Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

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bg
 
Posts: n/a
Default Fisher cassette heads

The heads from left to right are, the erase head, the record head and the
playback head. Any cassette I've ever seen has a guide attached to the
playback head. If possible, bend the damaged guide back into place. Usually
this guide is spot welded, therefore the height of the guide might not have
changed. This guide sets the tracking which usually is not adjustable
because the guide is fixed to the playback head at the factory. On rare
occasions this guide is adjustable.
The tilt of the head sets azimuth which is adjustable on all decks. You will
have to examine the record and playback heads to see if there is azimuth
adjustments for both heads. I would expect there is. Head height raises or
lowers the position of the head gaps on the tape. Azimuth rotates the gaps
so that they are aligned perpendicular (90 degrees) to the tape. Azimuth
will have a slight effect on the head height. Another head adjustment you
might have is zenith. Usually located at the rear of the head, it tilts the
face of the head, so that the head is parallel to the tape. This adjustment
if incorrect, would tilt the top of the head either closer or further from
the tape than the bottom of the head. It causes uneven head wear and it
causes the tape to scew up and down. As the tape scews, the azimuth and
tracking will also be out of adjustment. The erase head should also have a
non adjustable guide affixed to it.
Check to see that you have these guides in place, the azimuth and zenith
adjustments, and that the adjustments will move the heads. If you can't
physically align the heads, or the guides are bad, there is no sense in
going any further. you will have to replace whatever mechanics are bad.
You might want to sacrafice an old cassette by cutting away the plastic
shell in the area where the heads contact the tape. This will give you the
abiltiy to see how the tape rides over the heads. If the tape is visibly
moving up or down, you will have to correct this. It is impossible to align
a head to tape that moves all over the place. The basic concept is to set
all guides at the same height so that the tape enters the shell and leaves
the shell at the same height. Any guides in between should not raise or
lower the tape as it travels thru the shell.
Post back here with your results and we'll determine the next step.
bg


Marko wrote in message ...
BG: I thought I would check for replies just one more time before I

stopped
NG activity for awhile. Glad I did.


I have a signal generator, alignment tape, scope, and HP5210 freq meter

that
I have used to set the motor RPM with 1KHz test tone.

I haven't checked yet, but I am hoping that

(1) the head on the far right is the play head
(2) the tape monitor switch will allow me to record a test tone (I will use
10KHz) and then monitor it with the play head so that I can align the

record
head.
(3) that the tape guide on the PB head (which has been bent out of the tape
path) is not necessary for proper tape transfer over the heads.

What worries me is that the tape guide is on the record head and I must
align the playback head first.

I didn't notice the third head at first and aligned the playback with the
record head adjustment screw. This worked because the tape guide is on the
record head.

How do I start out with proper alignment of the two tape guides before
aligning the heads? One guide, the first one, is affixed to the transport
frame and the second guide is affixed to the record head. I think this
problem may have been encountered by
whoever worked on it before it was sent to a resale shop. I could see that
they had disturbed the paint on the screws. It also had two stretched

belts
and a very dirty rec/play switch on the board, so I'm not sure. The belts
may have stretched and the grease in the switch may have dried from sitting
on the shelf for years after they encountered the alignment problem.

What do you suggest? Sincerely, Mark (this is a top post)






----- Original Message -----
From: "bg"
Newsgroups: sci.electronics.repair
Sent: Sunday, July 27, 2003 11:46 PM
Subject: Fisher cassette heads


You need an audio generator, and an AC audio voltmeter with a DB scale.

If
you have this equipment I'll steer you through it.
bg
Marko wrote in message ...
I have a Fisher cassette deck with separate record and playback heads.

I
assume that the one in the middle, the large one, is the record head.

I have a professional alignment tape. How does one align the record

head?
There is a tape monitor switch which probably is used to compare input

to
output.

These are ferrite heads with no visible wear, new belts, switches

cleaned
thoroughly: this deck is worth an alignment as opposed to the trash can
(mabey).

Also, one tape guide (the one on the far left, just to the left of the
record head) is affixed to the transport frame. The second guide is

affixed
to the record head. The third tape guide on the playback head is bent

over
to the side, obviously bent intentionally to get it out of the way. The
adjustment screw to this bent guide is not accessable for adjustment

(sloppy
design). The third tape guide is probably not necessary since it is

only
about a cm from the guide on the record head. This transport may be a

piece
of junk due to lousy design.

Any helpful hints will be appreciated Thanks, Mark





"bg" wrote in message
...
You need an audio generator, and an AC audio voltmeter with a DB scale.

If
you have this equipment I'll steer you through it.
bg
Marko wrote in message ...
I have a Fisher cassette deck with separate record and playback heads.

I
assume that the one in the middle, the large one, is the record head.

I have a professional alignment tape. How does one align the record

head?
There is a tape monitor switch which probably is used to compare input

to
output.

These are ferrite heads with no visible wear, new belts, switches

cleaned
thoroughly: this deck is worth an alignment as opposed to the trash can
(mabey).

Also, one tape guide (the one on the far left, just to the left of the
record head) is affixed to the transport frame. The second guide is

affixed
to the record head. The third tape guide on the playback head is bent

over
to the side, obviously bent intentionally to get it out of the way. The
adjustment screw to this bent guide is not accessable for adjustment

(sloppy
design). The third tape guide is probably not necessary since it is

only
about a cm from the guide on the record head. This transport may be a

piece
of junk due to lousy design.

Any helpful hints will be appreciated Thanks, Mark








  #2   Report Post  
Marko
 
Posts: n/a
Default Fisher cassette heads


"bg" wrote in message
...
The heads from left to right are, the erase head, the record head and the
playback head. Any cassette I've ever seen has a guide attached to the
playback head.


The guide attached to the PB head is fine. It is the one on the Rec head
that is bent. It is ruined. It was affixed to the R-head with a screw and
enamel. It came loose and is impossible to align. The head must be removed
to tighten the screw and adjustment is not possible when head is remounted.

The deck appears to be technology without due design consideration.


