Acer H15AAX Service Manual page 5

2 . 7. 4 OVP : If + 5V goes up t o o m uch, t he i n du ced vo l t age on p i n 4 o f T80 2 beco m es l arge al s o . S uppos e t h at i t i s
over 18 vo l t s , ZD8 01 co n du ct s , p i n 3 o f I8 0 1 i s pu l l ed up ov er 1 vol t . Th e pul s e t rai n at pi n 6 goes down t o
zero , s hut t i ng Q80 3 off i m m ed i at el y.
2 . 7. 5 SC P : If out put t erm i nal i s s ho rt t o g ro un d, ph o t o t ran s i s t or does n ot conduct , h en ce Q806 d o es n o t co n d uct
ei t h er. Then os ci l l at i on of I80 1 i s s t o p, s h u t t i ng Q8 0 3 off i m m edi at el y.
L i n e F i l t e r
3. On-screen circuit (Circuit diagrams Main PWB)
I3 0 0 Em b ede d f u nc t i o n.
On-s creen m enu s creen i s es t ab l i s hed and t he res u l t an t d at a are o u t put fro m I300 (C i rcui t d i agram M AIN P WB ).
4. Video input circuit (Circuit diagram MAIN PWB)
The AC -coup l ed vi d eo s i g nal i s u s ed t o cl am p t he bl ack l ev el at 0V).
5. Definition converter L SI peripheral circuit (Circuit diagram MAIN PWB)
I301 M R T V2 g m ZAN1 i s t he d e fi n i t i o n A/ D co n vert er LS I.
The anal og R , G, B s i g nal i n p u t ent ered fro m t h e vi deo i n p u t ci rcu i t i s co n vert ed i n t o t he di g i t al d at a o f vi d eo
s i g n al t hro ugh t h e i nco rp or at ed A/ D con v ert er. B as e d o n t hi s con vers i on, t hi s d e vi ce per form s i n t erp o l at i on
du ri ng p i xel ext en s i o n. The s ou rce v ol t age fo r t h i s de vi ce i s 3. 3 V an d t h e s ys t em cl ock frequen cy i s 1 2M Hz.
The wi t hs t and vol t ag e l ev el fo r t h e i n pu t s i g nal v o l t ag e i s 3. 3V and 5 V.
6. System reset, L ED control circuit (Circuit diagram MAIN PWB)
6 . 1 S y s t em res et
S ys t em res et i s perform e d by det ect i n g t h e ri s i n g an d fal l i ng o f t h e 5V s ource vo l t ag e at I302.
6 . 2 LE D co n t ro l c i rcu i t
Green / am b er i s l i t wi t h t he c on t rol s i gn al o f t h e LED GR EEN an d LED AM B ER s i gnal pi n 43, 4 2 fro m I303
(C i rcu i t d i agr am M AIN P WB ).
2
7. E PROM for PnP (Circuit diagram MAIN PWB)
Pag e 2
H 1 5 A A U / H 1 5 A A R P o w e r B o a r d B l o c k D i a g r a m
R e c .
P o w e r
&
T r a n s f o r m e r
F i l t e r
P W M D r i v e r
F B
H1 5 A AX ( AL 5 0 2 )
O u t p u t R e c . & F i l t e r
Circuit Description