Tape deterioration

[Wonder-Boy]

Today I acquired a working datassette with Load-it. It has got perhaps ten LEDs that tell you how strong the signal from the tape is and you dial in the strongest possible signal when attempting to load something. For one game I got maybe 6/10 and it loaded OK. For other games the signal was lower. For another game I got almost 3/10 and it eventually loaded. For a third I also got 3/10, it started to load but did not load fully. For a fourth game I could not get more than 2/10 and I have never been able to load it. I tried the first game again and the signal was still 6/10 and it loaded without problems.

Is it correct to assume that the signal on tapes gets weaker and weaker over time to eventually disappear?

[ral-clan]

I assume the signal to noise ratio will decrease over the years, as tape particles demagnetize or just are generally demagnetized by the magnetic fields in your house. So this would be an extremely, extremely gradual "erasing" of the tape. I'm not sure if this would account for that much of a difference even over 20 years.

The greater thread is that the magnetic particles that are "glued" to the plastic substrate of the tape start to fall off due to the age of the adhesive. When this starts happening (known as "shedding") you will get severe dropouts (silence in parts of the tape) and lose data entirely. On some old tapes (in bad cases) you can actually see through the tape where the magnetic oxide has fallen off.

[PhotoJim]

It depends, too, on the quality of the tapes. Some tapes are of very high quality and will only very gradually lose content. Cheap tapes might lose content quite rapidly.

Unfortunately, most of the VIC-20 community back in the day was young and poor (otherwise we would have had an expensive computer ) and the quality of cassettes used was often quite bad. Unlike with audio, a cheap Fe2O3 tape doesn't load differently than an expensive CrO2 cassette does... until years later when the later will have aged more gracefully than the former. (I put all my audio on CrO2 tapes back then, but I used Fe2O3 for data. Longevity wasn't even on my mind.)

[ral-clan]

I put all my audio on CrO2 tapes back then, but I used Fe2O3 for data. Longevity wasn't even on my mind.)

That might have been a good move, ironically. Although CrO2 tapes are better in the long run, they are only so when recorded on equipment that has a Cr02 record setting. The datasette had no "Type II" setting, and therefore its record signal was probably calibrated for best results on Fe02 "Type I" cassettes.

[eslapion]

... The datasette had no "Type II" setting, and therefore its record signal was probably calibrated for best results on Fe02 "Type I" cassettes.

True!

Also, I have some voice recording on ordinary iron oxide (FeO2) tapes that date back to 1976 and they sound just as fine as the day they were recorded.

The true problem of signal degradation with datasette comes from head magnetisation. People who uses datasettes never think about the need to clean and most importantly demagnetize the RW head of their machines.

When the RW head gets magnetized, its just like passing a magnet on the surface of the tape every time you read it back. That's the main cause of signal loss, not poor tape quality.

A poor tape will sound like crap the very first time you play it back even if your tape was recorded 5 minutes ago. It will not lose signal strenght any faster than a good one.

A datasette is and remains, first and foremost a tape recorder. It has the same weaknesses as any tape recorder. Its a mechanical device which wears over time, it has a RW head that can magnetize when used and rubber roller that can get dirty and stick to the tape and cause a spooling of the tape around it.

The best for the datasette remains high quality Type I tapes. Not all of them use ferric oxide but all of them are compatible with the 120us equalisation the datasette uses.

There are some special Chrome for Type I tapes that were made by BASF but these are very difficult to find.

[hawk]

Another problem with tapes that affect them over time is "crosstalk" (?). Where the magnatism of the tape layered on the spool leaks onto the other layers. This is most obvious in old music tapes at the start, where you can hear the faint sound of the song starting just before it actually starts. In an audio tape, it would result in increased noise level. I can only assume that the same would be true for a data cassette. If the recording was marginal, the added noise may be enough to add errors to the data.

[d0c]

after i read these posts i now i will have nightmares!!

[Wonder-Boy]

Thank you everybody. I have a demagnetizer cassette (there are many many of those on ebay) but the datassette is too weak to turn it, but it is possible to help turn it a little bit manually if you remove the datassette lid.

I am thinking that if some games are too far gone I can repair them by using a .tap file and save it to a new tape and then splice the tape into the old tape. That way they would work but maybe they souldn't be as collectible, but I think I would rather have games that work in my bookshelf.

[eslapion]

Thank you everybody. I have a demagnetizer cassette (there are many many of those on ebay) but the datassette is too weak to turn it, but it is possible to help turn it a little bit manually if you remove the datassette lid.

Whaaaaat ???? In what condition is your datasette ??

And what kind of demagnetizer cassette are you using?

A demagnetizer cassette does not require "turning", it requires a battery!

If you have something like this:



Please by all means, thrash it immediately.

Added edit:

There were cassette based head demagnetizers sold which mechanically spun a small round magnetized disk near the record head.

These were linked to drive mechanism in cassette housing.

They worked horribly and were almost completely ineffective.

The above picture shows one of these...



What you need is this:



Found here : http://www.longselectronics.com/product ... 565&id=582

That thing costs only 8$ yet it uses a real electrical coil to remove magnetism so why try to save a few pennies on this kind of stuff...

[6502dude]

There were cassette based head demagnetizers sold which mechanically spun a small round magnetized disk near the record head.

These were linked to drive mechanism in cassette housing.

They worked horribly and were almost completely ineffective.

[Wonder-Boy]

Oops, I'll make sure I have the right gear, thanks

[ral-clan]

Yeah, you have been using a crappy old cassette head CLEANER, not a cassette de-magnetizer.

Oh, and I think it is good practice to use this when the deck is in an un-powered state. (Especially when it is an audio deck attached to speakers).

As for splicing new tape into your existing "vintage" shells; this is a bit of a hack. Why not simply open the cassette shell with a screwdriver, remove the old reels, and drop in the newly recorded reels?

[Wonder-Boy]

I didn't think it was possible to do that, but maybe it is better. But I need tape of the right length it may be difficult to find.

[d0c]

thanks but where can i buy this in norway??

http://www.longselectronics.com/product ... 565&id=582

[ral-clan]

I didn't think it was possible to do that, but maybe it is better. But I need tape of the right length it may be difficult to find.

Tape length shouldn't matter. Even a the tape from a C-90 should fit in any standard shell.