Page 1
vf15 / FP15 / f1523 / FP5315
1) Circuit
1.
Power board operation therory ---------------------------------------------------------------------------------------------- 3
2.
Inverter -------------------------------------------------------------------------------------------------------------------------- 4
3.
Power supply ------------------------------------------------------------------------------------------------------------------- 5
4.
On-screen circuit --------------------------------------------------------------------------------------------------------------- 5
5.
Video input circuit ------------------------------------------------------------------------------------------------------------- 5
6.
Definition converter LSI peripheral circuit --------------------------------------------------------------------------------- 5
7.
System reset, LED control circuit -------------------------------------------------------------------------------------------- 5
8.
E
2
PROM for PNP --------------------------------------------------------------------------------------------------------------- 6
9.
E
2
PROM ------------------------------------------------------------------------------------------------------------------------- 6
10. CPU circuit ---------------------------------------------------------------------------------------------------------------------- 6
10.1 Dection of POWER switch status ------------------------------------------------------------------------------------- 6
10.2 Display mode identification -------------------------------------------------------------------------------------------- 6
10.3 User control --------------------------------------------------------------------------------------------------------------- 7
10.4 Control of identification converter LSI (IC306) ---------------------------------------------------------------------- 8
10.5 Power ON sequence ----------------------------------------------------------------------------------------------------- 9
10.6 Power OFF sequence -------------------------------------------------------------------------------------------------- 10
11. Audio Circuit ----------------------------------------------------------------------------------------------------------------- 11
2) Trouble shooting
1.
No display of screen (Screen is black, color of LED is amber) -------------------------------------------------------- 12
2.
Nothing displays on screen (Screen is black, color of LED is green) ------------------------------------------------ 13
3.
Checking the back light unit ----------------------------------------------------------------------------------------------- 16
4.
Abnormal screen ------------------------------------------------------------------------------------------------------------- 17
5.
No OSD display -------------------------------------------------------------------------------------------------------------- 18
6.
Abnormal plug and play operation --------------------------------------------------------------------------------------- 19
7.
Checking the interface circuit of sync signal ---------------------------------------------------------------------------- 20
7.1 Checking the control circuit of horizontal sync pulse ------------------------------------------------------------- 20
7.2 Checking the control circuit of vertical sync pulse ---------------------------------------------------------------- 20
