Wavy picture at top of screen on dinosaur
Flashoser
I'm not sure about the filter, but it has to do with the Sync of the VCR
with the TV, it happens all the time with a newer VCR and an older TV, SAM
might have the Official Name for this, I just tell people that, cause as
far as I know there is nothing you can do about it..
I forgot what you call it..
How about it SAM?, what is that called?
Michael Walker ( Poke, Prod & Hope, that's my Moto! )
Video Speicialties
Chippewa Falls, WI
s.rodyn
Its called FLAGING...
Sam Goldwasser
> I'm not sure about the filter, but it has to do with the Sync of the VCR
> with the TV, it happens all the time with a newer VCR and an older TV, SAM
> might have the Official Name for this, I just tell people that, cause as
> far as I know there is nothing you can do about it..
> I forgot what you call it..
Flag waving?
The older TVs could not lock the H-sync fast enough following beginning
of scan. Thus, if the VCR was not adjusted to the same back tension as
the recording VCR or the video head chip alignment was slightly off,
this behavior would result. There may have been mods to some TVs but
in general, not. If it is your VCR that is not adjusted properly, that
may be fixable. See the sections in the FAQ on flag waving and back tension.
If you are referring to a problem with Macrovision copy protection, that is
a separate issue.
--- sam : Sci.Electronics.Repair FAQ: http://www.paranoia.com/~filipg/REPAIR/
Coming soon to a computer screen near you: http://www.repairfaq.org/
Joseph E. Fealkovich
In <338ED5...@ix.netcom.com> "s.rodyn" <s.r...@ix.netcom.com>
writes:
>Flashoser wrote:
>>
>> I'm not sure about the filter, but it has to do with the Sync of the
VCR
>> with the TV, it happens all the time with a newer VCR and an older
TV, SAM
>> might have the Official Name for this, I just tell people that,
cause as
>> far as I know there is nothing you can do about it..
>>
>> I forgot what you call it..
>>
>>
>> Michael Walker ( Poke, Prod & Hope, that's my Moto! )
>> Video Speicialties
>> Chippewa Falls, WI
>
>Its called FLAGING...
S.rodyn and others, I call it simply the "hook". It is caused by the
slowness of the time constant in the person's old television to
compensate for videotape's natural timebase errors. In other words, a
VCR does not put out as stable horizontal timebase as an off the air
signal. The horizontal oscillator's phase and frequency correction
circuitry in an older TV is too slow to correct the horiz oscillator's
frequency on a VCR signal, due to it's instability compared with an off
the air signal, and it will cause the oscillator to slightly drift,
especially when the heads switch on the VCR during (actually 21 lines
before) the vertical sync. There is a very tiny burst of noise during
video head switch, that will also throw the horizontal oscillator for a
loop. That causes flagging, or the "hook" at the top of the picture.
Ever wonder why MTS stereo VCR's don't output stereo sound at the VCR's
RF output jacks? It is not a problem to remodulate the stereo signal,
but MTS VCR's use a pilot signal at the horizontal frequency, and the
VCR's natural horiz frequency errors would drive the MTS circuitry
totally nuts. TV stations use videotape a lot, but everything goes thru
a TBC, (Time Base Corrector), before being transmitted. Yes, even those
nice U-matic and 1" machines have timebase errors too. I hope this
helps all, please be good and take care!:)
Joe at jef...@ix.netcom.com
Clifton T. Sharp, Jr.
Joseph E. Fealkovich wrote:
> S.rodyn and others, I call it simply the "hook". It is caused by the
> slowness of the time constant in the person's old television to
> compensate for videotape's natural timebase errors. In other words, a
> VCR does not put out as stable horizontal timebase as an off the air
> signal. The horizontal oscillator's phase and frequency correction
> circuitry in an older TV is too slow to correct the horiz oscillator's
> frequency on a VCR signal, due to it's instability compared with an off
> the air signal, and it will cause the oscillator to slightly drift,
> especially when the heads switch on the VCR during (actually 21 lines
> before) the vertical sync. There is a very tiny burst of noise during
> video head switch, that will also throw the horizontal oscillator for a
> loop. That causes flagging, or the "hook" at the top of the picture.
I disagree. I fixed the hooking/flagging problem in my brother's 1970's
Zenith by slowing some time constant in the horizontal AGC circuitry;
I changed an electrolytic to a considerably higher value. And it wasn't
so much the age of the set as the particular design; Zeniths were the
worst offenders with this problem back when home VCRs were new. (And yet
back then they were about the best sets on the market.)
--
+---------------------------------------------------------------------------+
| Cliff Sharp | If tin whistles are made of tin, what do they make |
| WA9PDM | foghorns out of? --Lonnie Donegan |
+---------------------------------------------------------------------------+
Raymond Carlsen
> It is caused by the slowness of the time constant in the person's old
> television to compensate for videotape's natural timebase errors. In
> other words, a VCR does not put out as stable horizontal timebase as an
> off the air signal.
I would like to add something here. Several followup posters mentioned
that the greater error on the screen when playing pre-recorded tapes is
because of the copyguard garbage. The real reason is that the time-base
error of a tape playing on a different VCR than the one that recorded it is
greater. Mechanical differences in machines contribute to the normal timing
errors produced by all VCRs. Other factors include differences in
temperature, humidity, age of tape since recording, how tightly it's wound
on the reel etc. Plastic tape is marvelous stuff, but it's a bit like
recording on a rubber band.
I'll bet if the original poster recorded a tape on his own machine and
played it back, the picture would bend very little even on his old TV. If
he then borrowed a tape from someone else who recorded it on their VCR, it
would "flag" as much as any pre-recorded tape from the video store...
copyguard or not. This was true back when Beta was popular, copyguard was
different, and many TV sets were not up to the challange of "rubber"
horizontal sync.
Ray Carlsen
CARLSEN ELECTRONICS... a leader in trailing-edge technology.