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  #1  
03-12-2022, 08:23 AM
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I've become interested in playing around with 1/2" open reel videotape machines and I now have several in my collection ranging from the B&W skip-field CV-2600 to the color EIAJ AV-8650.

These units are in varying condition and I want to try my hand at restoring the rougher units. And for that I need tape stock.

I only have a handful of open-reel tapes and they fall into two categories - tapes I don't want accidentally damaged and tapes with sticky-shed syndrome that require baking before they'll play at all. Obviously nothing is going to be as good as the correct tape stock, but NOS tape is rare and expensive and with my experience so far I'd hate to spend the money to discover it has sticky-shed too.

I've experimented with some VHS tape (T-120) but it's noticeably thinner than the real stuff and seems prone to stretching as a result. Good enough for basic transport testing but not so good for much else.

Betamax or first-gen oxide Betacam seem like the obvious things to try next, but I thought it worth asking:

Does anyone have insight into any other formats that can suggest tape that might work better?

"I can make mistakes myself just fine." - Don Williams
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  #2  
03-13-2022, 08:31 AM
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I can't help but it's a really interesting question.

As you've rightly worked out cassette stock is not designed to be handled and is a lot thinner. I don't know the quality of recording that you're expecting but you may run in to issues interchanging stocks as the recording bias of the machine may be vastly different to the non-standard stock which is going to make recording an absolute pain. This can be adjusted I'm certain but it's going to be a non-trivial adjustment

Domestic video tape will use the FM carrier for a bias around the 4.5MHz range with the tape formulated to account for this, different recording strategies may be troublesome if there's baseband & bias in use or modulation to a vastly different carrier, the tape may be 'blind' to the frequencies and create issues. This is a reason why if you slit video tape and load it in to an audio cassette it sounds like absolute garbage, audio cassette biasing is vastly different to videotape.

These old machines may be even just recorded at baseband, especially as they're only recording luminance. I've no idea though.

I can't help, but this may be something to consider. Sounds like an amazing project though.
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03-13-2022, 04:31 PM
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I've physically handled U-Matic stock -- the station I worked at in the late '90s used it to broadcast commercials and what the station would do is buy bulk 20 minute tapes new. A commercial would be placed on the tape and marked with cue tones. We'd air it until the client said stop or we noticed the playback beginning to degrade.

Then we'd "strip aircarts" -- play the tape to the end of the spot, eject it, cut the tape with a scissors, then yank the tape onto the floor all the way back to the clear leader, cut it, then scotch tape it back together and reuse it.

So from my memory, the U-Matic stock was noticeably thicker. Maybe still not as robust as the EIAJ stuff but certainly moreso than VHS. I actually have enough NOS 3/4" that I'm willing to sacrifice one except I don't have a way to accurately slit the stock down to size.

Given that Betamax was conceived as a cost-reduced U-Matic, I'm wondering how that influenced the tape stock, and whether there may be a difference in tape thickness between, say, newer L-500 blanks and if I got a late '70s rental tape off of eBay.

The objective I'm really aiming for is something I can make a sample recording on one of the machines and then play it back on 1-2 of the others to see how they handle it. It wouldn't be for recording anything I would expect to keep and if it was only good for 3-4 playbacks before the tape would stretch that would be okay.

One thing I want to do is understand how close the skip-field CV series signal is to the EIAJ standard and whether playing a CV tape back on an AV machine (and vice versa) gives any indication that there's a recording there that it can't parse (eg, audio only, scrambled picture, etc.).

This is in equal parts toward understanding the potential for identifying recovering otherwise lost TV shows recorded on one of these old tapes and also as a method for generating for interesting video effects. (Flipping the Color/BW switch on the color EIAJ machines never fully kills the color, for example.)

I'm also interested in learning to use an oscilloscope to work on some of these machines so their simpler electronics seems like a good place to start.

