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Conference tekvax::electro_hobby

Title:Electro_Hobby
Notice:TEKVAX may be up-and-down 'till we get settled in..
Moderator:TEKVAX::KOPEC
Created:Thu Jan 15 1987
Last Modified:Tue May 20 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:1831
Total number of notes:14297

1122.0. "TV/cracking sounds/blown fuse" by VAXWRK::KOTHARI () Tue Apr 23 1991 09:45

T.RTitleUserPersonal
Name
DateLines
1122.1A good cleaning first...BSS::D_BANKSDavid Banks -- N�IONTue Apr 23 1991 10:4919
1122.2Re .1VAXWRK::KOTHARITue Apr 23 1991 13:4018
1122.3OPAMP::VMILLERBeen lookin' kinda SCSI latelyTue Apr 23 1991 14:1020
1122.4Sometimes CHASSIS .ne. GROUND :-(BSS::D_BANKSDavid Banks -- N�IONTue Apr 23 1991 15:1917
1122.5New fuse blew up right awayVAXWRK::KOTHARIThu Apr 25 1991 08:3811
1122.6Set cycles on/of in 15min periodsNPSS::WADENetwork Systems SupportWed Feb 19 1997 13:2711
    My ~16 year old Zenith 19" portable runs for about 15-30 minutes then
    gives off a load cracking/snapping sound and the tube goes black. 
    After another 15-30 minutes it comes on fine then the cycle starts
    continues.
    
    This set has certainly given me my $s worth but if anyone has any
    ideas, short of bringing it to a repair shop, I'm game.
    
    Bill
    
     
1122.7Crack in boardENGPTR::MCMAHONWed Feb 19 1997 14:084
    This sounds a lot like what was going on with a 19" that I have. Turned
    out to be a crack in (one of) the circuit board that didn't show up
    until it warmed up and expanded. Took my neighbor a week to track that
    one down.
1122.8CPEEDY::FLEURYThu Feb 20 1997 08:188
    RE: .-1
    
    If you are hearing a snapping sound, then you probably have some arcing
    going on.  Open up the back and look for burn marks either on the board
    or the flyback.  I suspect that the flyback insullation is breaking
    down.  This is not unusual.
    
    Dan
1122.9check for dustCONSLT::ARDUINOThu Feb 20 1997 12:559
    
    If it's this old  ---  check for dust that is causing it to arc. The
    snapping sound is probably the HV (around 27KV) that is causing it.
    If this continues for awhile it will develop a carbon track. This will
    then happen all the time until it completely fails.
    
    good luck,
    //John
    
1122.10try looking for it!ODIXIE::SIMPSONTPC = world's biggest con job!Tue Feb 25 1997 20:106
    Try taking the back off the TV and turning out the room lights.  After
    your eyes adjust to the dark, you might be able to spot it!  
    
    Be careful not to accidently touch the high voltage areas in the dark!!
    
    -Tom
1122.11ATLANT::SCHMIDTSee http://atlant2.zko.dec.com/Tue Feb 25 1997 20:2511
  Please also note that some TVs have some deliberate spark-gaps
  built into them. Generally, they look like thick ceramic cap-
  acitors with a saw-slot cut through the top of them and they're
  often located on the daughter-card that also holds the CRT socket.

  I don't think they should "fire" routinely, but instead are put
  there to prevent arcs that would otherwise occur within the CRT.
  I'd suppose dust-n-crud build-up over time could dramatically
  lower the firing voltage of these spark-gaps, though.

                                   Atlant
1122.12TLE::REAGANAll of this chaos makes perfect senseFri Feb 28 1997 13:367
    Yep, I had a 6 year old Sony XBR that had a similar problem.  Heat
    stress broke a few solder joints on one of the boards.  The repair show
    said they see that quite often (and complained that Sony uses boards that 
    are a little too thin in their opinion).  They resoldered several suspect 
    looking solder joints.  All better now.
    
    				-John
1122.13Wasn't a 27XBR50 by any chance, was it?TLE::INGRAMoopsFri Feb 28 1997 14:310
1122.14TLE::REAGANAll of this chaos makes perfect senseSat Mar 01 1997 10:113
    I was a little older than that... 27XBR15
    
    				-John