If possible, bend the damaged guide back into place. Usually
this guide is spot welded, therefore the height of the guide might not

have
changed. This guide sets the tracking which usually is not adjustable
because the guide is fixed to the playback head at the factory. On rare
occasions this guide is adjustable.
The tilt of the head sets azimuth which is adjustable on all decks.


As with every other deck i have seen, which are all single motor low end
decks, only the azimuth is adjustable with the typical screw and spring set
up.

You will
have to examine the record and playback heads to see if there is azimuth
adjustments for both heads.


yes, there is also azimuth for the record head

I would expect there is. Head height raises or
lowers the position of the head gaps on the tape.


I will look again to see if there is a height adj

Azimuth rotates the gaps
so that they are aligned perpendicular (90 degrees) to the tape.


I understand

Azimuth
will have a slight effect on the head height. Another head adjustment you
might have is zenith. Usually located at the rear of the head, it tilts

the
face of the head, so that the head is parallel to the tape.


I'll check, I have never noticed this

This adjustment
if incorrect, would tilt the top of the head either closer or further from
the tape than the bottom of the head. It causes uneven head wear and it
causes the tape to scew up and down. As the tape scews, the azimuth and
tracking will also be out of adjustment. The erase head should also have a
non adjustable guide affixed to it.


Yes, it does


Check to see that you have these guides in place, the azimuth and zenith
adjustments, and that the adjustments will move the heads.


It looks to me that the zenith is set with the azimuth screw. There is some
travel in the slot that allows rotation of the head.

If you can't
physically align the heads, or the guides are bad, there is no sense in
going any further. you will have to replace whatever mechanics are bad.
You might want to sacrafice an old cassette by cutting away the plastic
shell in the area where the heads contact the tape. This will give you the
abiltiy to see how the tape rides over the heads.


I will look into it

If the tape is visibly
moving up or down, you will have to correct this. It is impossible to

align
a head to tape that moves all over the place. The basic concept is to set
all guides at the same height so that the tape enters the shell and

leaves
the shell at the same height.


Makes sense

Any guides in between should not raise or
lower the tape as it travels thru the shell.
Post back here with your results and we'll determine the next step.


Thanks BG. I have several projects like this. This one will have to sit
awhile until its' time comes. I wanted to look into it now so I could plan
what to do.

If you will send me your e-mail address to I will get back to
you when I get these other projects out of the way.

Sincerely, Mark
bg


Marko wrote in message ...
BG: I thought I would check for replies just one more time before I

stopped
NG activity for awhile. Glad I did.


I have a signal generator, alignment tape, scope, and HP5210 freq meter

that
I have used to set the motor RPM with 1KHz test tone.

I haven't checked yet, but I am hoping that

(1) the head on the far right is the play head
(2) the tape monitor switch will allow me to record a test tone (I will

use
10KHz) and then monitor it with the play head so that I can align the

record
head.
(3) that the tape guide on the PB head (which has been bent out of the

tape
path) is not necessary for proper tape transfer over the heads.

What worries me is that the tape guide is on the record head and I must
align the playback head first.

I didn't notice the third head at first and aligned the playback with the
record head adjustment screw. This worked because the tape guide is on

the
record head.

How do I start out with proper alignment of the two tape guides before
aligning the heads? One guide, the first one, is affixed to the

transport
frame and the second guide is affixed to the record head. I think this
problem may have been encountered by
whoever worked on it before it was sent to a resale shop. I could see

that
they had disturbed the paint on the screws. It also had two stretched

belts
and a very dirty rec/play switch on the board, so I'm not sure. The

belts
may have stretched and the grease in the switch may have dried from

sitting
on the shelf for years after they encountered the alignment problem.

What do you suggest? Sincerely, Mark (this is a top post)






----- Original Message -----
From: "bg"
Newsgroups: sci.electronics.repair
Sent: Sunday, July 27, 2003 11:46 PM
Subject: Fisher cassette heads


You need an audio generator, and an AC audio voltmeter with a DB

scale.
If
you have this equipment I'll steer you through it.
bg
Marko wrote in message ...
I have a Fisher cassette deck with separate record and playback heads.

I
assume that the one in the middle, the large one, is the record head.

I have a professional alignment tape. How does one align the record

head?
There is a tape monitor switch which probably is used to compare input

to
output.

These are ferrite heads with no visible wear, new belts, switches

cleaned
thoroughly: this deck is worth an alignment as opposed to the trash

can
(mabey).

Also, one tape guide (the one on the far left, just to the left of the
record head) is affixed to the transport frame. The second guide is
affixed
to the record head. The third tape guide on the playback head is bent

over
to the side, obviously bent intentionally to get it out of the way.

The
adjustment screw to this bent guide is not accessable for adjustment
(sloppy
design). The third tape guide is probably not necessary since it is

only
about a cm from the guide on the record head. This transport may be a
piece
of junk due to lousy design.

Any helpful hints will be appreciated Thanks, Mark





"bg" wrote in message
...
You need an audio generator, and an AC audio voltmeter with a DB

scale.
If
you have this equipment I'll steer you through it.
bg
Marko wrote in message ...
I have a Fisher cassette deck with separate record and playback heads.

I
assume that the one in the middle, the large one, is the record head.

I have a professional alignment tape. How does one align the record

head?
There is a tape monitor switch which probably is used to compare input

to
output.

These are ferrite heads with no visible wear, new belts, switches

cleaned
thoroughly: this deck is worth an alignment as opposed to the trash

can
(mabey).

Also, one tape guide (the one on the far left, just to the left of the
record head) is affixed to the transport frame. The second guide is
affixed
to the record head. The third tape guide on the playback head is bent

over
to the side, obviously bent intentionally to get it out of the way.

The
adjustment screw to this bent guide is not accessable for adjustment
(sloppy
design). The third tape guide is probably not necessary since it is

only
about a cm from the guide on the record head. This transport may be a
piece
of junk due to lousy design.

Any helpful hints will be appreciated Thanks, Mark










  #3   Report Post  
Marko
 
Posts: n/a
Default Fisher cassette heads

BG: I have reread your post several times and now realize that without the
guide on the PB head then it is up to me and luck to get it going right.

