
(7) Adjust Standby power voltage to 6.2  0.05V using R982.
(8) Turn the switch of the unit off.
(9) Remove the jumper wire.
1.2 PFC output voltage adjustment.
(1) Turn the switch of the unit off.
(2) Place a jumper wire across Q801 (G)-(S), I101(26pin) to GND, I740(13pin) to GND on main-p.w.b to disable horizontal output and EHV output.
(3) Place resister 3.9k (31W) across C971(+) to GND
(4) Receive normal cross hatch pattern of signal 94A.
(5) Connect a Digital multimeter between + and - of C920.
(6) Turn the switch of the unit on.
(7) Adjust R919 to 364  2V.
(8) Turn the switch of the unit off.
(9) Remove the jumper wire.
1.3 Main power supply voltage adjustment.
(1) Turn the switch of the unit off.
(2) Place a jumper wire across Q801 (G)-(S), I101(26pin) to GND, I740(13pin) to GND on main-p.w.b to disable horizontal output and EHV output.
(3) Place resister 3.9k (31W) across C971(+) to GND
(4) Receive reverse cross hatch pattern of signal 94A.
(5) Connect a Digital multimeter across C972.
(6) Turn the switch of the unit on.
(7) Adjust Main power supply voltage to 85.5  0.3V using R973.
(8) Turn the switch of the unit off.
(9) Remove the jumper wire.

2. Deflection circuit adjustment
2.1 SUB H.SIZE adjustment
(1) Turn the switch of the unit off.
(2) Connect a Digital multimeter across C771.
(3) Turn the switch of the unit on.
(4) Receive normal cross hatch pattern of signal 94A.
(5) Adjust H.SIZE to maximum and S.Pincushion minimum by the Front Key.
(6) Adjust R811 to the C771 voltage value to 130  0.5V.
(7) Receive normal cross hatch pattern of signal 30C and check the C771 voltage is at 42.5  1.5V.
2.2 High voltage adjustment
(1) Turn the switch of the unit off.
(2) Connect a high voltage meter, which is capable to measure up to 40kV, between CDT anode and GND.
(3) Receive normal cross hatch pattern of 94A signal.
(4) Turn the switch of the unit on.
(5) Adjust high voltage level to 27.0  0.3kV using R747.
(6) Turn the switch of the unit off.
(7) Remove the adjustment jig.
3. Video circuit
Prior to the video circuit adjustment, all sync. and Deflection circuit adjustment must be completed. The monitor must have been warmed up for more than 60 minutes. Video signal must be terminated with 75 and should provide the correct voltage at the monitor end.
3.1 Cut off adjustment
(1) Receive a signal of 94A with a blank signal pattern. (Black video)
(2) Connect a high impedance voltmeter (more than 1000M ) to the Screen terminal (G2) on the Video board. Adjust the Screen voltage pot on FBT to see 600  5V .
(3) After the screen voltage adjustment is completed, fix the SCREEN VR(FBT) shown in Attachment A.
(4) Ambient light on the surface of the CRT should show lower than 20 lux.
(5) Adjust R, G & B, BKG to show the CIE coordinate of
X=0.313 0.02, Y=0.329 0.02 at 1.2 cd/m2 (0.35ft-L).
If it looks difficult to obtain X and Y readings mentioned above, do the followings to obtain these numbers.
1) Reset Sub Brightness to 9Fh or 60h.
2) Reset Sub Brightness to CFh or 30h.
3) If the adjustment can not be done with 1) and 2).
 1.When the value shown below can not hight: Change the R827 to R82E.
 2.When the value shown below can not low: Change the R827 to R82D.
3.2 White balance adjustment (Color 2)
(1) Receive a signal of 94A with a 100 100 mm window pattern.
(2) Set Brightness Control to the center (7Fh) and C-Cont to the minimum (00h).
(3) Adjust the light output to 80 cd/m2(24.6ft-L) at the center of screen by adjusting Sub Contrast Control.
