Def&Powersystem; Defboard&Hvoutboard - Ikegami HTM-1550R Service Manual

3. DEF
&
POWER SYSTEM
3-1 DEFBOARD&HVOUTBOARD
(1)
Outline
This board perfonns horizontal and vertical deflection based on the
HD and VD supplied via lhe MOTIIER BOARD.
It also generales and contro]s vollages supplied lo lhe CRT such as
high voltage.
(2) Circuit description
(a) Vertical deHection circuit
IC205 perfom1s. sync signal processing of the horizontal and verticaJ
blocks, and corrects deflection. In this IC, lhe pulse synchroni=
wilh lhe VD supplied from lhe VIDEO PROC BOARD.
This Board is crealed and oulput the saw-loo th wave.
This saw-tooth wave
is
pulled-up by IC401.
This amplitude detennines the screen
height
(b) Horizontal deflection circuit
IC205 is the center of the horizontal deflection drive circuit. By
DC-<0ntrolling lhe delay of the horiz.ontal deflection pulse (pin 25 of
IC205), lhe H.PHASE is controlled.
IC205 has a generation circuit that follows the frequency of the input
signal. The drive puJse is added 10 the horizonlal drive circuit (IR
608) via lhe buffer (fR204). Aller amplifying lhe current by TR
608, T601 and TR609 is driven.
(c) Protection circuit
When lhe high voltage malfunctions, the protection circuit increases
lhe DC voltage supplied pin 6 and 10 of!C!, to shut down lhe high
voltage output.
When no deflection pulse is output (IC703, IC53!, IC532), the high
voltage output is shut down.
CD
The high voltage output rises abnormally above the Jevel of the fly-
back pulse set
®
The pulse wave is not output lo lhe cold side of the horizontal de-
flection yoke.
@
No saw-tooth waveform is output to the cold side of the deflection
yoke, or DC bias is abnormally deviated.
(d) Horizontal centering circuit
This controls the deflection posilion by the DC current supplied lo
the horizontal deflection yoke via L602.
The control ument is generated
by
IC701.
Control is performed when the DC for H.CENT rontrol is input.
TR6!6 and TR617 are buffera.
(e) Rotation adjustment circuit
The rotation roil cancels horizonlal magnetic fields on the monilor.
The DC amen I supplied to the rolation coil is controlled by IC561.
(f) Dynamic focus circuit
IC501 is a pulse generator for dynamic focus.
It generates horizonlal and vertical parabola waves from HD and VD.
It superimposes the vertical paralx:ila wave to the horiz.onlal parabola
wave lo adjust lhe dynamic focus.
(g)
High
voltage oulpul circnil
The high voltage output is controlling by lhe high voltage stabilinltion
circuit QCl) for fly back transfonner, as well as Lhe high vollage pro-
lection and X-RAY protection.
(3) Adjustment Procedure
(a) VR213: LF
VR214 :HF
Q) Set VR214 lo the center.
®
Adjust lhe DC potential of Pin 7 oflC207 to 1.3V using VR213.
(b) VR212: H.HOLD_l
VR701 : H.HOLD_2
VR702 : H.HOLD_3
CD
The VRs for adjusting differ according to specifications.
For RI type
VR212: 45KHz HOillADJ_l
VR701: 30KHz HOLD ADJ_!
VR702: ISKHzHOLDADJ_l
ForR21ype
VR212:
30KHz HOillADJ_l
VR702: ISKHzHOillADJ_l
®
Observing the screen, adjust lhe horizontal sync using the VR cor-
responding
10
Lhe inpul signal
(c) VR207: SIDE PIN CORNER
Q) Press lhe TEST switch and select lhe CROSS HArCH signal.
®
Correct the distortion of Lhe screen romers using VR207.
(d) VR210: VERTICALS CONT
VR211: VERTJCAL C CONT
Q) Press lhe
[ill
switch and select lhe CROSS HAfCTI signal.
®
Optimize the vertical linearity using VR210 and VR211.
( e) VR603: H.D RIVE
Q) Input a signal wilh a horiz.ontal frequency of 15
kHz.
®
Flatten the rising edge of the horizontal deflection pulse at1P602
using VR603.
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