NEC VT440 Service Manual page 43

TROUBLESHOOTING
LCES PWB
Are the following signal inputs available at POSV (connected with POSV of the MAIN PWB)?
(See the waveform diagram.)
NO
YES
Are the following signal outputs available at the respective output pins and test pins of IC5201
(or IC5202, IC5203)? (See the waveform diagram.)
NO
YES
Failure in the LC panel, or other LCES PWB malfunction (defective soldering, cracks in PWB)
4-3
PIN No.
• 9-14 : Rch video signal (10Vp-p)
• 22-27 : Gch video signal (10Vp-p)
• 35-40 : Bch video signal (10Vp-p)
POSV connector defective
PIN No.
• 27 : Y shift register start pulse (DY)
• 28-29 : Y shift register transfer clock (CLY, CLYB)
• 30-31 : X shift register transfer clock (CLX, CLXB)
• 32 : X shift register start pulse (DX)
• 33-34 : X driver driving direction changeover (DIRX, DIRXB)
• 35-36 : Enable pulse
• 37 : Pre-charge pulse (NRG)
• 38-39 : Y driver driving direction changeover (DIRY, DIRYB)
• TP5201, TP5202, TP5203, TP5204, TP5205, TP5206
Pre-charge level (NRS1R, NRS2R, NRS1G, NRS2G, NRS1B, NRS2B)
• TP5207, TP5209, TP5211
Panel's opposing electrode potentia (LCCOMR, LCCOMG, LCCOMB)
POST connector defective, or failure in the MAIN PWB or LCES PWB