[Tfug] LCD repair

[Choprboy]

On Monday 12 May 2008 16:54, Ronald Sutherland wrote:
[snip]
> guessing. 1 -2 sec is to fast for most heat related protection, and to slow
> for input current limit protection,  I'm going to make a wild guess that
> the DC feed (input to CCFL) is not holding up under the startup load, the
> power supply that converts the 115AC from the wall to DC (12V) for the
> display electronics and CCFL converter. To check for such things I would
> put a oscilloscope on the DC (12V) line and see if it sags or hiccups
> during startup, a DMM may also see it but may not.
>
> On Mon, May 12, 2008 at 3:49 PM, Bexley Hall <bexley401 at yahoo.com> wrote:
[snip]
> > Those in the first category I can fix.  Those in the
> > last category are *sometimes* worth the effort.  But,
> > those in the *second* category I have avoided, thus
> > far.  They *seem* like they should be an easy fix
> > (power supply problem?) since they "work" for that
> > 1-2 second period before the supply cycles.
> >
> > Any pointers?


My personal experience with several LCDs doing the power-up/turn-off mode has 
that it has always been the powersupply (ignoring the more obvious Grand 
Canyon-ish gash across the face). First and formost the slug/wallwort 
failling to provide a smoothly regulated supply (Advan LCDs spring to mind 
most often for burning out their PSs). A secondly the LCD circuit board 
fracturing at the DC plug/receptacle (just like laptops are prone too), 
leading to a high resistance or open circuit on the power input.

Adrian