Unless you have some more advice, thanks much, you've been a great help.
Sincerely, Mark

"bg" wrote in message
...
The heads from left to right are, the erase head, the record head and the
playback head. Any cassette I've ever seen has a guide attached to the
playback head. If possible, bend the damaged guide back into place.

Usually
this guide is spot welded, therefore the height of the guide might not

have
changed. This guide sets the tracking which usually is not adjustable
because the guide is fixed to the playback head at the factory. On rare
occasions this guide is adjustable.
The tilt of the head sets azimuth which is adjustable on all decks. You

will
have to examine the record and playback heads to see if there is azimuth
adjustments for both heads. I would expect there is. Head height raises or
lowers the position of the head gaps on the tape. Azimuth rotates the gaps
so that they are aligned perpendicular (90 degrees) to the tape. Azimuth
will have a slight effect on the head height. Another head adjustment you
might have is zenith. Usually located at the rear of the head, it tilts

the
face of the head, so that the head is parallel to the tape. This

adjustment
if incorrect, would tilt the top of the head either closer or further from
the tape than the bottom of the head. It causes uneven head wear and it
causes the tape to scew up and down. As the tape scews, the azimuth and
tracking will also be out of adjustment. The erase head should also have a
non adjustable guide affixed to it.
Check to see that you have these guides in place, the azimuth and zenith
adjustments, and that the adjustments will move the heads. If you can't
physically align the heads, or the guides are bad, there is no sense in
going any further. you will have to replace whatever mechanics are bad.
You might want to sacrafice an old cassette by cutting away the plastic
shell in the area where the heads contact the tape. This will give you the
abiltiy to see how the tape rides over the heads. If the tape is visibly
moving up or down, you will have to correct this. It is impossible to

align
a head to tape that moves all over the place. The basic concept is to set
all guides at the same height so that the tape enters the shell and

leaves
the shell at the same height. Any guides in between should not raise or
lower the tape as it travels thru the shell.
Post back here with your results and we'll determine the next step.
bg


Marko wrote in message ...
BG: I thought I would check for replies just one more time before I

stopped
NG activity for awhile. Glad I did.


I have a signal generator, alignment tape, scope, and HP5210 freq meter

that
I have used to set the motor RPM with 1KHz test tone.

I haven't checked yet, but I am hoping that

(1) the head on the far right is the play head
(2) the tape monitor switch will allow me to record a test tone (I will

use
10KHz) and then monitor it with the play head so that I can align the

record
head.
(3) that the tape guide on the PB head (which has been bent out of the

tape
path) is not necessary for proper tape transfer over the heads.

What worries me is that the tape guide is on the record head and I must
align the playback head first.

I didn't notice the third head at first and aligned the playback with the
record head adjustment screw. This worked because the tape guide is on

the
record head.

How do I start out with proper alignment of the two tape guides before
aligning the heads? One guide, the first one, is affixed to the

transport
frame and the second guide is affixed to the record head. I think this
problem may have been encountered by
whoever worked on it before it was sent to a resale shop. I could see

that
they had disturbed the paint on the screws. It also had two stretched

belts
and a very dirty rec/play switch on the board, so I'm not sure. The

belts
may have stretched and the grease in the switch may have dried from

sitting
on the shelf for years after they encountered the alignment problem.

What do you suggest? Sincerely, Mark (this is a top post)






----- Original Message -----
From: "bg"
Newsgroups: sci.electronics.repair
Sent: Sunday, July 27, 2003 11:46 PM
Subject: Fisher cassette heads


You need an audio generator, and an AC audio voltmeter with a DB

scale.
If
you have this equipment I'll steer you through it.
bg
Marko wrote in message ...
I have a Fisher cassette deck with separate record and playback heads.

I
assume that the one in the middle, the large one, is the record head.

I have a professional alignment tape. How does one align the record

head?
There is a tape monitor switch which probably is used to compare input

to
output.

These are ferrite heads with no visible wear, new belts, switches

cleaned
thoroughly: this deck is worth an alignment as opposed to the trash

can
(mabey).

Also, one tape guide (the one on the far left, just to the left of the
record head) is affixed to the transport frame. The second guide is
affixed
to the record head. The third tape guide on the playback head is bent

over
to the side, obviously bent intentionally to get it out of the way.

The
adjustment screw to this bent guide is not accessable for adjustment
(sloppy
design). The third tape guide is probably not necessary since it is

only
about a cm from the guide on the record head. This transport may be a
piece
of junk due to lousy design.

Any helpful hints will be appreciated Thanks, Mark





"bg" wrote in message
...
You need an audio generator, and an AC audio voltmeter with a DB

scale.
If
you have this equipment I'll steer you through it.
bg
Marko wrote in message ...
I have a Fisher cassette deck with separate record and playback heads.

I
assume that the one in the middle, the large one, is the record head.

I have a professional alignment tape. How does one align the record

head?
There is a tape monitor switch which probably is used to compare input

to
output.

These are ferrite heads with no visible wear, new belts, switches

cleaned
thoroughly: this deck is worth an alignment as opposed to the trash

can
(mabey).

Also, one tape guide (the one on the far left, just to the left of the
record head) is affixed to the transport frame. The second guide is
affixed
to the record head. The third tape guide on the playback head is bent

over
to the side, obviously bent intentionally to get it out of the way.

The
adjustment screw to this bent guide is not accessable for adjustment
(sloppy
design). The third tape guide is probably not necessary since it is

only
about a cm from the guide on the record head. This transport may be a
piece
of junk due to lousy design.

Any helpful hints will be appreciated Thanks, Mark










  #4   Report Post  
Marko
 
Posts: n/a
Default Fisher cassette heads

BG: OK let's give it a try. This time I will get it right about where the
guides are

Originally this machine had four guides:
(1) one solidly affixed to left of erase head
(2) one on left of record head, but affixed to the transport frame
(3) One spot welded to the right side of the record head
(4) One affixed (with miniature screw) to left side of PB head

The one on the right side of the record head is less than a cm from the
guide on the left of the PB head (PB head guide is effectively missing, not
repairable, mangled)

As far as stability of the tape going across the heads goes, I feel that
the 3 remaining guides will be enough, if they are aligned

The two problems are as follows:

(1) The guide to the left of the record head is affixed to frame and all
other guides must correspond to this one or the tape will not ride smoothly
on the heads.

