Vertical And Horizontal Drive - Hitachi 36SDX88B Service Manual

8. Vertical and Horizontal Drive
Pin Description : See drawings as shown below in detail.
Function : See drawings as shown below in detail.
Signal Flow :
See
below.
Vertical and Horizontal Drive Siqnal Fiow
1001
MN1 02t35GHE
Micro SCL
l
SDA '
I
'so1
UPC1885
1. :",4,1",
Sync Control t-l Out
H/V Sync in
I
//
I/
I
'601 1 Vout )
LA7846N
V position
V position
1 Vout 1
Control
Q603 / Q604 I Q605 Control
b
Transistor
*VDY
V position Control
Description
V Drive The vertical sync signal from TV /PC sync circuit is input to IS01 pin #28 on Sync
PWB. IS01 make vertical saw tooth and it is output at IS01 pin #8 to 160-l pin #6.
H Drive The FBP (Fly Back Pulse) is applied to ISOl pin #'l7. East/West out is output at
IS01 pin #9 to operation amplifier lSO2. It is amplified by ISO2, then output it at
IS01 pin #I to IPOI pin #14. Side pin drive pulse, which is modulated with
vertical East I West, is output at IPOI pin #7 and controls +8 voltage. H out is
output at IS01 pin #I8 to Q701 base.
V Position The vertical position circuit composed of 1005, Q603, Q604, and Q605. The
vertical position output from 1005 pin #I7 varies the base of Q503, which changes
the DC bias being added to the V DY by Q604 and Q605 through R611, R612,
R613, and R614 to change the vertical position of the picture.
VERTICAL DEFLECTlON ClRCUIT(LA7846)
A vertical sawtooth voltage is input at pin (6). At the start of the retrace period a pulse voltage
occurs at pin (3). This voltage is added to the voltage across C606. The sum is approx. 50V
which is necessary for during then retrace period. C606 then discharges and the cycle starts
again.
105