VCR JVC HR-A33U loads non-existent tape and re-loads existent
 

Good day, everyone!
I am working on VCR JVC HR-A33U.
Upon powering up it attempts to load a non-existing tape.
When real tape is injected, the machine works more or less
properly. But when tape needs to be ejected, VCR spits it out
and then re-loads it back. Mode switch and alignments were checked
and appear to be in order. (Cleaned and re-assembled more than once,
with all check points observed. There is no problem with that).
This machine loads tapes off capstan motor (not off loading motor)
and I can not figure out how the inserted tape is sensed, what triggers
the capstan motor to start to spin in order to pull the tape in.
Any advice is appreciated.

Viatcheslav

Some older JVC's would have this problem due to a loose grounding screw
underneath the mechanism. It would trigger a tape sensor because the ground
was lifted.

Mark Z.

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"Viatcheslav Riabov" wrote in message
om...
Good day, everyone!
I am working on VCR JVC HR-A33U.
Upon powering up it attempts to load a non-existing tape.
When real tape is injected, the machine works more or less
properly. But when tape needs to be ejected, VCR spits it out
and then re-loads it back. Mode switch and alignments were checked
and appear to be in order. (Cleaned and re-assembled more than once,
with all check points observed. There is no problem with that).
This machine loads tapes off capstan motor (not off loading motor)
and I can not figure out how the inserted tape is sensed, what triggers
the capstan motor to start to spin in order to pull the tape in.
Any advice is appreciated.

Viatcheslav

On many later model machines, inserting the tape moves a plastic lever to
block the sensor momentarily. Usually the left-side sensor.

Mark Z.


"Viatcheslav Riabov" wrote in message
om...
(Viatcheslav Riabov) wrote in message
. com...
Good day, everyone!
I am working on VCR JVC HR-A33U.
Upon powering up it attempts to load a non-existing tape.
When real tape is injected, the machine works more or less
properly. But when tape needs to be ejected, VCR spits it out
and then re-loads it back. Mode switch and alignments were checked
and appear to be in order. (Cleaned and re-assembled more than once,
with all check points observed. There is no problem with that).
This machine loads tapes off capstan motor (not off loading motor)
and I can not figure out how the inserted tape is sensed, what triggers
the capstan motor to start to spin in order to pull the tape in.
Any advice is appreciated.

Viatcheslav

Thank you for reading this.
Right after I posted the above, I found several cracks
near start/end sensors Q701, Q702 and that resolved the problem.
But I am still interested to find out how the tape is sensed to be
pulled in.
Regards,
Viatcheslav