Flickering LCD screen on electronic power switch

Discussion in 'General Electronics Chat' started by Glitchmobile, Nov 28, 2010.

  1. Glitchmobile

    Thread Starter New Member

    May 8, 2010
    As per the attached photos, this is a basic timer circuit exposed from a
    wall-wart AC power switch timer. Up until recently, it would work
    well with the replacement of of a 1.5vdc memory battery. However,
    replacement of the battery does not repair it any more. The LCD screen
    merely flickers. None of the touch pad sensors makes any effect, except
    the reset button. This cause the screen to go blank and then come back
    on with a continuous flicker.

    Anyone know what could cause the unit to go into flicker mode? Faulty
    capacitor on the back side of the circuit?
  2. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    There will be a chip between the screen and PCB. The flicker may be due to ur florescent tube refresh freq which is at your mains AC freq.
    And could be tht the LCD refresh is almost close to that or half of tht or something.

    Either way this is beyond anyone since chip is sealed. Like black blop thing.
    If there is no electrolytic cap try replacing it.

    My guess is as good any others, with those pictures
  3. PackratKing

    Well-Known Member

    Jul 13, 2008
    There is a carbon / silicon connector strip between the lcd and the pcb, which is a "pressure" connector......if the item is dropped or subjected to any such shock, these can instantaneously break / remake contact, and then it is sheer pot-luck to get the device working at all.

    It is next to impossible to dismantle and clean the lands on the lcd that rest on the silicon connector, as the trace connectors doped / deposited ? on the glass are hideously fragile, or I've not had a whole lot of luck cleaning them.

    This is a notorious fail point, specifically in Western Pacific electronics. :eek: Lcd's from there just don't seem to have enough " beef " to be serviceable.
    Last edited: Apr 13, 2011
  4. Glitchmobile

    Thread Starter New Member

    May 8, 2010
    Thanks for the input. I kind of figured it would be impossible
    to fix, based on the micro scale of the components and respective

    Just a quick note about the flicker; it occurred while
    the circuit was battery powered, no AC mains.

    Anyways, chalk one up for built in obsolescence.
  5. retched

    AAC Fanatic!

    Dec 5, 2009
    It looks like the PROG trace was cut or scratched pretty bad.

    If it is getting an intermittent connection, it my be causing some erratic behavior.