How to adjust VCR rewind speed?

[TOM1]

Hello,
here is the topic of method to measure estimated tail of tape:
https://www.quora.com/How-does-the-V...nd-of-the-tape

I would like to know how to adjust the rewind speed at the end/beginning of the tape.
I would like to adjust the settings for Panasonic NV-HS860 and NV-HS930 video recorders.
Is there a potentiometer for this?
Can it be done without an oscilloscope?

In attachment is HS-860 inside.

[latreche34]

I'm not aware of such thing, but the service manual should tell you if such adjustment exists, As far as I know it's programmed into the system control chip and cannot be modified. The algorithm uses the difference between reels' speeds and direction to calculate how much tape left in a given reel and lowers the speed accordingly gradually or in 2 to 3 speeds increments depends on the manufacturer or design.

Cassettes with a larger hub tend to confuse the VCR system control, so it defaults to the lowest speed possible to prevent tape damage.

Use a cassette rewinder if all this is annoying.

[timtape]

This sophisticated speed control system only became necessary in later years when manufacturers started using very fast wind speeds ("jet rewind" etc) for customer convenience. Super fast wind has its downside in a poor tape "pack" on the reel, leaving the tape more vulnerable to to physical damage. Also in that state if the tape becomes contaminated with mold, the mold can more easily contaminate the actual surface of the tape rather than just the edge of the tape wind. Another case of short term convenience winning over long term preservation.

[TOM1]

Timtape:
The informations are interesting, but I am interested in the possibility of setting...

[latreche34]

Look in the service manual, but again highly likely there is no such setting, Haven't come across one personally.

[timtape]

Quote:

Originally Posted by TOM1

Timtape:
The informations are interesting, but I am interested in the possibility of setting...

What do you intend achieve by changing the speed?

[TOM1]

A change was made in the service.
The HS-930 behaves differently so they had to adjust it there and I want to revert it back.
I'll try to contact service and hope they can tell me how to do it.

[latreche34]

Which service? You should be aware that there is no official support exists for VCRs, Manufacturers stopped VCR support over 20 years ago.

[TOM1]

Of course, I don't mean Panasonic's official support.
HS-930 was under repair.
In another thread I addressed the bar at the bottom of the video during playback.
Turns out it was the head motor that was faulty, not the head itself.
This problem was solved by the maintenance man, but he made a change/adjustment of the rewind according to himself.
Therefore, the HS-930 now rewinds differently than it was set by the manufacturer.

That's all..

[latreche34]

Then ask him to change it back, Even if this was possible it requires some special service remote control to change system control parameters that you don't have access to with normal remote control.

[TOM1]

I got a reply that the MODE SWITCH was being cleaned.
I don't know what all this part does, but it has to do with the mechanics and also with rewind.

[latreche34]

The mode switch has nothing to do with changing rewind speed, I think you're just confused about what was wrong with the VCR and what the repair guy did actually fix, Could be a language barrier between the two of you or you are just not familiar with the technicality of the VCR and you did not understand what he is talking about. In any case as I suspected, there is no such procedure to alter the rewind or fast forward speed since it is programmed in the system control chip. Just use it as is or get a tape rewinder as I suggested before.

[TOM1]

Quote:

Originally Posted by latreche34

you are just not familiar with the technicality of the VCR and you did not understand what he is talking about.

Yes, this is the correct reasoning...

I am a technician, but in a different electrical field.
The repairman deliberately does not explain anything in detail because he protects his know-how.
The only thing I know for 100% is that the VCR behaves differently when rewinding than before. This change could not have happened by accident. The rewind system was changed only after the repair.
It looks like the mechanic himself doesn't know why the VCR behaves this way and doesn't remember the difference because he didn't try the previous (correct) settings.

[lordsmurf]

Quote:

Originally Posted by TOM1

The repairman deliberately does not explain anything in detail because he protects his know-how.

Sometimes, sometimes not.

People are always pressing me for knowledge, but sometimes I do decline. The reasoning is holistic to the community, an attempt to not ruin more gear. The phrase "just enough knowledge to be dangerous" can be accurate, and we'd have a lot less VCRs, TBCs, and capture cards "in the wild" if hamfisted morons Google/Youtube "experts" started to damage gear (mostly due to being too damned cheap to pay those of us who are experience and qualified). I just refuse to assist in destruction, stupidity, and negative economic cheapness.

I generally only teach something that won't destroy gear. Though, sadly, it still happens. I'm sure latreche34 remembers the guy that smeared silicon into his VCR. That's still a top 10 "WTF?" for me.

Quote:

Originally Posted by TOM1

It looks like the mechanic himself doesn't know why

Sadly very common. Although, to be honest, some of this old gear can confuse even the best of us, weird stuff happens.

[TOM1]

lordsmurf:
That's understandable...
But I didn't want to fix anything.
I just wanted to understand how it all works.
Unfortunately, I only get snippets/phrases, but no connections.
I'm from the younger generation and they didn't teach us that at school anymore.