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From: Ippei Okamura on 15 Jun 2010 15:09
Hello,

I have Sony PVM-2950 with pincushion problem.
The image bows toward the center of the screen from both top and
bottom. I believe this symptom is called "horizontal" or "north-
south" pincushion problem.
I tired to adjust it in service mode, but I was unable to control the
amount of bowing at top and bottom of the screen. I can control
barrel shaped pincushion (east-west) but it does nothing on top and
bottom of the screen.

Is there anything that I can adjust horizontal pincushion without
opening the set?
Could somebody please give me a clue on what is causing this problem
and where and what to look for?
I have a service manual but because I am not an expert, only thing I
can think of is some failure in VC, DX, or part of A board.

This is first time I'm posting, so please let me know if I'm doing
something wrong.
I would appreciate any response..
From: Meat Plow on 15 Jun 2010 17:13
On Tue, 15 Jun 2010 12:09:45 -0700, Ippei Okamura ǝʇoɹʍ:

> Hello,
>
> I have Sony PVM-2950 with pincushion problem. The image bows toward the
> center of the screen from both top and bottom. I believe this symptom
> is called "horizontal" or "north- south" pincushion problem.
> I tired to adjust it in service mode, but I was unable to control the
> amount of bowing at top and bottom of the screen. I can control barrel
> shaped pincushion (east-west) but it does nothing on top and bottom of
> the screen.
>
> Is there anything that I can adjust horizontal pincushion without
> opening the set?
> Could somebody please give me a clue on what is causing this problem and
> where and what to look for?
> I have a service manual but because I am not an expert, only thing I can
> think of is some failure in VC, DX, or part of A board.
>
> This is first time I'm posting, so please let me know if I'm doing
> something wrong.
> I would appreciate any response..

I've read somewhere those things have a hidden Optimode test pattern in
the service mode usefull for pincushion and convergence. But I have no
idea how to access it.
From: Ippei Okamura on 15 Jun 2010 21:51
On Jun 15, 4:13 pm, Meat Plow <mhyw...(a)yahoo.com> wrote:
> On Tue, 15 Jun 2010 12:09:45 -0700, Ippei Okamura ǝʇoɹʍ:
>
>
>
> > Hello,
>
> > I have Sony PVM-2950 with pincushion problem. The image bows toward the
> > center of the screen from both top and bottom.  I believe this symptom
> > is called "horizontal" or "north- south" pincushion problem.
> > I tired to adjust it in service mode, but I was unable to control the
> > amount of bowing at top and bottom of the screen.  I can control barrel
> > shaped pincushion (east-west) but it does nothing on top and bottom of
> > the screen.
>
> > Is there anything that I can adjust horizontal pincushion without
> > opening the set?
> > Could somebody please give me a clue on what is causing this problem and
> > where and what to look for?
> > I have a service manual but because I am not an expert, only thing I can
> > think of is some failure in VC, DX, or part of A board.
>
> > This is first time I'm posting, so please let me know if I'm doing
> > something wrong.
> > I would appreciate any response..
>
> I've read somewhere those things have a hidden Optimode test pattern in
> the service mode usefull for pincushion and convergence. But I have no
> idea how to access it.

Thank you for reply!

Yes, if it can generate such pattern by itself, it would be really
helpful.
I heard that Sony BVM series can generate cross-hatch by itself but
that series is for mastering at broadcast stations and might cost
triple of PVM series.
From: Ippei Okamura on 15 Jun 2010 23:01
Just to clarify, the following is the drawing of the symptom:
_________________________
| \ / |
| \ / |
| +__________________+ | @
| |
| |
| |
| |
| +------------------------------+ | @
| / \ |
| / \ |
--------------------------------------------

@: in reality, these lines follow smooth curve towards center of
screen.


I'm starting to get confused with terms "horizontal pincushion" and
"vertical pincushion"...
But I believe that the symptom shown above is called "north-south
pincushion".

The article "TV and Monitor Deflection Systems" by Samuel M.
Goldwasser (http://www.repairfaq.org/sam/deflfaq.htm) is very
helpful.
In this article, I found that north-south pincushion is difficult to
handle and it is better to design deflection coil so that "the picture
tube needs no active N/S correction" (http://www.repairfaq.org/sam/
deflfaq.htm#dsdns).

I'm starting think that PVM-2950 has special circuit that corrects
north-south pincushion.. (??)
From: Ippei Okamura on 16 Jun 2010 14:41
I took some pictures:
http://picasaweb.google.com/117475674374880339742/PVM2950Q?feat=directlink

I tried adjusting in service mode. I was able to fill up the entire
screen with image but bowing doesn't go away. I noticed that "H TRPZ"
has very little effect on the screen.

Any comments or suggestion will be greatly appreciated.
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