Because when you smack the set, there is a performance change, this strongly
shows that there has to be a cold solder, or loose connection somewhere.

If you are getting a colour change from smacking the set, then it is
possible that there is a cold solder connection, or a part that is
mechanically loosing contact in the respective signal or control path for
the colour that is having the fault condition. I have also seen on the odd
occasion a CRT going intermittent, and becoming sensitive to being tapped
on.

The quivering is probably a loss of performance in the sync, and or video
processing before the sync takeoff. Many times, in these older sets, the
electrolytic capacitors give problems from going high in ESR, or becoming
thermo sensitive. Using an ESR meter to check the caps would give a very
strong indication to the ones that have failed.

--

Jerry G.
=====

"Mike Holmes" wrote in message
...

I have a JVC 27" early to mid nineties AV-(oops forgot).

It had a vertical collapse problem, and then with help from this group
(especially "Wizard") I fixed that.

Now, it does this thing where it loses blue, except for a dark purple
haze on the extreme left. If you smack it, it will go away and the color
will be prefect, but then the horizontal kinda quivers back and forth,
especially with white edges. Livable but annoying.

I have to assume that whatever the same loose connection or defective
component is controlling both of these behaviors? They do not happen at
the same time.

Inspection/testing of the CRT neck board showed no defective components
and no loose solders (thats where I looked for the color problem)

Jungle IC? ideas?

Thanks alot, Mike