This is my own VCR. There is a small horizontal section of picture that
is visible at the bottom of the screen. It seemed just like dirty video
heads symptom but cleaning them had no effect. I replaced them but the
problem is still there. I was talking to Ben from Tip Top Tuner today
and mentioned Fisher. He told me about two small capacitors that could
cause this problem. Not sure if its the same machine or where they
might be though. The tracking control seems to have no effect
whatsoever. Does anyone remember this symptom on this machine. Its
about 20 years old but stereo and really built well so I'd like to keep
it. Thanks for any assistance. Lenny Stein, Barlen Electronics.

ha escrito:

This is my own VCR. There is a small horizontal section of picture that
is visible at the bottom of the screen. It seemed just like dirty video
heads symptom but cleaning them had no effect. I replaced them but the
problem is still there. I was talking to Ben from Tip Top Tuner today
and mentioned Fisher. He told me about two small capacitors that could
cause this problem. Not sure if its the same machine or where they
might be though. The tracking control seems to have no effect
whatsoever. Does anyone remember this symptom on this machine. Its
about 20 years old but stereo and really built well so I'd like to keep
it. Thanks for any assistance. Lenny Stein, Barlen Electronics.

this reminds me of a common fault with early 90s JVCs. a cap on the
drum motor pcb of about 3.3 uF used to go leaky and cause this problem,
i expect you've got similar.
-B

wrote:
This is my own VCR. There is a small horizontal section of picture that
is visible at the bottom of the screen. It seemed just like dirty video
heads symptom but cleaning them had no effect. I replaced them but the
problem is still there. I was talking to Ben from Tip Top Tuner today
and mentioned Fisher. He told me about two small capacitors that could
cause this problem. Not sure if its the same machine or where they
might be though. The tracking control seems to have no effect
whatsoever. Does anyone remember this symptom on this machine. Its
about 20 years old but stereo and really built well so I'd like to keep
it. Thanks for any assistance. Lenny Stein, Barlen Electronics.

I got a question of my own. WHY THE **** ARE YOU STILL USING VHS,
RETARD?

Malissa Baldwin wrote:

This is my own VCR. There is a small horizontal section of picture that
is visible at the bottom of the screen. It seemed just like dirty video
heads symptom but cleaning them had no effect. I replaced them but the
problem is still there. I was talking to Ben from Tip Top Tuner today
and mentioned Fisher. He told me about two small capacitors that could
cause this problem. Not sure if its the same machine or where they
might be though. The tracking control seems to have no effect
whatsoever. Does anyone remember this symptom on this machine. Its
about 20 years old but stereo and really built well so I'd like to keep
it. Thanks for any assistance. Lenny Stein, Barlen Electronics.


I got a question of my own. WHY THE **** ARE YOU STILL USING VHS,
RETARD?

More useful input, I see. A pattern is emerging...

The video head's drum motor assembly has a magnetic cover that is
secured on with 2 or 3 screws (usualy non magnetic metal). On its rim
you'll see 1 or 2 black dots which are tiny magnets glued on to
generate a "pg" pulse. This pulse reports phase of drum rotation and
tells the head preamp when to read the video heads and when to switch
off in one rotation. A pg sensor is situated close to the lower drum
assembly to pick up these pulses.
1) Have you removed this part while cleaning and reinstalled it
incorrectly?.
2) I've had a case or 2 where the magnets were worn down and they
wouldn't generate enough of a pulse.
3) I've had cases where the allignment of lower drum with respect to
upper drum was out. An allen key locks the drum position to the shaft.
Has this loosened? Can the upper drum be shifted (with a bit of force)
while holding the lower drum tight?.
4) Bad pg sensor or a fault somewhere down the pg processing line.
5) Bad rotary transformer. The upper drum assy has a rotary transformer
primary winding housed in a ferrite base. This couples the video signal
to a similar secondary winding which is stationary. I've seen breaks in
these windings, and have rewound them to some degree of usability.
Jango

jango2 wrote:
The video head's drum motor assembly has a magnetic cover that is
secured on with 2 or 3 screws (usualy non magnetic metal). On its rim
you'll see 1 or 2 black dots which are tiny magnets glued on to
generate a "pg" pulse. This pulse reports phase of drum rotation and
tells the head preamp when to read the video heads and when to switch
off in one rotation. A pg sensor is situated close to the lower drum
assembly to pick up these pulses.
1) Have you removed this part while cleaning and reinstalled it
incorrectly?.
2) I've had a case or 2 where the magnets were worn down and they
wouldn't generate enough of a pulse.
3) I've had cases where the allignment of lower drum with respect to
upper drum was out. An allen key locks the drum position to the shaft.
Has this loosened? Can the upper drum be shifted (with a bit of force)
while holding the lower drum tight?.
4) Bad pg sensor or a fault somewhere down the pg processing line.
5) Bad rotary transformer. The upper drum assy has a rotary
transformer primary winding housed in a ferrite base. This couples
the video signal to a similar secondary winding which is stationary.
I've seen breaks in these windings, and have rewound them to some
degree of usability. Jango

I've seen a shorted cap on the main board take out the PB 9v line...

Mark Z.