(2) Seems like the guide to the right of the record head should not effect
the path of the tape over the PB head because it is over the screw that is
not for adjustment (the mounting screw that is tightened and not
adjustable). BUT, it does because I didn't notice the 3rd head when I was
adjusting the azimuth for the record head (I thought it was the playback
head at the time). Turning the azimuth adjustment for the record head
affects the path of the tape over the PB head. I recall seeing the PB
amplitude vary on a scope as the azimuth screw for Rec head was turned.

I hope I have written this in a readable manner.

All I can see is that I should adjust the Rec and PB heads over and over
until hopefully they are aligned.

Any ideas or warnings, BG? Thanks for your help. Your advice has given me
a much needed understanding of this situation. Mark
"bg" wrote in message
...
Just about every deck I've ever seen has a guide on the ingoing side of

the
erase head and a guide on the outgoing side of the playback head, with no
other guides in between. It is also common practise to affix the guides to
the heads, not the chassis. On the chassis there will be posts that hold
the shell in place, they are not tape guides.
I have plenty of time . If you are ready to continue let me know
bg
Marko wrote in message ...
BG: I have reread your post several times and now realize that without

the
guide on the PB head then it is up to me and luck to get it going right.

Unless you have some more advice, thanks much, you've been a great help.
Sincerely, Mark

"bg" wrote in message
...
The heads from left to right are, the erase head, the record head and

the
playback head. Any cassette I've ever seen has a guide attached to the
playback head. If possible, bend the damaged guide back into place.

Usually
this guide is spot welded, therefore the height of the guide might not

have
changed. This guide sets the tracking which usually is not adjustable
because the guide is fixed to the playback head at the factory. On rare
occasions this guide is adjustable.
The tilt of the head sets azimuth which is adjustable on all decks. You

will
have to examine the record and playback heads to see if there is

azimuth
adjustments for both heads. I would expect there is. Head height raises

or
lowers the position of the head gaps on the tape. Azimuth rotates the

gaps
so that they are aligned perpendicular (90 degrees) to the tape.

Azimuth
will have a slight effect on the head height. Another head adjustment

you
might have is zenith. Usually located at the rear of the head, it

tilts
the
face of the head, so that the head is parallel to the tape. This

adjustment
if incorrect, would tilt the top of the head either closer or further

from
the tape than the bottom of the head. It causes uneven head wear and it
causes the tape to scew up and down. As the tape scews, the azimuth and


tracking will also be out of adjustment. The erase head should also

have
a
non adjustable guide affixed to it.
Check to see that you have these guides in place, the azimuth and

zenith
adjustments, and that the adjustments will move the heads. If you can't
physically align the heads, or the guides are bad, there is no sense in
going any further. you will have to replace whatever mechanics are bad.
You might want to sacrafice an old cassette by cutting away the plastic
shell in the area where the heads contact the tape. This will give you

the
abiltiy to see how the tape rides over the heads. If the tape is

visibly
moving up or down, you will have to correct this. It is impossible to

align
a head to tape that moves all over the place. The basic concept is to

set
all guides at the same height so that the tape enters the shell and

leaves
the shell at the same height. Any guides in between should not raise or
lower the tape as it travels thru the shell.
Post back here with your results and we'll determine the next step.
bg


Marko wrote in message ...
BG: I thought I would check for replies just one more time before I
stopped
NG activity for awhile. Glad I did.


I have a signal generator, alignment tape, scope, and HP5210 freq

meter
that
I have used to set the motor RPM with 1KHz test tone.

I haven't checked yet, but I am hoping that

(1) the head on the far right is the play head
(2) the tape monitor switch will allow me to record a test tone (I

will
use
10KHz) and then monitor it with the play head so that I can align the
record
head.
(3) that the tape guide on the PB head (which has been bent out of the

tape
path) is not necessary for proper tape transfer over the heads.

What worries me is that the tape guide is on the record head and I

must
align the playback head first.

I didn't notice the third head at first and aligned the playback with

the
record head adjustment screw. This worked because the tape guide is

on
the
record head.

How do I start out with proper alignment of the two tape guides before
aligning the heads? One guide, the first one, is affixed to the

transport
frame and the second guide is affixed to the record head. I think

this
problem may have been encountered by
whoever worked on it before it was sent to a resale shop. I could see

that
they had disturbed the paint on the screws. It also had two stretched
belts
and a very dirty rec/play switch on the board, so I'm not sure. The

belts
may have stretched and the grease in the switch may have dried from

sitting
on the shelf for years after they encountered the alignment problem.

What do you suggest? Sincerely, Mark (this is a top post)






----- Original Message -----
From: "bg"
Newsgroups: sci.electronics.repair
Sent: Sunday, July 27, 2003 11:46 PM
Subject: Fisher cassette heads


You need an audio generator, and an AC audio voltmeter with a DB

scale.
If
you have this equipment I'll steer you through it.
bg
Marko wrote in message ...
I have a Fisher cassette deck with separate record and playback

heads.
I
assume that the one in the middle, the large one, is the record

head.

I have a professional alignment tape. How does one align the

record
head?
There is a tape monitor switch which probably is used to compare

input
to
output.

These are ferrite heads with no visible wear, new belts, switches
cleaned
thoroughly: this deck is worth an alignment as opposed to the trash

can
(mabey).

Also, one tape guide (the one on the far left, just to the left of

the
record head) is affixed to the transport frame. The second guide

is
affixed
to the record head. The third tape guide on the playback head is

bent
over
to the side, obviously bent intentionally to get it out of the way.

The
adjustment screw to this bent guide is not accessable for

adjustment
(sloppy
design). The third tape guide is probably not necessary since it

is
only
about a cm from the guide on the record head. This transport may

be
a
piece
of junk due to lousy design.

Any helpful hints will be appreciated Thanks, Mark





"bg" wrote in message
...
You need an audio generator, and an AC audio voltmeter with a DB

scale.
If
you have this equipment I'll steer you through it.
bg
Marko wrote in message ...
I have a Fisher cassette deck with separate record and playback

heads.
I
assume that the one in the middle, the large one, is the record

head.

