Protection Circuit - Sanyo C21LF37 Service Manual

Service Adjustments
Service Adjustment-4
FOCUS ADJUSTMENT
1. Receive the monochrome circular pattern.
2. Set the brightness to normal and contrast to maximum.
3. Adjust the focus control on the F.B.T. for the best focus
on the screen centre.
T471-H3
3 3
T471-H2 T471-H1
T471
T471-H4
(FBT)
F.B.T.
T471-H5
T471A
T471-H6
T471-H7
T471-H10
T471-H8
T471-H9
T471-H11
FOCUS VR (Upper side)
+B POWER SUPPLY ADJUSTMENT
1. Connect a DC voltmetre to TP-"+B +130V" and the
ground. Set the +B adjustment control (VR651) to
middle range.
2. Set the brightness to normal and contrast to maximum.
3. Tune the receiver to an active channel and synchro-
nized picture.
4. Adjust +B voltage to 130± 0.5 volt DC by using VR651.
R/G
D1901
VOL + VOL + VOL +
J032
A1901
SW1905
L601
L601-H1
L601-H2
T4AL250V
L601-H4 L601-H3
SW601-H2
D608
R602-H7
R602B
R602-H2
C608
SW601-H4 C609
R602-H8
W601
D615
R611 R627
C614
D616
R614
R642
D617
R613
R641
C615
R631
Q613 L612
L613
C617
Q613-H6
L462H2
C442-H1
C424-H1
Q432-H3 C423-H2 C425-H1
C
B
Q432-H2
Q432-H1
Q432
C442-H3
E
H-OUT
C442-
C423-H1
JP487
JP486
C486A
L442
C420A-H1
C487
KDY
R485
R487
D485
Q432-H4
Q432-H5
4 KQ 1
VOL - VOL - VOL -
CH + CH + CH + CH - CH - MENU MENU
SW1902
SW1904 SW1903
SW190
D1902
C693
C66
RL601
C610
R602
R602-H5
C654
R602-H6
R602A
D610
D654
C658
D653
CONVERTER
C657
TRANS.
T611B
TP +B +130V
C6
T611A
R629
C651
R653
R652
R628
R103
TP +B +130V
HORIZ. WIDTH AND HIGH VOLTAGE CHECK
Horizontal Width Adjustment
1. Receive a monochrome circular pattern.
2. Set the brightness and contrast to maximum.
3. If the picture is too wide, or narrow, cut or short "JP436"
on the main unit. When JP436 is shorted, the horizontal
width increase. When JP436 is cut, the horizontal width
decrease.
Important note: When the JP436 is cut, it's gap must be
C
JP436
High Voltage Check
Note: +B (+130V) Voltage Adj. and Grayscale Adjustment
must be completed before attempting High Voltage Check.
4. Connect high voltage voltmeter negative lead to ground,
and connect + lead to anode of picture tube.
5. Tune receiver to an active channel and confirm TV is
operating properly.
6. 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. The horiz. width adjustment affects the high
voltage. Therefore, re-check the high voltage.

Protection Circuit

This TV set has a built-in power supply protection circuit.
VR651
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 stand-
by mode.
When an abnormality occurs during TV reception, it
causes pin 27 of the CPU to go continually Low volt-
age for about one second. The CPU detects that this
has occurred and outputs the signal from pin 31 to
switch off the power supply lines.
Releasing the protective circuit and restor-
ing 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 trou-
ble was temporary. If there is permanent trouble such as a
damaged circuit, power cannot be restored and the circuit
will have to be repaired.
-16-
more than 5mm to prevent sparks.
more than 5mm