OT - pre-recorded tape loses color

Caruso wrote on 2/19/2005, 5:31 AM
I recently came across a commercially manufactured copy of the movie "Top Gun" on a two-hour 8mm cassette. I don't remember when that movie was produced, but have to thing that this tape is at least seven or eight years old, perhaps older. I watched it the other night, and one section, perhaps three or four minutes in length about two thirds of the way through the movie, turns to black and white. If I stop the tape and start it again, a brief flicker of the color information appears, but, then, all color is lost.

This B&W section is otherwise pristine in appearance - no static, lines, or drop outs.

What would cause a loss of color on just one section of the tape? I didn't know that could happen. We're talking about standard 8mm analog tape run through one of the best analog 8mm cams Sony ever offered the consumer.

Just curious.

Thanks.
Caruso

Comments

farss wrote on 2/19/2005, 6:30 AM
I've seen this happne on all analogue formats, thankfully they're a think of the past.
I'm not too certain of the technical details but it's I think something to do with the color information being recorded on a HF carrier. When the base warps the heads aren't at able to read the HF signal and goodbye color. If you can find an old deck with manual tracking control you just might be able to get it back.

Worst I've had it on was UMatic, yuck. the chroma would come and go a few frame on then off then it'd shift from the luminance signal, then you'd only have one color and then it'd all be back. Nightmare stuff to work with and then there's dropouts as well.
Bob.
Caruso wrote on 2/19/2005, 11:53 AM
Fortunately, I can honestly state that I don't care at all about the condition of a commercially pre-recorded copy of "Top Gun". OTOH, out of curiosity, I'd love to know more about what causes this problem. Farss, (and thanks for the reply, BTW), you state that you believe it has something to do with tape warpage disrupting the tracking of the HF signal.

I'm not saying you aren't right, but, I have a collection of some 200 8mm analog tapes. None (until I acquired this one) suffer from this symptom. Why would one pre-recirded 8mm tape suffer this malady when none of my other tapes seem to? Just curious. If the tape is warped, in what direction would it warp to cause this problem. I'm certainly no expert in these matters, but, I thought the transport of my 8mm Camcorder/VCR would flatten out the tape as it runs through.

Curious to hear from anyone.

Caurso
farss wrote on 2/19/2005, 2:45 PM
There was something on the web I saw that went into this in some detail, I think it was a company in one of the old eastern blcok countries that specialised in archival retrieval that had written it.
Some things I do remember. It only needs a tape to strecth 1% in length and it's untrackable. Tape may stretch unequally accross the tape, this turns the diagonal track into a banana shape, once that happens nothing can track it.
Why did it happen to just one tape, commercial dubs are oftenly done on the cheapest stock they can buy and the alignment of their machines can be right on the limit.
Bob.
Caruso wrote on 2/20/2005, 12:40 AM
. . . but, farss, could the tape warp just so (or stretch just so) that the only symptom would be loss of color info? The remaining B&W is simply clear as a bell. No distortion, no flickering, no drop outs, no snow, nothing.

Again, I really appreciate your taking the time to reply, and you probably have a lot more knowledge about tracking, tape construction, etc than I (I have virtually none). So, I don't want to be contrary . . . it just seems strange to me - that's all.

Over the years, I've collected tapes - most top quality (well, best consumer quality I could find) - some were of marginal quality. The cheap tapes tended to clog my cam's heads, develop drop outs, or (worst of all), get tangled up in the mechanism (I really, really hate when that happens).

You can imagine how the recorded image suffered when these cheap tapes failed. None, however, had this strange loss of color info.

That's why this seems so strange to me.
Anyhow, the content is neither important nor unreplaceable.
Thanks again for your reply.

Caruso
farss wrote on 2/20/2005, 12:46 AM
I'll admit I'm right at the limits of my knowledge. Perhaps a magnetic field but I'd still go for tape warp/stretch.