I have a professional alignment tape. How does one align the

record
head?
There is a tape monitor switch which probably is used to compare

input
to
output.

These are ferrite heads with no visible wear, new belts, switches
cleaned
thoroughly: this deck is worth an alignment as opposed to the trash

can
(mabey).

Also, one tape guide (the one on the far left, just to the left of

the
record head) is affixed to the transport frame. The second guide

is
affixed
to the record head. The third tape guide on the playback head is

bent
over
to the side, obviously bent intentionally to get it out of the way.

The
adjustment screw to this bent guide is not accessable for

adjustment
(sloppy
design). The third tape guide is probably not necessary since it

is
only
about a cm from the guide on the record head. This transport may

be
a
piece
of junk due to lousy design.

Any helpful hints will be appreciated Thanks, Mark














  #5   Report Post  
bg
 
Posts: n/a
Default Fisher cassette heads

It sounds as though you have enough guides to make it work.
Alignment tapes are usually full track. You can't set tracking with it but
you can use it for azimuth. Hopefully the fixed guides are in the right
position. My gut feel is that the azimuth would be the only adjustment you
need to make unless the guides were moved somehow.
The normal method for setting the head height is to record a tone on the
tape and then measure the track positions with a toolmakers microscope. I'm
sure you don't have this equipment, so the next best thing would be to
record a 1000 hz tone on a known good cassette deck and use that tape as
your tracking standard. As you play the tape back in the Fisher deck,
lightly push or lift the playback head to see if the playback level
increases. If the guide on your playback head hasn't been moved, your
tracking should be OK. Flip the tape over and check the levels again. For
every .001 inch that the tracking is off, you lose about .4db of signal
level. If the levels are within 1/2 to 1 db from side one, you probably
won't be able to improve the tracking by moving the playback head guide.
Moving it that small amount would be very difficult, and the guides have to
be wider than the tape by about .001 inch to allow the tape to fit thru it
anyway. So .001 of tape movement is perfectly normal.
To set azimuth on the playback head, use the 10 khz tone on your alignment
tape. There's two ways to do this. One way is to simply adjust your playback
head azimuth for maximum output at 10 khz. The other method is to measure
the phase between the left and right tracks. (lissajous patterns)
Set up your scope for X-Y mode. Plug the left line out into one channel and
the right line out into the other channel. When the two tracks are in
perfect phase alignment, the scope trace should make a line angled at 45
degrees . It looks like this -- (/) .
If the phase alignment is out by 180 degrees the line is angled like
this ---- (\). Between 0 and 180 degrees the line changes to an oval or a
circle. Multiples of 360 degrees will look like it's in phase alignment, but
the length of the line will get shorter. So what you want is the longest
line possible angled like (/). Note that when the azimuth is off, the level
of the 10 khz tone drops off. Lower frequencies are barely affected by bad
azimuth, that's why it is set using a higher frequency tone. If the 45
degree line fluctuates rapidly, there is a problem with the tape moving up
and down. This might be due to the guides not all being at the same height
or bad zenith. Your alignment tape might be stretched also. It doesn't take
very much abuse to stretch a tape. If the tape seems to be bad , try
recording a 10k tone on a good cassette deck and use that for your alignment
tape.
Now that the playback head is in correct azimuth and height. You can align
your record head to your playback head. Check the height of the record head
by recording a 1000 hz tone. Move the record head up or down until you get
maximum output from the playback head. Again, if you flip the tape over, the
levels should playback within about 1db. seeing as the record head has a
guide welded to it , there should be no reason for the record head tracking
to be incorrect. Set the azimuth by recording a 10khz tone and adjust the
record head azimuth for maximum output from the playback head or 0 degree
phase shift between left and right outputs.
You might need to set levels, EQ, bias, and calibrate the VU meters. This
would be hard to do unless the adjustment pots are marked on the circuit
board, but not impossible to figure out.
Let me know how you make out.


Marko wrote in message ...
BG: OK let's give it a try. This time I will get it right about where the
guides are

Originally this machine had four guides:
(1) one solidly affixed to left of erase head
(2) one on left of record head, but affixed to the transport frame
(3) One spot welded to the right side of the record head
(4) One affixed (with miniature screw) to left side of PB head

The one on the right side of the record head is less than a cm from the
guide on the left of the PB head (PB head guide is effectively missing, not
repairable, mangled)

As far as stability of the tape going across the heads goes, I feel that
the 3 remaining guides will be enough, if they are aligned

The two problems are as follows:

(1) The guide to the left of the record head is affixed to frame and all
other guides must correspond to this one or the tape will not ride smoothly
on the heads.

(2) Seems like the guide to the right of the record head should not effect
the path of the tape over the PB head because it is over the screw that is
not for adjustment (the mounting screw that is tightened and not
adjustable). BUT, it does because I didn't notice the 3rd head when I was
adjusting the azimuth for the record head (I thought it was the playback
head at the time). Turning the azimuth adjustment for the record head
affects the path of the tape over the PB head. I recall seeing the PB
amplitude vary on a scope as the azimuth screw for Rec head was turned.

I hope I have written this in a readable manner.

All I can see is that I should adjust the Rec and PB heads over and over
until hopefully they are aligned.

Any ideas or warnings, BG? Thanks for your help. Your advice has given me
a much needed understanding of this situation. Mark
"bg" wrote in message
...
Just about every deck I've ever seen has a guide on the ingoing side of

the
erase head and a guide on the outgoing side of the playback head, with no
other guides in between. It is also common practise to affix the guides

to
the heads, not the chassis. On the chassis there will be posts that hold
the shell in place, they are not tape guides.
I have plenty of time . If you are ready to continue let me know
bg
Marko wrote in message ...
BG: I have reread your post several times and now realize that without

the
guide on the PB head then it is up to me and luck to get it going right.

Unless you have some more advice, thanks much, you've been a great help.
Sincerely, Mark

"bg" wrote in message
...
The heads from left to right are, the erase head, the record head and

the
playback head. Any cassette I've ever seen has a guide attached to the
playback head. If possible, bend the damaged guide back into place.
Usually
this guide is spot welded, therefore the height of the guide might not
have
changed. This guide sets the tracking which usually is not adjustable
because the guide is fixed to the playback head at the factory. On

rare
occasions this guide is adjustable.
The tilt of the head sets azimuth which is adjustable on all decks.

