[TechAssist] Re: thomson vcr,picture shaking,vibrate & no sound.

From: "J Silverman" <greentron@xxxxxxxxxxxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Date: Tue, 12 Feb 2002 12:06:36 -0500
On vcrs where the video head assembly is replacable, with some exceptions,
it is possible to mount the head opposite of the position of the original
head with respect to the azimuth of the actual video pickups.
This creates two problems. First, instead of no guide alignment or just a
minor guide alignment being required, major adjustments are required to get
a good RF envelope with a prerecorded or alignment tape. Second, after
alignment, the chroma subcarrier is 180 degees out of phase with what it
should be so you just get a black and white picture. Any flashes of color
are due to pickup from adjacent video tracks on the tape.
However, if no adjustments are made, the vcrs own new recordings will play
normally on that vcr.
Most video head assemblies have colors or markings that are clues to the
orientation. I usually make a mark on the head assembly and the mounting hub
before removing it so that I can reinstall it or the replacement properly.
Usually, the colors on the head assembly are reproduced on the circuit board
attached to the rotary transformer.
Once in a while, a replacement head assembly is marked incorrectly. In this
case I try reinstalling it reversed 180 degrees before fooling with
adjustments. Also the pickup height can be incorrect if any dirt or foreign
matter is on the mounting seat, which just confuses matters.
These errors were usually immediately obvious on vcrs with manual tracking.
Autotracking creates a whole new set of symptoms if the new head is not
correctly installed. The autotracking should be turned off or defeated when
installing or adjusting a new head.
Jerry Silverman
Greentron Inc
4 Newland Ave
Greenville SC 29609
864 232 3889
Fax 271 2080
mailto:greentron@xxxxxxx
----- Original Message -----
From: "rahman qirat" <rahmanq@xxxxxxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Tuesday, February 12, 2002 10:21 AM
Subject: [TechAssist] Re: thomson vcr,picture shaking,vibrate & no sound.


>
> Jerry & Jeff,can I get explanation " heads are on backwards "
>
>
> >From: "J Silverman" <greentron@xxxxxxxxxxxxxxxx>
> >Reply-To: techassist@xxxxxxxxxxxxx
> >To: <techassist@xxxxxxxxxxxxx>
> >Subject: [TechAssist] Re: thomson vcr,picture shaking,vibrate & no sound.
> >Date: Mon, 11 Feb 2002 15:22:21 -0500
> >
> >
> >Yes
> >Jerry Silverman
> >Greentron Inc
> >4 Newland Ave
> >Greenville SC 29609
> >864 232 3889
> >Fax 271 2080
> >mailto:greentron@xxxxxxx
> >----- Original Message -----
> >From: <MDileo0000@xxxxxxx>
> >To: <techassist@xxxxxxxxxxxxx>
> >Sent: Monday, February 11, 2002 2:35 PM
> >Subject: [TechAssist] Re: thomson vcr,picture shaking,vibrate & no sound.
> >
> >
> > >
> > >  Jerry, you mean the head is 180 degrees off, right?
> > >
> > > Dominic DiLeo
> > > Atlantic TV
> > > Freeport, Maine
> > >
> > >
> > >
> > > In a message dated 2/11/02 2:26:10 PM Eastern Standard Time,
> > > greentron@xxxxxxxxxxxxxxxx writes:
> > >
> > > <<
> > >  My first guess is that the heads are on backwards. If the audio
problem
> >does
> > >  not clear up when the heads are correctly installed and aligned,
check
> >the
> > >  back tension and the tape path at the audio/control head.
> > >  Jerry Silverman
> > >  Greentron Inc
> > >  4 Newland Ave
> > >  Greenville SC 29609
> > >  864 232 3889
> > >  Fax 271 2080
> > >  mailto:greentron@xxxxxxx
> > >  ----- Original Message -----
> > >  From: "rahman qirat" <rahmanq@xxxxxxxxxxx>
> > >  To: <techassist@xxxxxxxxxxxxx>
> > >  Sent: Monday, February 11, 2002 11:38 AM
> > >  Subject: [TechAssist] thomson vcr,picture shaking,vibrate & no sound.
> > >
> > >
> > >  >
> > >  > thomson vcr,vth 22b,made in singapore,used mostly japanese parts.
> > >  > first problem,insert tape,few second than eject back.no play.
> > >  > realightment all gear position,now tape run ok.but picture was
blurr.
> > >  > replace new drum head and play the tape but the picture output is
> >shaking
> > >  > and vibrate and the colour output with sometime black/white then
> >change
> >to
> > >  > colour than few second change back to b/white,on/off.what are the
> >real
> > >  > problem?
> > >  > playback also no sound,if that means the ic la 7282 also faulty?
> > >  >
> > >  > _________________________________________________________________
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> > >  >
> > >   >>
> > >
> > >
> > > Dominic DiLeo
> > > ------------------------------------------
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> > >
> >
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>
>
>
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References:
- [TechAssist] Re: thomson vcr,picture shaking,vibrate & no sound.
  - From: rahman qirat
[TechAssist] Re: thomson vcr,picture shaking,vibrate & no sound.

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