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sanyo tv ce28wn5

Discussion in 'Electronic Repair' started by Peter hancox, Feb 16, 2006.

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  1. Peter hancox

    Peter hancox Guest

    hi any help this set used to flash blue with white lines down screen then go
    out of focus checked crt pcb and blue voltage is missing and feed resistor
    is getting hot need schematics as has alot of smd components...thanks!
     
  2. JANA

    JANA Guest

    Tap on the neck of the CRT to see if the fault is able to be provoked. There
    is a good chance that the CRT is failing.

    --

    JANA
    _____


    hi any help this set used to flash blue with white lines down screen then go
    out of focus checked crt pcb and blue voltage is missing and feed resistor
    is getting hot need schematics as has alot of smd components...thanks!
     
  3. Peter hancox

    Peter hancox Guest

    cheers ! think its crt as the large resistor on blue feed on crt tube pcb
    gets very hot when blue screen appears
     
  4. Jeff Rigby

    Jeff Rigby Guest

    Picture tubes are usually kathode driven. Which means that turnoff is
    usually 200 volts and turn-on is a function of how low the voltage goes.
    Some value close to zero is full beam current. The video out transistor can
    short or the picture tube (heater to kathode) can short bringing the voltage
    low. An easy check is to unplug the CRT drive board from the crt and
    measure the collector side of the resistor for blue. IF it still goes much
    below 130 volts then the transistor or drive circuit has a problem. IF not
    then it's probably the tube. In that case you can get a isolation
    transformer for the picture tube heater and this will generally fix the
    problem. There might be a slight smear but since it's blue you won't notice
    it.
     
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