You
will
have to examine the record and playback heads to see if there is

azimuth
adjustments for both heads. I would expect there is. Head height

raises
or
lowers the position of the head gaps on the tape. Azimuth rotates the

gaps
so that they are aligned perpendicular (90 degrees) to the tape.

Azimuth
will have a slight effect on the head height. Another head adjustment

you
might have is zenith. Usually located at the rear of the head, it

tilts
the
face of the head, so that the head is parallel to the tape. This
adjustment
if incorrect, would tilt the top of the head either closer or further

from
the tape than the bottom of the head. It causes uneven head wear and

it
causes the tape to scew up and down. As the tape scews, the azimuth

and

tracking will also be out of adjustment. The erase head should also

have
a
non adjustable guide affixed to it.
Check to see that you have these guides in place, the azimuth and

zenith
adjustments, and that the adjustments will move the heads. If you

can't
physically align the heads, or the guides are bad, there is no sense

in
going any further. you will have to replace whatever mechanics are

bad.
You might want to sacrafice an old cassette by cutting away the

plastic
shell in the area where the heads contact the tape. This will give you

the
abiltiy to see how the tape rides over the heads. If the tape is

visibly
moving up or down, you will have to correct this. It is impossible to
align
a head to tape that moves all over the place. The basic concept is to

set
all guides at the same height so that the tape enters the shell and
leaves
the shell at the same height. Any guides in between should not raise

or
lower the tape as it travels thru the shell.
Post back here with your results and we'll determine the next step.
bg


Marko wrote in message ...
BG: I thought I would check for replies just one more time before I
stopped
NG activity for awhile. Glad I did.


I have a signal generator, alignment tape, scope, and HP5210 freq

meter
that
I have used to set the motor RPM with 1KHz test tone.

I haven't checked yet, but I am hoping that

(1) the head on the far right is the play head
(2) the tape monitor switch will allow me to record a test tone (I

will
use
10KHz) and then monitor it with the play head so that I can align the
record
head.
(3) that the tape guide on the PB head (which has been bent out of

the
tape
path) is not necessary for proper tape transfer over the heads.

What worries me is that the tape guide is on the record head and I

must
align the playback head first.

I didn't notice the third head at first and aligned the playback with

the
record head adjustment screw. This worked because the tape guide is

on
the
record head.

How do I start out with proper alignment of the two tape guides

before
aligning the heads? One guide, the first one, is affixed to the
transport
frame and the second guide is affixed to the record head. I think

this
problem may have been encountered by
whoever worked on it before it was sent to a resale shop. I could

see
that
they had disturbed the paint on the screws. It also had two

stretched
belts
and a very dirty rec/play switch on the board, so I'm not sure. The
belts
may have stretched and the grease in the switch may have dried from
sitting
on the shelf for years after they encountered the alignment problem.

What do you suggest? Sincerely, Mark (this is a top post)






----- Original Message -----
From: "bg"
Newsgroups: sci.electronics.repair
Sent: Sunday, July 27, 2003 11:46 PM
Subject: Fisher cassette heads


You need an audio generator, and an AC audio voltmeter with a DB
scale.
If
you have this equipment I'll steer you through it.
bg
Marko wrote in message ...
I have a Fisher cassette deck with separate record and playback

heads.
I
assume that the one in the middle, the large one, is the record

head.

I have a professional alignment tape. How does one align the

record
head?
There is a tape monitor switch which probably is used to compare

input
to
output.

These are ferrite heads with no visible wear, new belts, switches
cleaned
thoroughly: this deck is worth an alignment as opposed to the

trash
can
(mabey).

Also, one tape guide (the one on the far left, just to the left of

the
record head) is affixed to the transport frame. The second guide

is
affixed
to the record head. The third tape guide on the playback head is

bent
over
to the side, obviously bent intentionally to get it out of the

way.
The
adjustment screw to this bent guide is not accessable for

adjustment
(sloppy
design). The third tape guide is probably not necessary since it

is
only
about a cm from the guide on the record head. This transport may

be
a
piece
of junk due to lousy design.

Any helpful hints will be appreciated Thanks, Mark





"bg" wrote in message
...
You need an audio generator, and an AC audio voltmeter with a DB
scale.
If
you have this equipment I'll steer you through it.
bg
Marko wrote in message ...
I have a Fisher cassette deck with separate record and playback

heads.
I
assume that the one in the middle, the large one, is the record

head.

I have a professional alignment tape. How does one align the

record
head?
There is a tape monitor switch which probably is used to compare

input
to
output.

These are ferrite heads with no visible wear, new belts, switches
cleaned
thoroughly: this deck is worth an alignment as opposed to the

trash
can
(mabey).

Also, one tape guide (the one on the far left, just to the left of

the
record head) is affixed to the transport frame. The second guide

is
affixed
to the record head. The third tape guide on the playback head is

bent
over
to the side, obviously bent intentionally to get it out of the

way.
The
adjustment screw to this bent guide is not accessable for

adjustment
(sloppy
design). The third tape guide is probably not necessary since it

is
only
about a cm from the guide on the record head. This transport may

be
a
piece
of junk due to lousy design.

Any helpful hints will be appreciated Thanks, Mark


















  #6   Report Post  
Marko
 
Posts: n/a
Default Fisher cassette heads

BG: Your post is very well written and I do understand it. Nevertheless, I
will read it several times until I am sure that I have it all understood.

I am currently working on something else which may not be finished for
several days. You probably visit this NG often so I will post a message for
you when I am done. It is not uncommon for something to come along that may
delay this for a few weeks.

I don't think this deck has a zenith adjustment unless it is the play in the
azimuth adjustment. Sounds to me that what makes a low end deck sound
"inexpensive" is partially due to the poor alignment of the heads.

I have done XY plots before so I follow you on the circles and lines on the
CRT. I built a quadraphonic decoder years ago which utilized a broadband
all-pass filter, so I was looking at circles with the 90 degree shift. I
have also determined that the 10KHz tone on the test tape gives the most
accurate adjustment of azimuth.


