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2nd Destroyed Green Tube :-(

Discussion in 'Projectors, Screens & Video Processors' started by GagHalfrunt, Dec 3, 2002.

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  1. GagHalfrunt

    GagHalfrunt
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    Whilst I'm waiting for Roland to catch up on his e-mail I wondered if anyone else could shed some light on this:

    I have a Sony 1271QM Projector with previously immaculate tubes except for the Green which kept leaking coolant.

    I replaced the Green tube with another 2nd Hand 07MP tube. The astig rings on the replacement tube were slightly different (they had the older style) so I transferred the rings off the knackered tube onto the replacement.

    That all seemed easy and so did the reinstallation of the tube.

    But! When the projector was powered on the tubes displayed a picture as normal. Then suddenly the Green got brighter and brighter etc until the projector's cut-off circuit cut in.

    I didn't believe it at first so I powered it on a 2nd time. But this time the projector shut down with more of a pop and the tube was destroyed. There is a permanent black dot in the middle of the phosphor. :mad:

    What happened? I've checked it all several times and all seems OK.

    This hobby is starting to get too expensive :(
     
  2. Andre Sveen

    Andre Sveen
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    You proably had scan failure both horisoztal and vertical when you shut it down. Burning the phosfor off the surface.

    Before doing anything more you should find out what caused this. Something electronic I am sure, but what I do not know.

    Wait for Roland. He will give you an answer in depth.
     
  3. Roland @ B4

    Roland @ B4
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    This is not a good story. I'm sorry to say your PJ is toast now. Check the four or is it six coloured cables that plug into the deflection coils they have no keys so it is possible to get these round the wrong way. but if it brought up a correct picture the first time then I would suspect the deflection boards have gone bad. do you get any numbers in the digital display on the side of the projector?

    Didn't get your email by the way.

    On a slightly brighter note VDC are starting to work on the sony tubes. Not sure on the 07MP yet.
     
  4. GagHalfrunt

    GagHalfrunt
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    The Error on the LCD is 04 ...

    According to the Service Manual:
    Abnormal (excessive) current in CRT: The PROTECTOR is activated at above 4.3mA or more of total cathode current. Failure may exist in failed Video OUT transistors (IC101, IC201, IC301) on CARG/CAB boards, damaged CRT, damaged FBT, or too-high setting of G2 (SCREEN) potentiometer.

    I don't see it being the G2 since the tube brightness starts off OK. The Red and Blue tube are fine and stable. The Green does display a picture first. I am also confident that it is wired up correctly as I wrote down the wiring carefully before I took the other tube out.
     
  5. Roland @ B4

    Roland @ B4
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    Bits failing after a tube swap are not uncommon but tacking the tube out is really unfortunete. Run with the burnt tube for the moment. I'm going to send you an amplifier ( tube end stage) which is the bit that provides all the feed back to the projector and could cause the problems you are seeing.

    Can you just clarify what happens now when you power the projector up does the green work? even for just a short while.
     
  6. GagHalfrunt

    GagHalfrunt
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    Roland

    The projector is still operating as described.

    It does power up and the green still displays a white field for about a minute before cutting out.

    Obviously the centre of the phosphor is badly damaged so the centre is now black.

    Many thanks for you patience.
     
  7. Roland @ B4

    Roland @ B4
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    It's odd that it goes for so long before cutting out normally these things are a bit more instant.
     
  8. GagHalfrunt

    GagHalfrunt
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    I must admit I thought the whole thing was odd too.

    The brightness increase is extremely gradual and only affects the green.
     
  9. Roland @ B4

    Roland @ B4
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    How much fluid is left in your leaky green. It might be worth trying that for a short time, provided the coolent covers the displayed area and a bit.
     
  10. GagHalfrunt

    GagHalfrunt
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    Unfortunately it now leaks rather a lot.

    It might be OK to stick it in there for half an hour, just to prove a point.

    How long does it take b4 the tubes fully discharge? I left it for days last time b4 I did it.
     
  11. Roland @ B4

    Roland @ B4
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    All electrics should disipate in about 5mins.
    I always touch the EHT lead to the chasis B4 I grab it just in case.
     
  12. GagHalfrunt

    GagHalfrunt
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    This gets worse :(

    Unfortunately I went to install my "leaky" tube and it's leaked far more liquid whilst it's been sat it Utility Room.

    So it's no good.

    Do you think it's possible that because the old tube was duff that someone has "turned something up" in the projector to compensate which is what caused it to overheat and leak coolant? Which then breaked the replacement tube?

    Or am I talking complete rubbish? ;)
     
  13. GagHalfrunt

    GagHalfrunt
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    Because my projector is knackered we've been watching our films on an old 21" TV with a orange picture.

    Just before christmas the TV's power supply went pop :mad:

    I've now gone down from a 6ft image to a 14 inch TV. Even my friends are taking the mickey.

    Is this the worst CRT sob story? :(
     
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