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03-13-2022, 04:57 PM
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Quote:
Originally Posted by WildcatMatt92 View Post
I've physically handled U-Matic stock -- the station I worked at in the late '90s used it to broadcast commercials and what the station would do is buy bulk 20 minute tapes new. A commercial would be placed on the tape and marked with cue tones. We'd air it until the client said stop or we noticed the playback beginning to degrade.

Then we'd "strip aircarts" -- play the tape to the end of the spot, eject it, cut the tape with a scissors, then yank the tape onto the floor all the way back to the clear leader, cut it, then scotch tape it back together and reuse it.

So from my memory, the U-Matic stock was noticeably thicker. Maybe still not as robust as the EIAJ stuff but certainly moreso than VHS. I actually have enough NOS 3/4" that I'm willing to sacrifice one except I don't have a way to accurately slit the stock down to size.

Given that Betamax was conceived as a cost-reduced U-Matic, I'm wondering how that influenced the tape stock, and whether there may be a difference in tape thickness between, say, newer L-500 blanks and if I got a late '70s rental tape off of eBay.

The objective I'm really aiming for is something I can make a sample recording on one of the machines and then play it back on 1-2 of the others to see how they handle it. It wouldn't be for recording anything I would expect to keep and if it was only good for 3-4 playbacks before the tape would stretch that would be okay.

One thing I want to do is understand how close the skip-field CV series signal is to the EIAJ standard and whether playing a CV tape back on an AV machine (and vice versa) gives any indication that there's a recording there that it can't parse (eg, audio only, scrambled picture, etc.).

This is in equal parts toward understanding the potential for identifying recovering otherwise lost TV shows recorded on one of these old tapes and also as a method for generating for interesting video effects. (Flipping the Color/BW switch on the color EIAJ machines never fully kills the color, for example.)

I'm also interested in learning to use an oscilloscope to work on some of these machines so their simpler electronics seems like a good place to start.
It's definitely a cool project.

I could get really nerdy on this but the 1/2" cassette stock (Betamax, VHS, Video2000) is quite different to UMatic stock, part of that was making a thinner substrate tape to accommodate the smaller cassette form, if you tried to wind 750 feet of UMatic tape it would be a chunky tape pack and would have been outside of Sony's spec for the Betamax cassette, obviously ignoring the tape width.

Sony determined the size of the cassette as 0th specification for the Betamax system, based on the Sony staff handbook which was an approximately A5 pocketbook.

There are (and this is conjecture) considerations regarding shuttling of tapes, UMatic would have (at least in principal) been subject to repeated shuttling during editing operations which I'm not sure the chemistry at the time would have allowed at a reasonable cost on thinner tape. That's just my conjecture though.

I do have hundreds of Betamax and Betacam tapes in the office with me, the tapestock on the later tapes is arguably thicker as (possibly.. this is debatable, it's not clear) it's Betacam tape. Cassette casings for late (mid 90s onward) Betamax tapes are often the same moulding as Betacam SP cassettes and the later 'Metal' tapes almost certainly contain Betacam SP stock. These are the very end of the line Betamax ED tapes for the last gasp attempt at outdoing S-VHS, about a decade after would have stood any chance of getting any foothold in the market.

Basically, I'm convinced that the very late Betamax tapes were simply differently packaged basic Betacam SP tapes. That's only based on the ones that have passed through my hands, and I've not done any chemical analysis on them!

I do have some new oxide (Maxell brand) Betacam tapes, I can compare these with Betamax tape as they may be a touch more durable, I'll check tomorrow. These might be a good, slightly thicker ferric tape and easily available.

Don't use 'metal' tape with this machine (Betacam SP), I'm almost certain you'll get very poor results. Recording strategies for metal tape are rather different to ferric blends or ferrochrome.

I can't speak to the standards, CCIR-A was more common here in this era and beyond very basic explanation I'm not very good at that so EIAJ is well beyond me in scope.

