Most LCD faults I have experienced are of two types
1 Dead (Psu faults)
2 Display Panel Faults
1 Dead NO pic or Snd Some have external power units, the ones with a 4pin plug are usually the fault even if they measure +12v coming out, test by substitution
The Psu are Just like any Psu using SMPS(chopper), so use normal PSU fault finding techniques Start with , Any power from secondary of chopper transformer, at the diodes) usual PSU voltages are 5v,3.3v 12v (the 12v feeds the CCF tubes power generators) If yes the psu ok, If no check for 320v across mains smoothing capacitor If 320v ok but no output, check for shorts on the output lines (schottly diodes) If the PSU is running and there are any leds glowing on the front check to see it the flurecent tubes (on each side) are glowing they usually have their own supply generators powered by 12v from PSU
Ps anyone know where to get:- schottky 120v 10a double diodes t220 case or similar?
2 Display Panel faults Vertical (source) faults are usually within the actual panel (Lines/Bands down Picture) Horzontal (gate) faults are unually within the actual panel (Bands/Lines across the screen) All faults that are within the panel aren't repairable (I know specialist repairs are possible , But the COST) there is a firm calle D'lec why not ask them for a price
Permanant Missing or Lit spots are often found , and are normal (most screens have a few) For actual usual faults check my online database for your actual make/model (if any)
