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Dear Sir, We are suppliers of heater & cathodes to 14" color Tube manufacturers.Our customer has experienced Retrace lines in tubes.When the heater & cathode of these tubes were opened we found both heater & cathode puncture.Also when we inspected our fresh heaters before assembling it to guns we found coating chipoff(insulation cracks).Is this the reason causing for short between heater & cathode due to which both heater & cathode are punctured or is there any other reasons for heater cathode short & puncture & Retrace lines.

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  • praveen_prab Feb 14, 2009

    Retrace lines - My question was does insulation crack/damage to heater leads to Retrace lines.If yes kindly explain to us how it leads to Retrace lines.
    Also as i mentioned earlier when we opened the heater & cathode we found puncture both in heater & cathode which has led to short & then retrace lines.Kindly let us know why this puncture occurs i.e. reason for puncture of heater & cathode.

  • praveen_prab Feb 14, 2009

    In some guns when we opened we have found only heater puncture at the apex & there is no puncture in cathode,in some there is puncture in both which leads to retrace lines.Kindly let us know if there is any other reasons for this to happen.

    Also in some guns when we opened heater & cathode we have found black patches on heater it is somewhat like heater burnt which has lead to retrace lines.Kindly let us know what is the reasons for this to happen.

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Hi and welcome to FixYa,

This is more of an engineering design rather than a repair issue. Still, to address your concern:

  • the heater filament expands when heated to the point it touches the cathodes. It then becomes part of the cathode and therefore would start emitting electrons;
  • the chipoff coating/insulation cracks weakens the structural integrity of the components. The exposed metal would be emitting more electrons causing that area to burn off faster compared to the coated areas to the point it would have then burn itself a hole;
  • the retrace lines is caused by the same fault. Although there is no increase in the cathode voltages, the electron flow has increased due to the hole, the increase heat (agitation caused by the heater closer to the cathode.
Based on the above, your problem could be cuased by both:
  • the chipoff coating/insulation cracks; and
  • heater filament expanding easily.
Possible solutions may include:
  • improve filament design (make it so that it doesn't expand so much);
  • take into consideration the expansion of the heater filament (reduce its size or increase distance to cathode);
  • reduce heater voltage.
Good luck and thank you for using FixYa.

Posted on Feb 14, 2009

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Welcome to fixya !

The close proximity of cathode and heater and with a insulation crack is surely a recipie for a short and puncture. Try using components without the insulation cracks and try testing the setup. That should confirm our suspicion.

Thanks !

Posted on Feb 14, 2009

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Yes it is the mixture you are useing is causing it you must wait a day or two before before adding and test all between the process. thank you for useing fixya please rate me

Posted on Feb 14, 2009

  • 3 more comments 
  • albert getty
    albert getty Feb 14, 2009

    reheating after main heat is rexpanding and causing your proulbem

  • albert getty
    albert getty Feb 14, 2009

    you need to make a space between coating and medal

  • albert getty
    albert getty Feb 14, 2009

    think of it like this you have two conductors touching you need to keed them apart

  • albert getty
    albert getty Feb 14, 2009

    the black spots are where it is burning do you fill with gas?

  • albert getty
    albert getty Feb 14, 2009

    my first post is a little messed up sorry you must first temper the inside then a day or two later you can put back in to process thank you for useing fixya PLEASE RATE ME ?

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Yes exactly it is because of the shorting up.also check the quality of stuff used.

Posted on Feb 11, 2009

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IF your coating chips off it is exposing a bare metal which would cause you to short out. By this happening when it shorts it burn holes and then you will have puncture holes. Need to try and find a way for the coating to stick on better.

Posted on Feb 11, 2009

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Hi
there is indeed shorting of circuit caused this problem...........

Posted on Feb 11, 2009

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