I'll have to think about the statement you made about the test tape being
full track.

I have been picking up $5 cassette decks and scrapping them if I couldn't
get them going. If the tires were melted all over the transport I scrapped
them. Sometimes the heads and capstan were so coated with oxide that they
were literally ruined from corrosion.

I have a Teac and a Technics here that are totally functional, but they
don't have good speed accuracy.



When I did manage to get belts etc. on it I used the alignment tape to get
both channels to record and play strong in the car. I have a bunch of $3
soft heads I got from MCM that are fine for only recording tapes. When I
aligned these heads there would be one strong track and on weak one if the
azimuth was off.

My point is that it will take a while to understand why the azimuth affects
each track differently (I hope I haven't totally confused you). It usually
hits me a few days later.

If I had your e-mail address I would tell you what happens, but it is
understandable that some people don't like to pass it around. Therefore I
will post a message on this NG when I know something.

Also, concerning your comments about setting EQ etc. I have noticed that
the Dolby is way off when using a tape from another deck. I have started
recording with Dolby off and get much better results.

The adjustment pots on this Fisher are labeled on the board. I don't know
what to do with them though. Possibly after I get these heads aligned you
will help me with the electronics.

Thanks a lot BG, even if this deck turns out to be a scrapper I have learned
a lot. Sincerely, Mark


"bg" wrote in message
...
It sounds as though you have enough guides to make it work.
Alignment tapes are usually full track. You can't set tracking with it but
you can use it for azimuth. Hopefully the fixed guides are in the right
position. My gut feel is that the azimuth would be the only adjustment you
need to make unless the guides were moved somehow.
The normal method for setting the head height is to record a tone on the
tape and then measure the track positions with a toolmakers microscope.

I'm
sure you don't have this equipment, so the next best thing would be to
record a 1000 hz tone on a known good cassette deck and use that tape as
your tracking standard. As you play the tape back in the Fisher deck,
lightly push or lift the playback head to see if the playback level
increases. If the guide on your playback head hasn't been moved, your
tracking should be OK. Flip the tape over and check the levels again. For
every .001 inch that the tracking is off, you lose about .4db of signal
level. If the levels are within 1/2 to 1 db from side one, you probably
won't be able to improve the tracking by moving the playback head guide.
Moving it that small amount would be very difficult, and the guides have

to
be wider than the tape by about .001 inch to allow the tape to fit thru it
anyway. So .001 of tape movement is perfectly normal.
To set azimuth on the playback head, use the 10 khz tone on your alignment
tape. There's two ways to do this. One way is to simply adjust your

playback
head azimuth for maximum output at 10 khz. The other method is to measure
the phase between the left and right tracks. (lissajous patterns)
Set up your scope for X-Y mode. Plug the left line out into one channel

and
the right line out into the other channel. When the two tracks are in
perfect phase alignment, the scope trace should make a line angled at 45
degrees . It looks like this -- (/) .
If the phase alignment is out by 180 degrees the line is angled like
this ---- (\). Between 0 and 180 degrees the line changes to an oval or a
circle. Multiples of 360 degrees will look like it's in phase alignment,

but
the length of the line will get shorter. So what you want is the longest
line possible angled like (/). Note that when the azimuth is off, the

level
of the 10 khz tone drops off. Lower frequencies are barely affected by bad
azimuth, that's why it is set using a higher frequency tone. If the 45
degree line fluctuates rapidly, there is a problem with the tape moving up
and down. This might be due to the guides not all being at the same height
or bad zenith. Your alignment tape might be stretched also. It doesn't

take
very much abuse to stretch a tape. If the tape seems to be bad , try
recording a 10k tone on a good cassette deck and use that for your

alignment
tape.
Now that the playback head is in correct azimuth and height. You can align
your record head to your playback head. Check the height of the record

head
by recording a 1000 hz tone. Move the record head up or down until you get
maximum output from the playback head. Again, if you flip the tape over,

the
levels should playback within about 1db. seeing as the record head has a
guide welded to it , there should be no reason for the record head

tracking
to be incorrect. Set the azimuth by recording a 10khz tone and adjust the
record head azimuth for maximum output from the playback head or 0 degree
phase shift between left and right outputs.
You might need to set levels, EQ, bias, and calibrate the VU meters. This
would be hard to do unless the adjustment pots are marked on the circuit
board, but not impossible to figure out.
Let me know how you make out.


Marko wrote in message ...
BG: OK let's give it a try. This time I will get it right about where

the
guides are

Originally this machine had four guides:
(1) one solidly affixed to left of erase head
(2) one on left of record head, but affixed to the transport frame
(3) One spot welded to the right side of the record head
(4) One affixed (with miniature screw) to left side of PB head

The one on the right side of the record head is less than a cm from the
guide on the left of the PB head (PB head guide is effectively missing,

not
repairable, mangled)

As far as stability of the tape going across the heads goes, I feel that
the 3 remaining guides will be enough, if they are aligned

The two problems are as follows:

(1) The guide to the left of the record head is affixed to frame and all
other guides must correspond to this one or the tape will not ride

smoothly
on the heads.

(2) Seems like the guide to the right of the record head should not

effect
the path of the tape over the PB head because it is over the screw that

is
not for adjustment (the mounting screw that is tightened and not
adjustable). BUT, it does because I didn't notice the 3rd head when I

was
adjusting the azimuth for the record head (I thought it was the playback
head at the time). Turning the azimuth adjustment for the record head
affects the path of the tape over the PB head. I recall seeing the PB
amplitude vary on a scope as the azimuth screw for Rec head was turned.

I hope I have written this in a readable manner.

All I can see is that I should adjust the Rec and PB heads over and over
until hopefully they are aligned.

Any ideas or warnings, BG? Thanks for your help. Your advice has given

me
a much needed understanding of this situation. Mark
"bg" wrote in message
...
Just about every deck I've ever seen has a guide on the ingoing side of

the
erase head and a guide on the outgoing side of the playback head, with

no
other guides in between. It is also common practise to affix the guides

to
the heads, not the chassis. On the chassis there will be posts that

hold
the shell in place, they are not tape guides.
I have plenty of time . If you are ready to continue let me know
bg
Marko wrote in message ...
BG: I have reread your post several times and now realize that

without
the
guide on the PB head then it is up to me and luck to get it going

right.