I disassembled the head assembly and found that the coils were loose
and slightly lifted in the ferrite tracks of the rotary transformer. I
have heard that this is common on these old Fishers.
I performed the repair using super glue. I tried to get small wooden
wedges in to hold the coils down but could not seem to get them to
stay, so I did one section at a time, holding the coil down with a tiny
stick each time until the glue set. It was very arduous but I did get
it all glued down. Some glue did get on the faces of the ferrite disks
but I wiped it all off. The coils seemed to be laying flat in the
grooves after the procedure however they are not exactly concentric. By
this I mean that the grooves are a slightly larger diameter than the
coils. Therefore the coils are not exactly in the middle of the grooves
in every quadrant if you can picture this. I don't know if they ever
were or even if this very slight discrepancy is of any concern. I had
marked everything and I was very careful to reassemble it all as it was
taken apart. The procedure made no difference at all. The symptoms are
the same. I put the other set of heads back on but that made no
difference either. I still have continuity on both coils but I wonder
if I blundered the procedure somehow. Lenny

Mark D. Zacharias wrote:
jango2 wrote:
The video head's drum motor assembly has a magnetic cover that is
secured on with 2 or 3 screws (usualy non magnetic metal). On its rim
you'll see 1 or 2 black dots which are tiny magnets glued on to
generate a "pg" pulse. This pulse reports phase of drum rotation and
tells the head preamp when to read the video heads and when to switch
off in one rotation. A pg sensor is situated close to the lower drum
assembly to pick up these pulses.
1) Have you removed this part while cleaning and reinstalled it
incorrectly?.
2) I've had a case or 2 where the magnets were worn down and they
wouldn't generate enough of a pulse.
3) I've had cases where the allignment of lower drum with respect to
upper drum was out. An allen key locks the drum position to the shaft.
Has this loosened? Can the upper drum be shifted (with a bit of force)
while holding the lower drum tight?.
4) Bad pg sensor or a fault somewhere down the pg processing line.
5) Bad rotary transformer. The upper drum assy has a rotary
transformer primary winding housed in a ferrite base. This couples
the video signal to a similar secondary winding which is stationary.
I've seen breaks in these windings, and have rewound them to some
degree of usability. Jango

I've seen a shorted cap on the main board take out the PB 9v line...

Mark Z.

wrote:
I disassembled the head assembly --snip-.--
I put the other set of heads back on but that made no
difference either. I still have continuity on both coils but I wonder
if I blundered the procedure somehow. Lenny

Hate to **** on your bonfire, but it might be time to call it a day.
After all we're dealing with a 20 year old unit here, you've already
done what you can. With very good Hifi stereo VHS decks around cheap
second hand, it seems silly to waste more time on this one. Sometimes
it's best to know when to stop and spend time more productively.
Good luck.
-B.

Hate to **** on your bonfire, but it might be time to call it a day.
After all we're dealing with a 20 year old unit here, you've already
done what you can. With very good Hifi stereo VHS decks around cheap
second hand, it seems silly to waste more time on this one. Sometimes
it's best to know when to stop and spend time more productively.
Good luck.
-B.


No, don't give up. I just made a killing fixing 2 Leak valve amplifiers
which were more than 55 years old. . Have you checked out all the other
leads we've been giving you?. We're here to help u crack this case.
Jango.

Now that I've repaired the transformer (I think), someone else said
that it may be a head switching issue. He said to use a dual trace
scope to monitor the preamp output with respect to the PG pulse. Does
this make sense to you and how do I determine where to pick up these
waveforms? I don't work on VCR's much and am not too familiar with this
procedure. I also read yourdetailed post and think that I satisfied all
your questions as far as alignment etc. I was very careful during
disassembly and reassembly to get everything back the way it was. I
really don't want to give up on this unit and appreciate everyone's
help. Lenny.
jango2 wrote:
Hate to **** on your bonfire, but it might be time to call it a day.
After all we're dealing with a 20 year old unit here, you've already
done what you can. With very good Hifi stereo VHS decks around cheap
second hand, it seems silly to waste more time on this one. Sometimes
it's best to know when to stop and spend time more productively.
Good luck.
-B.


No, don't give up. I just made a killing fixing 2 Leak valve amplifiers
which were more than 55 years old. . Have you checked out all the other
leads we've been giving you?. We're here to help u crack this case.
Jango.

jango2 ha escrito:
Hate to **** on your bonfire, but it might be time to call it a day.
After all we're dealing with a 20 year old unit here, you've already
done what you can. With very good Hifi stereo VHS decks around cheap
second hand, it seems silly to waste more time on this one. Sometimes
it's best to know when to stop and spend time more productively.
Good luck.
-B.


No, don't give up. I just made a killing fixing 2 Leak valve amplifiers
which were more than 55 years old. . Have you checked out all the other
leads we've been giving you?. We're here to help u crack this case.


Jango,
Just so there's no misunderstanding here - and I am often one who
keeps going on a device way beyond what others would call reasonable -
I'd never tell anyone to just give up. But in this case, we're dealing
with an awkward fault in a critical and expensive part of the machine,
with a user who admitted himself he does not usually work on vcrs.
Prognosis isn't good.

Not only that, there is a huge difference between investing time and
money in rare 55 year old amplifiers which are collectable and fully
usable today, and an old video machine from a standard on its way to
obsolescence, the like of which can be had for peanuts in any number of
second hand places - usually in better shape and for less cost and time
than repairing this one or finding the necessary parts. Sometimes it
pays more to be reasonable and know when to stop.

-B.

Been ages since i repaired any VCR. The head preamp pack outputs an RF
envelope waveform. Do you have any kind of oscilloscope? We need to
observe a clean output here.Set your time base to 1msec/div and
sensitivity to 0.1 volts/div. A typical waveforms looks like this:
http://www.tangible-technology.com/helical/path.html
We need to find out if the fault lies in the drum assembly + preamp or
later on in signal processing circuits. Tape path alignment is critical
here. A head switching pule is applied to the preamp, this signal is
derived from pg.

To Rev : Sometimes the feeling of accomplishment out weighs any amount
of money received as repair fees. As long as Captainvideo has the time
and inclination to proceed i don't see any reason not to encourage him.