I didn't do the PIP module because in an AP43 main video doesn't go
through it. I've unplugged them with no ill effects, even the PIP
window comes up, without child video of course. (actually IIRC the PIP
worked fine on this set)

Anyway I did change ALL the lytics in the comb filter, first the ones
that checked bad and all of the same value. When the problem persisted
I thought maybe one was leaky (brightness too high seemed to be in line
with that reasoning, maybe), still no good.

I finally got a 2 line comb filter to work. You have to couple the
video from the input to the "YSY" terminal. I used a 10uF cap. Not a
perfect solution, but it was a solution.

Another very interesting thing about this job is that at turn on, the
set has a small white dot slightly below and to the right of the center
of the screen. It goes away as soon as you use any function that
invokes an OSD. It has to be the micro, but I can't hold up the job.

I also had to fix the convergence board, had a crack in it, I replaced
it with one from the boneyard because,,,,, I could. The AP 43 has a
pretty good control set and even full blown convergence only takes me
about 20 minutes, if that.

One thing almost tripped me up, but I was already hip to it, I slide
the chassis in and reconnect the speakers etc., then turn it on. (I had
checked the video input/switching board caps because of the symptom.
I'm sure something on there could possibly cause my original symptom).
I got it in an fired the set up and had interference lines in the
video. Then I realized I hadn't yet strapped up the wires. This was a
case where convergence was deflecting with noise from the SMPS. I
initially thought it was in the video, but moving the convergence
output lines away from the SMPS cured it.

Let that be a word to the wise, when you have a really elusive video
interference problem on an RPTV, take a minute and disable the
convergence. I've had this appear to be a video problem more the once,
the first was an NAP PTV 5 or 600, the last one without digital
comvergence. The PLL of the WF generator chip was not in sync. I've
also seen it on a Zenith (9-1674 based chassis), but this Hitachi
wasn't a hard failure, it was lead dress.

JURB