Mits CS3535R CRT- TV ringing WHT->BLK transitions

[T o d d P a t t i s t]

I've got a Mitsubishi CS3535R TV. I know they have lots of
capacitor problems, and this is likely one. It let out all
of it's smoke about a year ago and after multiple component
replacements in the power supply and a new vertical chip we
got it running. I expected to buy a new HDTV this year of a
certain size as prices dropped, but just when they got to
where I'm comfortable making the purchase, the wife thinks
one size larger would be just right, which pushes it out of
my price range, so I'm back to fixing this one again.

The problem is that on white to black transitions (say a
white square on the left of the screen) I see strong ringing
to the right of that transition such that the black has gray
bars parallel to the white just to the right of the
transition. There would be perhaps 30-40 bars total across
the screen if the transition were right at the left edge,
but they decay out at about 10 bars.

During the last problem, smoke escaped from a high voltage
cap on the neck yoke. After the other repairs, but before
that cap was tracked down, the set had a similar problem,
except that the ringing was from the horizontal sync pulse
at the left edge and you could see it on entirely black
screens. I don't see anything at the left side of the
screen on black screens now.

I replaced the bad high voltage cap temporarily with one of
questionable reliability (very old) and of course, after the
200 pound set was working, I was too lazy to order a new
cap, pull it down, open it up again and replace that cap.
Does this sound like that cap is my problem? If not, I know
I'm looking at near the video signal pathway, and I know I'm
going to get the ESR meter a good workout, but should I also
look at filter caps for the power to various chips, or is
this likely to be in the signal path?

I really hate the weight of this set, but it looks like it
has to come down at least for a while to fix this.

Thanks for any comments.

 

[David Farber]

I've got a Mitsubishi CS3535R TV. I know they have lots of
capacitor problems, and this is likely one. It let out all
of it's smoke about a year ago and after multiple component
replacements in the power supply and a new vertical chip we
got it running. I expected to buy a new HDTV this year of a
certain size as prices dropped, but just when they got to
where I'm comfortable making the purchase, the wife thinks
one size larger would be just right, which pushes it out of
my price range, so I'm back to fixing this one again.

The problem is that on white to black transitions (say a
white square on the left of the screen) I see strong ringing
to the right of that transition such that the black has gray
bars parallel to the white just to the right of the
transition. There would be perhaps 30-40 bars total across
the screen if the transition were right at the left edge,
but they decay out at about 10 bars.

During the last problem, smoke escaped from a high voltage
cap on the neck yoke. After the other repairs, but before
that cap was tracked down, the set had a similar problem,
except that the ringing was from the horizontal sync pulse
at the left edge and you could see it on entirely black
screens. I don't see anything at the left side of the
screen on black screens now.

I replaced the bad high voltage cap temporarily with one of
questionable reliability (very old) and of course, after the
200 pound set was working, I was too lazy to order a new
cap, pull it down, open it up again and replace that cap.
Does this sound like that cap is my problem? If not, I know
I'm looking at near the video signal pathway, and I know I'm
going to get the ESR meter a good workout, but should I also
look at filter caps for the power to various chips, or is
this likely to be in the signal path?

I really hate the weight of this set, but it looks like it
has to come down at least for a while to fix this.

Thanks for any comments.

Hi Todd,

Even if the capacitors are testing good esr, they can still be leaking onto
the board. So after you're done replacing the high esr caps, you'll need to
give the pc board a good visual inspection as well. Sometimes it's just
easier to heat up the negative side of the electrolytics with a soldering
iron and listen for sizzling noises and that nice fishy aroma. When in
doubt, just replace it. Make sure the board does not have any of the leaking
electrolyte floating around.

Good luck again with this set!

 

[T o d d P a t t i s t]

Even if the capacitors are testing good esr, they can still be leaking onto
the board. So after you're done replacing the high esr caps, you'll need to
give the pc board a good visual inspection as well. Sometimes it's just
easier to heat up the negative side of the electrolytics with a soldering
iron and listen for sizzling noises and that nice fishy aroma. When in
doubt, just replace it. Make sure the board does not have any of the leaking
electrolyte floating around.

Good luck again with this set!

Thanks, David. As you know, this set is a monstrosity and I
really hate to move it. I knew the last time that I'd
probably have to open it again, given the historic problems
with the caps on this set. I think I was just hoping for
someone to post a theory, so I could convince myself it
would be easy, then once I had it down and open, I'd have to
tackle it I was looking at the circuit diagrams you
sent me last year to see where I might start.

Happy Holidays to you.