On Jan 18, 11:49*am, "N_Cook" wrote:
Lip* wrote in message

...


Could be as simple (to diagnose ,not necessarily to rectify) as a switch *or
board interconnect corrossion problem , try waggling/pulling/pushing them


Thank you for the tip.
Tonight I will open the scope and try to replug everything possible.

I was looking at the schematics, and realize the horizontal sweep
output amplifiers (Q789 and Q779, two PNP transistors) depend on
+100V. The +100V power supply is just a full wave rectifiers from a
center tap secondary (from the switching power supply), filtered by a
single 33uF (C954). If this cap is bad or going bad, hell may appear
at the horizontal sweep.

But, I remember the problem started at the right half of the sweep on
screen, while the left was working nice. When I saw it happening,
immediately suspected about the amplifier of the CRT plate that
controls the right side.

If the +100V was bad, the problem would not appear only at the right
side.

Right now, the problem appears both sides simultaneously.

At the schematics, page [6], scope points 34 and 35 is the output of
the horizontal sweep chip, respectively left and right, that will
drive the output transistors. May be I could scope (I have other
scope, a 2246) those points and see if anything different is
happening.

Of course, there is a connector from those points to the output
amplifiers... may be your are right, some bad connection in there, may
be a simple replug will fix it. This scope was stored vertically in
my room, and from time to time it was moved a little bit to the right,
left, under a desk, etc. This moving vibration (dragging the back
feet in the floor) may cause some bad contacts.

I will report any news.

Thanks again for the tip.

Wagner