I have a Viewsonic PT813 monitor (21" CRT) that is almost 10 years old.
It has been a great monitor but has started developing a problem. I
have searched the newsgroups and it sounds a lot like a flyback
problem, but I thought I would post the symptoms and see if anybody has
experienced this. Over the past few months while the monitor is on
there would periodically be a very load snap and the screen would go
black, then come right back on. This occured maybe once every two
weeks. Now when I turn the monitor off, I hear the normal static
electricity crackle sound but also a distinct snap, pause, snap, pause,
snap. Whenever I turn the monitor on, (in addition to the normal
sounds it always made) I hear a distinct snap-snap-snap. Also if the
room is dark I can sometimes see a white glow on the screen that looks
like a snowball hitting a solid wall in random places. The appearance
of these "hits" coincides with the snap-snap-snap sound. I've taken
the case apart and blew out all the dust but I cannot see any arcing or
anything out of the ordinary. Also, the snap sound seems to be coming
from the flyback. Anybody have any thoughts? Is it the flyback or
could it be something else? The monitor is fine otherwise, but is this
an expensive fix and where would I even get the parts? Thanks!

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I have a Viewsonic PT813 monitor (21" CRT) that is almost 10 years old.
It has been a great monitor but has started developing a problem. I
have searched the newsgroups and it sounds a lot like a flyback
problem, but I thought I would post the symptoms and see if anybody has
experienced this. Over the past few months while the monitor is on
there would periodically be a very load snap and the screen would go
black, then come right back on. This occured maybe once every two
weeks. Now when I turn the monitor off, I hear the normal static
electricity crackle sound but also a distinct snap, pause, snap, pause,
snap. Whenever I turn the monitor on, (in addition to the normal
sounds it always made) I hear a distinct snap-snap-snap. Also if the
room is dark I can sometimes see a white glow on the screen that looks
like a snowball hitting a solid wall in random places. The appearance
of these "hits" coincides with the snap-snap-snap sound. I've taken
the case apart and blew out all the dust but I cannot see any arcing or
anything out of the ordinary. Also, the snap sound seems to be coming
from the flyback. Anybody have any thoughts? Is it the flyback or
could it be something else? The monitor is fine otherwise, but is this
an expensive fix and where would I even get the parts? Thanks!


Sometimes the outer casing of the flyback transformer breaks down allowing
the EHT to crack over to any adjacent part of the chassis, but if you've
taken the back off and watched in low light you'd almost certainly see the
spark!

Another thing you could check is the focus lead spark gap in the CRT base
connector, after 10 yrs a build up of dust would be no surprise - I've even
known spiders and various other creepy crawlies to get into these spark
gaps!