Leader sensor difference between VCRs?

vikinagy97 · #1 12-05-2022, 04:09 AM

I have a Daewoo ST230K VCR and I tested it opened. I saw that when it reaches the end of the tape, the leader can go to the spinning head drum. On a Hungarian forum, however, someone wrote that the leader should not touch the spinning head because it is harmful if it is touched by a material other than the magnetic tape. But the VCR still works, plays back audio and picture well.

I also tested another VCR, a FUNAI 31D-850. At the end of tapes, it stops before the leader reaches the head drum. Therefore, the last few minutes of recordings made with the Daewoo VCR cannot be played back with the Funai VCR. I don't understand why there is this difference between them: the leader does not damage the spinning head, then why does this stop earlier? This early stopping is not good; because of this, the very end of the tape cannot be watched.

timtape · #2 12-05-2022, 04:34 AM

The clear plastic tapes have to be spliced onto the tapes at each end. I dont think those splices should be running across the rotary drums and heads as there's risk of head damage. I'm assuming when playing forward the left light sensor which sees the tail tape first activates "stop". And in reverse, the right light sensor sees the leader tape first and activates "stop".

I guess it comes down to what was the VHS standard for stopping the tape. I suspect both machines cant be right!

vikinagy97 · #3 12-05-2022, 05:03 AM

I know that the tape is spliced to the leader. However, the Daewoo VCR, which allows the leader to the spinning head, went through many splices like this, but still works, its picture is normal, watchable. I think those splices are precise, not head-damaging.

I think that the infra light sensors are not at the same place in the two vcrs I mentioned. Cannot they be modified? Because the problem is that the FUNAI does not play 100% of the tapes. Both at the ends and at the beginnings, there are seconds that it cannot play.

How do the S-VHS Vcrs work? Where are the light sensors in them? Close to or far from the spinning head?

timtape · #4 12-05-2022, 05:43 AM

Quote:

Originally Posted by vikinagy97

...How do the S-VHS Vcrs work? Where are the light sensors in them? Close to or far from the spinning head?...

The two light sensors have to be in the same spots, at each end of the cassette because the positions are fixed by the holes in the VHS cassettes. The holes in SVHS cassettes seem to be in the same places as VHS.

All I can think of is that one deck uses the opposite sensor to the other deck to activate "stop".
Which decks and why? No idea, just telling you what I know.

hodgey · #5 12-05-2022, 06:51 AM

Had a look at the daewoo combo I have and looks like the late model daewoo mechanism doesn't have end/start sensors or IR light that shines through the tape at all. Not sure how it works exactly, maybe it relies on the spool sensors or something instead:

no tape sensor.jpg

Idk if any other manufacturers tried something similar, but the other late vcr mechs I looked at all have light sensors at least, even Funai.

latreche34 · #6 12-05-2022, 10:08 AM

It must be cost cutting as those machines at the late days of VHS were selling like $59 on sale days, By that time all VCR's adopted reduced speed scheme at the end of tape so breaking it was not the issue anymore, They can care less about clear leader going all the way to the drum.

timtape · #7 12-06-2022, 02:15 AM

Quote:

Originally Posted by latreche34

It must be cost cutting as those machines at the late days of VHS were selling like $59 on sale days, By that time all VCR's adopted reduced speed scheme at the end of tape so breaking it was not the issue anymore, They can care less about clear leader going all the way to the drum.

The clear plastic leaders are much thicker and stronger than the actual magnetic tape but they have their limits like everything. Yes the reduced speed at tape ends was a good thing but the better older designs did not fast wind nearly as fast as these later machines were to wind the tape when away from the tape ends. Leader breaking had not really been a problem earlier because the fast wind speeds in the older machines were not rocket fast anyway. The leader sensors gave the deck's brakes enough time to slow and stop the tapes before encountering a "hard landing".

But while the super fast winds of later decks are convenient for the user, not so convenient for the tape. Tapes like to be stored on the reels evenly with no protuding strands of tape from start to finish. If not, sections of the tape can be squashed especially when transported or handled roughly. Fast winding is a recipe for an uneven tape wind with so called "popped strands" which makes the tape edges vulnerable to crushing and loss of signal when played.

hodgey · #8 12-06-2022, 08:57 AM

The Daewoo (or the one I have at least) does slow down the rewind when it gets close to the start of the tape (as do other 2000s fast rewind vcrs for that matter), though it lets the tape run all the way until it stops rather than stopping from the tape sensors. This does result in the leader part of the tape making it's way up to the drum, though idk if it's an issue. It then rolls the tape forwards a little bit again before stopping entirely. The leader should be able to handle it fine, whether it potentially causes extra head wear idk though it's not like 2000s daewoo VCRs are worth much anyhow.

I have experienced the issue of VCRs not starting early enough on tapes on VHS-C tapes on VCRs compared to a camcorder, though that's probably more to do with them being in the adapters and the longer tape path on a VCR compared to a camcorder mechanism.