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Question about ghosting in a video mixer

Author
30 Jul 2007 6:54 PM
hanuman
We have a Panasonic WJ-MX20 video mixer that is ghosting
between A and B. When the slider is moved to one position
or the other there will be faint ghosting at first that will continue
to increase until it looks like a cross-fade between the two.
Moving the slider slightly and in the right way reduces the
ghosting again. Can the problem be corrected by changing
out the slider, and if so where could we get one?

Thanks for any help!
David

Author
30 Jul 2007 7:19 PM
Mike Kujbida
On Jul 30, 2:54 pm, hanuman@dot. wrote:
> We have a Panasonic WJ-MX20 video mixer that is ghosting
> between A and B. When the slider is moved to one position
> or the other there will be faint ghosting at first that will continue
> to increase until it looks like a cross-fade between the two.
> Moving the slider slightly and in the right way reduces the
> ghosting again. Can the problem be corrected by changing
> out the slider, and if so where could we get one?
>
> Thanks for any help!
> David


Assuming you're doing a dissolve from camera 1 to camera 2, this is
what's supposed to happen.
The image from camera 2 is barely nooticeable at first and, as yo
umove the alider, becomes more visible while camera 1's image becomes
fainter until it disappears completely.

Something tells me you're very new at this and need some help.
http://www.internetcampus.com/tvp_ind.htm is a link to a a free
interactive course in studio and field production.

Mike
Author
30 Jul 2007 10:13 PM
hanuman
On Mon, 30 Jul 2007 12:19:14 -0700, Mike Kujbida <kuj***@xplornet.com> wrote:

Show quote
>On Jul 30, 2:54 pm, hanuman@dot. wrote:
>> We have a Panasonic WJ-MX20 video mixer that is ghosting
>> between A and B. When the slider is moved to one position
>> or the other there will be faint ghosting at first that will continue
>> to increase until it looks like a cross-fade between the two.
>> Moving the slider slightly and in the right way reduces the
>> ghosting again. Can the problem be corrected by changing
>> out the slider, and if so where could we get one?
>>
>> Thanks for any help!
>> David
>
>
>Assuming you're doing a dissolve from camera 1 to camera 2, this is
>what's supposed to happen.
>The image from camera 2 is barely nooticeable at first and, as yo
>umove the alider, becomes more visible while camera 1's image becomes
>fainter until it disappears completely.

I'm familiar with the fact that it's supposed to work that way. But
there will always be ghosting even when the slider is all the way
in one position or the other, and it will get stronger by itself until
it looks like a deliberate mix if the slider isn't moved at all and
remains in the same position.

Show quote
>Something tells me you're very new at this and need some help.
>http://www.internetcampus.com/tvp_ind.htm is a link to a a free
>interactive course in studio and field production.
>
>Mike
Author
30 Jul 2007 10:40 PM
Gene E. Bloch
On 7/30/2007, hanuman@dot. posted this:
> We have a Panasonic WJ-MX20 video mixer that is ghosting
> between A and B. When the slider is moved to one position
> or the other there will be faint ghosting at first that will continue
> to increase until it looks like a cross-fade between the two.
> Moving the slider slightly and in the right way reduces the
> ghosting again. Can the problem be corrected by changing
> out the slider, and if so where could we get one?
>
> Thanks for any help!
> David

If the slider is a standard potentiometer, you might be able to buy one
ant any big electronics supplier.

If you don't want to disassemble the unit to find out what the
component is, maybe you can find a repair manual at Panasonic to help
you.

I would worry that the problem is in a different circuit component
connected to the slider, such as a capacitor or transistor, whose
misbehavior is the actual cause of the bad behavior. If you can find an
appropriate slider, changing it out might help to answer that question
;-)

--
Gene E. Bloch (Gino)
letters617blochg3251
(replace the numbers by "at" and "dotcom")
Author
9 Aug 2007 7:36 PM
dh
On Mon, 30 Jul 2007 15:40:24 -0700, Gene E. Bloch <spamfree@nobody.invalid> wrote:

Show quote
>On 7/30/2007, hanuman@dot. posted this:
>> We have a Panasonic WJ-MX20 video mixer that is ghosting
>> between A and B. When the slider is moved to one position
>> or the other there will be faint ghosting at first that will continue
>> to increase until it looks like a cross-fade between the two.
>> Moving the slider slightly and in the right way reduces the
>> ghosting again. Can the problem be corrected by changing
>> out the slider, and if so where could we get one?
>>
>> Thanks for any help!
>> David
>
>If the slider is a standard potentiometer, you might be able to buy one
>ant any big electronics supplier.
>
>If you don't want to disassemble the unit to find out what the
>component is, maybe you can find a repair manual at Panasonic to help
>you.
>
>I would worry that the problem is in a different circuit component
>connected to the slider, such as a capacitor or transistor, whose
>misbehavior is the actual cause of the bad behavior. If you can find an
>appropriate slider, changing it out might help to answer that question
>;-)

    Last week we took it apart and I cleaned the pot with fader
cleaner. A bunch of dirty crap came out of it. Unfortunately my
boss was there and took control, closing it up again before I
got to look for numbers. I didn't even get to finish cleaning the
pot good, but what I did made a huge improvement so maybe
that is the problem. I need to take it apart again when he's
not around, so I can take my time instead of rushing though
as he likes to do. I've emailed Panasonic several times trying
to get them to sell me a pot and the handle that fits on it, but
so far they haven't responded at all.
Author
9 Aug 2007 10:01 PM
Frank
On Thu, 09 Aug 2007 15:36:15 -0400, in 'rec.video.desktop',
in article <Re: Question about ghosting in a video mixer>,
dh@. wrote:

Show quote
>On Mon, 30 Jul 2007 15:40:24 -0700, Gene E. Bloch <spamfree@nobody.invalid> wrote:
>
>>On 7/30/2007, hanuman@dot. posted this:
>>> We have a Panasonic WJ-MX20 video mixer that is ghosting
>>> between A and B. When the slider is moved to one position
>>> or the other there will be faint ghosting at first that will continue
>>> to increase until it looks like a cross-fade between the two.
>>> Moving the slider slightly and in the right way reduces the
>>> ghosting again. Can the problem be corrected by changing
>>> out the slider, and if so where could we get one?
>>>
>>> Thanks for any help!
>>> David
>>
>>If the slider is a standard potentiometer, you might be able to buy one
>>ant any big electronics supplier.
>>
>>If you don't want to disassemble the unit to find out what the
>>component is, maybe you can find a repair manual at Panasonic to help
>>you.
>>
>>I would worry that the problem is in a different circuit component
>>connected to the slider, such as a capacitor or transistor, whose
>>misbehavior is the actual cause of the bad behavior. If you can find an
>>appropriate slider, changing it out might help to answer that question
>>;-)
>
>    Last week we took it apart and I cleaned the pot with fader
>cleaner. A bunch of dirty crap came out of it. Unfortunately my
>boss was there and took control, closing it up again before I
>got to look for numbers. I didn't even get to finish cleaning the
>pot good, but what I did made a huge improvement so maybe
>that is the problem. I need to take it apart again when he's
>not around, so I can take my time instead of rushing though
>as he likes to do. I've emailed Panasonic several times trying
>to get them to sell me a pot and the handle that fits on it, but
>so far they haven't responded at all.

Well, it's good to know that Panasonic isn't any better than JVC at
responding to e-mailed messages. :)

Have you tried Panasonic's online parts ordering Web site? They list
parts for the WJ-MX20.

Parts Ordering
http://www.pasc.panasonic.com/EpartR/PartsListChoice.asp

--
Frank, Independent Consultant, New York, NY
[Please remove 'nojunkmail.' from address to reply via e-mail.]
Read Frank's thoughts on HDV at http://www.humanvalues.net/hdv/
Author
3 Aug 2007 6:21 AM
rcrowley
hanuman wrote:
> We have a Panasonic WJ-MX20 video mixer that is ghosting
> between A and B. When the slider is moved to one position
> or the other there will be faint ghosting at first that will continue
> to increase until it looks like a cross-fade between the two.
> Moving the slider slightly and in the right way reduces the
> ghosting again. Can the problem be corrected by changing
> out the slider, and if so where could we get one?

Recommend trying the contact-cleaner spray that is made
for cleaning switches and potentiometers (such as your slider)
before resorting to replacing the slider.

Replacing the slider could be tricky as there are scores of
different mechanical variations and finding the exact replacement
may not be practical(?)

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