Unless you have some more advice, thanks much, you've been a great

help.
Sincerely, Mark

"bg" wrote in message
...
The heads from left to right are, the erase head, the record head

and
the
playback head. Any cassette I've ever seen has a guide attached to

the
playback head. If possible, bend the damaged guide back into place.
Usually
this guide is spot welded, therefore the height of the guide might

not
have
changed. This guide sets the tracking which usually is not

adjustable
because the guide is fixed to the playback head at the factory. On

rare
occasions this guide is adjustable.
The tilt of the head sets azimuth which is adjustable on all decks.

You
will
have to examine the record and playback heads to see if there is

azimuth
adjustments for both heads. I would expect there is. Head height

raises
or
lowers the position of the head gaps on the tape. Azimuth rotates

the
gaps
so that they are aligned perpendicular (90 degrees) to the tape.

Azimuth
will have a slight effect on the head height. Another head

adjustment
you
might have is zenith. Usually located at the rear of the head, it

tilts
the
face of the head, so that the head is parallel to the tape. This
adjustment
if incorrect, would tilt the top of the head either closer or

further
from
the tape than the bottom of the head. It causes uneven head wear and

it
causes the tape to scew up and down. As the tape scews, the azimuth

and

tracking will also be out of adjustment. The erase head should also

have
a
non adjustable guide affixed to it.
Check to see that you have these guides in place, the azimuth and

zenith
adjustments, and that the adjustments will move the heads. If you

can't
physically align the heads, or the guides are bad, there is no sense

in
going any further. you will have to replace whatever mechanics are

bad.
You might want to sacrafice an old cassette by cutting away the

plastic
shell in the area where the heads contact the tape. This will give

you
the
abiltiy to see how the tape rides over the heads. If the tape is

visibly
moving up or down, you will have to correct this. It is impossible

to
align
a head to tape that moves all over the place. The basic concept is

to
set
all guides at the same height so that the tape enters the shell and
leaves
the shell at the same height. Any guides in between should not raise

or
lower the tape as it travels thru the shell.
Post back here with your results and we'll determine the next step.
bg


Marko wrote in message ...
BG: I thought I would check for replies just one more time before

I
stopped
NG activity for awhile. Glad I did.


I have a signal generator, alignment tape, scope, and HP5210 freq

meter
that
I have used to set the motor RPM with 1KHz test tone.

I haven't checked yet, but I am hoping that

(1) the head on the far right is the play head
(2) the tape monitor switch will allow me to record a test tone (I

will
use
10KHz) and then monitor it with the play head so that I can align

the
record
head.
(3) that the tape guide on the PB head (which has been bent out of

the
tape
path) is not necessary for proper tape transfer over the heads.

What worries me is that the tape guide is on the record head and I

must
align the playback head first.

I didn't notice the third head at first and aligned the playback

with
the
record head adjustment screw. This worked because the tape guide

is
on
the
record head.

How do I start out with proper alignment of the two tape guides

before
aligning the heads? One guide, the first one, is affixed to the
transport
frame and the second guide is affixed to the record head. I think

this
problem may have been encountered by
whoever worked on it before it was sent to a resale shop. I could

see
that
they had disturbed the paint on the screws. It also had two

stretched
belts
and a very dirty rec/play switch on the board, so I'm not sure.

The
belts
may have stretched and the grease in the switch may have dried from
sitting
on the shelf for years after they encountered the alignment

problem.

What do you suggest? Sincerely, Mark (this is a top post)






----- Original Message -----
From: "bg"
Newsgroups: sci.electronics.repair
Sent: Sunday, July 27, 2003 11:46 PM
Subject: Fisher cassette heads


You need an audio generator, and an AC audio voltmeter with a DB
scale.
If
you have this equipment I'll steer you through it.
bg
Marko wrote in message ...
I have a Fisher cassette deck with separate record and playback
heads.
I
assume that the one in the middle, the large one, is the record

head.

I have a professional alignment tape. How does one align the

record
head?
There is a tape monitor switch which probably is used to compare
input
to
output.

These are ferrite heads with no visible wear, new belts,

switches
cleaned
thoroughly: this deck is worth an alignment as opposed to the

trash
can
(mabey).

Also, one tape guide (the one on the far left, just to the left

of
the
record head) is affixed to the transport frame. The second

guide
is
affixed
to the record head. The third tape guide on the playback head

is
bent
over
to the side, obviously bent intentionally to get it out of the

way.
The
adjustment screw to this bent guide is not accessable for

adjustment
(sloppy
design). The third tape guide is probably not necessary since

it
is
only
about a cm from the guide on the record head. This transport

may
be
a
piece
of junk due to lousy design.

Any helpful hints will be appreciated Thanks, Mark





"bg" wrote in message
...
You need an audio generator, and an AC audio voltmeter with a DB
scale.
If
you have this equipment I'll steer you through it.
bg
Marko wrote in message ...
I have a Fisher cassette deck with separate record and playback
heads.
I
assume that the one in the middle, the large one, is the record

head.

I have a professional alignment tape. How does one align the

record
head?
There is a tape monitor switch which probably is used to compare
input
to
output.

These are ferrite heads with no visible wear, new belts,

switches
cleaned
thoroughly: this deck is worth an alignment as opposed to the

trash
can
(mabey).

Also, one tape guide (the one on the far left, just to the left

of
the
record head) is affixed to the transport frame. The second

guide
is
affixed
to the record head. The third tape guide on the playback head

is
bent
over
to the side, obviously bent intentionally to get it out of the

way.
The
adjustment screw to this bent guide is not accessable for

adjustment
(sloppy
design). The third tape guide is probably not necessary since

it
is
only
about a cm from the guide on the record head. This transport

may
be
a
piece
of junk due to lousy design.

Any helpful hints will be appreciated Thanks, Mark



















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Portable Cassette Player w/Recording Capabilities Greg Electronics 0 August 3rd 03 08:25 PM


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