View Single Post
  #1   Report Post  
Jim
 
Posts: n/a
Default How to Adjust the Tape Path Alignment on Newer VCRs

I found it difficult to find simple information on the internet on how
to adjust the tape path alignment. I read books in the library but
they were all about vcrs built in the 80's and early 90's. They were
more complicated than today's vcrs.

First, before you think about aligning the tape path, do a thorough
cleaning of the capstan and rubber pinch roller with isopropyl alcohol
and Q-Tips. May have to clean the capstan a number of times as the
tape oxide can be hard to get off. May have to let it set for awhile.
Also, clean the A/C head, erase head, and any tape guide that has
oxide on it. The tape guides usually stay clean. Don't clean the
cylinder heads as they are self cleaning. Only clean the cylinder
itself if you see oxide build-up but be very careful not to touch the
heads.

Now, you cleaned your vcr but your getting a noise bar at the top or
bottom of the screen still with a known good tape from a known good
vcr. It's time to do a tape path alignment.

Noise is at the Bottom of the Screen:
If the noise is at the bottom of the screen then you need to turn the
take-up roller guide, usually less than 1/4 of a turn. Use the
tracking control on your remote to make the noise show up higher on
the screen. Now turn the roller guide in the direction that moves
that noise down off the screen. (Try not to push down to hard when you
turn the roller guide. You can notch out an old screwdriver or use 2
screwdrivers to turn it.) Adjust tracking again until you see the
noise again. You know when you have adjusted enough when the whole
screen starts to get noisy almost the same time you start seeing the
noise at the bottom of the screen. Now let the vcr auto track (pwr
off/on) and use the tracking control again to check. It should take
about 3 or 4 seconds of holding down the tracking control before you
see the whole screen become noisy. Let the vcr autotrack again and
test the other direction with the tracking control. If you see noise
at the top of the picture well before the whole screen turns noisy,
you need to turn the supply roller guide, see below.

Noise is at the Top of the Screen:
If the noise is at the top of the screen then you need to turn the
supply roller guide, usually less than 1/4 of a turn. Use the
tracking control on your remote to make the noise show up lower on the
screen. Now turn the roller guide in the direction that moves that
noise up off the screen. (Try not to push down to hard when you turn
the roller guide. You can notch out an old screwdriver or use 2
screwdrivers to turn it.) Adjust tracking again until you see the
noise again. You know when you have adjusted enough when the whole
screen starts to get noisy almost the same time you start seeing the
noise at the top of the screen. Now let the vcr auto track (pwr
off/on) and use the tracking control again to check. It should take
about 3 or 4 seconds of holding down the tracking control before you
see the whole screen become noisy.

Slow Motion Tracking - Optional
Not necessary, but here's how you do it. When you hit pause or slow
motion you should not see any noise in your picture. Play the known
good tape and while in slow motion adjust the tracking control to get
the cleanest picture. Now, make a test recording with the vcr you
have been adjusting in 6hr mode. Hit slow motion, but don't use the
tracking control. There should not be any noise in the picture, if
there is noise in the picture, carefully mark the position of the
whole A/C head assembly with a permanent marker. Slightly loosen the
assembly (usually 1 screw to the chassis on newer vcrs) and barely
move it, less than 1/10th inch, one direction or the other until the
noise moves off the screen; retighten screw. If you move too much,
the noise will be gone but the voice will not match the lips (a
multiple of 1/30th second off from the picture). If you move too
much, simply start over from the original marked position.



A/C Head – Azimuth, Tilt, Height, Should not need Adjusting
The A/C head itself is usually ok and should not need adjusting. It
needs adjusting if you turn off HiFi sound and can barely hear any
sound, the tape is getting wrinkled along one edge, or the vcr can not
determine the correct playback speed (2hr, 4hr, 6hr). Basically the
A/C head should be as vertical as possible in both the X & Y axis.
Again, usually it does not need adjusting. Mark screw positions with
a permanent marker.

Azimuth
Azimuth is left and right tilting of the head parallel to the tape
path. (HiFi machines - use the SAP/HiFi on the remote and turn the
HiFi off). With a known good tape adjust the A/C azimuth screw for
loudest possible treble (the screw is usually the farthest screw to
the left or right side of the A/C head). It's ok to turn it quickly
in and out a half turn or so to help you find the loudest sound. A
scene with music is best for making this adjustment. An 1/8 turn can
make a difference in the volume so try to find the best spot.

Tilt
Tilt is forward and backward tilting perpendicular to the tape path.
If tilt is incorrect the tape edge will wrinkle. The tape should be as
vertical as possible over the take-up roller guide, A/C head, and tape
guide next to the capstan. Make sure the tape is not wrinkling
especially at the tape guide by the capstan. You may have to fast
forward and rewind an area of the tape a few times, then eject the
tape and look at the tape edge to see if it is wrinkling. (Basically
the A/C head should be straight up and down, not tilting forward or
backward.) If necessary, fine tune the tilt screw (tilt screw is
usually in front of the head) for best tape movement without wrinkles
- half turn should be enough.

Height
If height is incorrect, the vcr won't be able to determine the correct
tape speed. The tape should be in the middle of the A/C heads. To
raise or lower the height all three screws have to be turned an equal
amount. Too high or too low you will lose motor sync (the vcr can not
determine the correct playback speed (2hr, 4hr, 6hr)). Once you have
motor sync keep adjusting for loudest audio. (HiFi machines - use the
SAP/HiFi on the remote and turn the HiFi off). If you lose track of
your screw positions you can as a last resort tighten all 3 screws and
then back them all out the same amount, about 2 turns. The head
should be vertical again and this will give you a starting point.