(4) Adjust the white balance of high light output by Green and Blue color adjustments to read CIE coordinate of X=0.313  0.008, Y=0.329  0.008
(5) Adjust Contrast Control to read 3 cd/m2 (0.87ft-L).
(6) Adjust Red and Blue BKG to read the same CIE coordinate shown in 3.2.(4)
(7) Adjust Contrast or Sub Contrast Control to read 80 cd/m2(23.3ft-L) and then confirm CIE coordinate. If it shown out range, go back to 3.2(4)
(8) Register the readings of R/G/B BKG and Color data (Color 2) to the microprocessor.
3.3 White balance adjustment (Color 1)
(1) Receive a signal of 94A with a 100 100 mm window pattern.
(2) Set Brightness Control to the center (7Fh) and C-Cont to the minimum (00h).
(3) Adjust the light output to 80 cd/m2(23.3ft-L) at the center of screen by adjusting Sub Contrast Control in Color 2 mode.
(4) Adjust the white balance of high light output by R/G/B color adjustments to read CIE coordinate of 
X=0.281  0.008, Y=0.311  0.008
(Either Red color or Green color must be set to the maximum (FFh) )
(5) Register the readings of R/G/B BKG and Color dada (Color 1) to the microprocessor.
3.4 White balance adjustment (Color 3)
(1) Receive a signal of 94A with a 100 100 mm window pattern.
(2) Set Brightness Control to the center (7Fh) and C-Cont to the minimum (00h).
(3) Adjust the light output to 80 cd/m2(23.3ft-L) at the center of screen by adjusting Sub Contrast Control in Color 2 mode.
(4) Set Red color to the maximum (FFh).
(5) Adjust the white balance of high light output by Green and Blue color adjustments to read CIE coordinate of X=0.336  0.008, Y=0.352  0.008
(6) Register the readings of R/G/B BKG and Color data (Color 3) to the microprocessor.
3.5 White balance adjustment (DMS)
(1) Register Color 1 data(R/G/B BKG and Color data) to the microprocessor as DMS Color data.
3.6 Brightness adjustment
(1) White balance adjustment must have been done before Brightness adjustment.
(2) Receive signal of 94A with a blank signal pattern.(Black video)
(3) Set Brightness and Contrast, C-Cont Control to their maximums.
(4) Ambient light on the surface of the CRT should show lower than 20 lux.
(5) Select Color Select to Color 1.
(6) Adjust the light output to 1.2 cd/m2 (0.35 ft-L) at the center of screen by adjusting Sub Brightness Control.
(7) Register the readings of Sub Brightness to the microprocessor (Sub Brightness data).
(8) Set Brightness Control to the center (7Fh) and C-Cont to the minimum (00h).
(9) Receive a signal 94A with a window pattern (100  100 mm)
(10) Adjust the light output to(*1) 150 cd/m2 (43.8 ft-L) at the center of screen by adjusting Sub Contrast Control.
(11) Register the readings of Sub Contrast to the microprocessor (DMS Sub Contrast data).
(12) Adjust the light output to (*1)125 cd/m2 (36.5 ft-L) at the center of screen by adjusting Sub Contrast Control.
(13) Register the readings of Sub Contrast to the microprocessor (Sub Contrast data).
(14) Receive a signal of 94A with a full white pattern.
(15) Adjust the light output to (*1) 110 cd/m2 (32.1 ft-L) at the center of screen by adjusting ACL Control.
(16) Register the readings of ACL to the microprocessor (ACL data).
4 Focus adjustment
(1) Receive signal 94A with a full screen “E” characters.
(2) Set user Contrast control to its maximum.
(3) Set user Brightness control so that the back ground raster is just diminished.
(4) Adjust S-Focus control on the FBT so that focus at the middle points between the center of the screen to its best.
(5) Adjust D-Focus control on the FBT so that focus at four corners of the screen to its best.
POWER SUPPLY CIRCUIT 
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