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  #1  
Old 09-29-2017, 12:27 PM
Outland Outland is offline
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Safety Record Switch

I have the same VCR and same problem described here.

However, I don't know where the 'safety record switch' described in the thread is. Where is it usually?

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  #2  
Old 09-29-2017, 12:50 PM
Chip Chester Chip Chester is offline
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It will be a microswitch-type thing that senses whether the record tab is present in the cassette when inserted. So look where the trailing edge of the cassette sits when inserted. The record tab is about 3/8" square, and sits about a half-inch inboard of the left corner of the cassette, as viewed when inserting it into the slot. The cavity left is usually about 1/8" deep or so. Tab-out=no record.

The sensing arm of the switch would sit about an inch below your picture, lower left corner. It's not on that chassis...

There is probably also a tape tension switch that will issue a stop if the tension drops below a certain level. That may be somewhere on the chassis, and more likely to cause the problem referenced in the link you supplied. I've never tried to change the state of the record tab whilst recording, so I can't speak to what effect that would have.

Chip
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Old 09-29-2017, 12:57 PM
Outland Outland is offline
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I'm not sure why the tape tension or safety record switch would prompt an eject as opposed to a stop in any case. The VCR works great when it does, it just randomly ejects every once in a while.

I was thinking it might also be the mode switch.

Thanks for the explanation.
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Old 09-30-2017, 12:26 AM
Outland Outland is offline
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I just took it apart, and the record safety tab switch is plastic.

What would cause a '95 Panasonic VCR (PV-4551) to randomly eject?
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  #5  
Old 09-30-2017, 01:10 PM
centralradio centralradio is offline
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I had similar issues where the tab in the video cassette was the issue that made the tape eject in record mode.Sometimes the tabs gets pushed in alittlebit and it activates the anti record function on the VCR.I end up putting a couple pieces of tape over the tab and it works fine.
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Old 09-30-2017, 03:27 PM
Outland Outland is offline
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How can I eliminate the tab sensor as the issue?

The chassis needs to be pulled to get to the switch. Is there a video or something of that nature? I've never done it before.
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  #7  
Old 10-01-2017, 01:48 PM
Chip Chester Chip Chester is offline
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If the machine is put together enough to run, maybe try this:

For the record tab, get a cassette whose content you can record over, but with the record tab removed, and make up a plastic shim and attach it to the non-sticky side of a post-it note. Place it over the record tab location with the sticky side of the post-it, and use a string or piece of tape to pull it away while recording is underway. See if it just stops, stops and ejects, or just drops out of record.
It could be that the switch mechanism is worn just enough that the slight extra thickness on the record tab 'cures' it. In that case, a shim or spacer at the right place in that mechanism (not on the cassette itself) could make it all better for the next 25 years.

Also, don't overlook a tensioning issue. If the tape path loses tension, the next thing I would have the deck do, if I were the designer, would be to have it eject because that would protect the tape the quickest -- get it unlaced, away from the spinning head (which would eat an un-tensioned tape) and back safely in the cassette.

Good luck! Just be systematic about your testing, and you'll get to the true cause.

Chip

Last edited by Chip Chester; 10-01-2017 at 01:55 PM.
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  #8  
Old 10-02-2017, 09:26 AM
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Electronic M Electronic M is offline
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Quote:
Originally Posted by Chip Chester View Post

Also, don't overlook a tensioning issue. If the tape path loses tension, the next thing I would have the deck do, if I were the designer, would be to have it eject because that would protect the tape the quickest -- get it unlaced, away from the spinning head (which would eat an un-tensioned tape) and back safely in the cassette.

Chip
I've seen enough dead take up troubles to want the deck to try to pull the tape back into the cassette and stop there. If the take up did not work and the mech tried and failed to pull the tape in it is better to give the user a chance to put the deck into un-threaded rewind or fastforward (if either works) to ensure the tape is back in it's shell and won't get crinkled by hanging out of the cassette on eject...
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Old 10-03-2017, 12:12 AM
Outland Outland is offline
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I'm lucky because 12voltvids published a video detailing the same or very similar chassis removal video here.

https://www.youtube.com/watch?v=hZmGY9ztmWY

While I have the chassis out, is there anything else I should do? I'm planning to change the belts and clean the mode switch (as detailed in the video) as well.

I like this VCR and have owned it since new, so I would like to keep it in optimal working condition.

Quote:
For the record tab, get a cassette whose content you can record over, but with the record tab removed, and make up a plastic shim and attach it to the non-sticky side of a post-it note. Place it over the record tab location with the sticky side of the post-it, and use a string or piece of tape to pull it away while recording is underway. See if it just stops, stops and ejects, or just drops out of record.
Thanks, I will give this a try.

Last edited by Outland; 10-03-2017 at 12:23 AM.
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