It's always cool to hear about how things were in studios, it's something that fascinates me, I came into this sort of thing long after routine tape work was being done. I worked in radio for a bit, which was never as exciting, carts just got scrubbed and reused, nothing exciting... Where I worked ad sales were so poor ads were often being played out gratis well past their campaign end anyway just to fill some gaps.

It's a cool as frig device, yet simple enough to comprehend so it's going to be a great learning tool.

After years of being a Tektronix fanboy, I've switched to a modern and modest Rigol unit for my own fiddling endeavours and it's a fantastic little unit. It's amazing how far 'scopes have come now. Don't be scared of a modest 'scope like a Rigol or similar now, they're wonderful little units if you're in the market for one. There's not been a better time to learn this stuff with good quality budget units available coupled with tons of online information.

Always get a decent multimeter first though If you've not got a halfway decent multimeter start there is my tip.

Last edited by RobustReviews; 03-13-2022 at 05:01 PM. Reason: Betamax/Betacam brainfarts.
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  #5  
03-13-2022, 07:15 PM
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Quote:
Originally Posted by WildcatMatt92 View Post
but NOS tape is rare and expensive
Put a number on that. What are you calling expensive?

Because there's this: https://amzn.to/3t8w9dw
2500 feet for $140
That's new stock, not NOS.

I don't recall what pricing for this was 20-25 years ago. I may still have some pricing guides from The Tape Co, and some others, and it'd surely be listed. But I may have tossed those years ago. I need to check my hobby paperwork sometime, that's where it'd be.

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03-13-2022, 07:34 PM
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Quote:
Originally Posted by lordsmurf View Post
Put a number on that. What are you calling expensive?

Because there's this: https://amzn.to/3t8w9dw
2500 feet for $140
That's new stock, not NOS.

I don't recall what pricing for this was 20-25 years ago. I may still have some pricing guides from The Tape Co, and some others, and it'd surely be listed. But I may have tossed those years ago. I need to check my hobby paperwork sometime, that's where it'd be.
That's audio-tape is it not?

Probably great for low-frequency, indeed probably great in the audio range at 7.5IPS but we're not in 20kHz band range. I'll try and dig out a datasheet but that will probably roll-off to nothing well before anything approaching video band. I would imagine this is going to need at least partially chromed stock to capture anything in this range at 7.5IPS.

"True" chromium tape hasn't been manufactured for decades due to, well, chromium in suspension not being very pleasant.

It could potentially work, I don't know this machine, but it's not that simple with tape-stock, it's not a one-size fits all.
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  #7  
03-13-2022, 07:48 PM
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$140 is indeed expensive if I don't have reasonable suspicion that the tape stock will work for my purposes. I've been told that modern 1/2" computer tape is very bad from a head wear perspective on these old video machines, so I'm not sure how audio tape would perform. If it would work then yes, that would be a reasonable investment to have a lifetime supply of tape for these machines.

NOS Sony V-30H 5" reels are most of what I find for sale these days and they regularly run $35 each on eBay. If the vintage stock wasn't so prone to sticky-shed this would be a reasonable price but given that 9 of 10 reels I've examined (including 4 of 4 found in V-30H cases) have required baking so I don't think that's a good deal either.

That being said, I appreciate the link and will reach out to the company. Perhaps they'd be willing to provide a smaller sample to determine suitability.

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03-13-2022, 07:55 PM
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With such a potentially tiny head etc if be cautious about using plain ferric audio stock as I think that may cause a lot of clogging, let alone the formulation most likely being wrong for this application.

I think V2000 tape might be just the ticket, heavily chromed video tape stock.

Drop me a PM and I'm happy to post you out a couple of scrap tapes if you want them.

Oh, the data tapes are often ME (Metal Evaporated) which is quite an aggressive formulation in terms of abrasiveness and this machine is going to have a very soft head. A machine will have heads designed for metal tape.

Chrome is the way to go, I'm almost certain. It predates any metal partial formation by a generation and ferric I think may present some issues.

I'm no expert here, just thinking it through logically.
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