Help! I think I killed my R2R!

[doris]

Hi. This is really embarrassing, but I accidentally used a demagnetizer on my Tascam TSR-8 tape heads with the power on. Now the thing won't record on tracks 1-5. In record mode and during recording I get good strong levels on 2-5 (almost nothing on 1) on the meters, but during playback the levels are very weak (not even enough to show up on the tascam's meters. Also, there is quite a bit of cross talk between tracks now, enough to show up on the meters of the adjacent tracks.

What specifically have I done here? Can someone give me a best case/ worst case scenario? Is this something that is fixable? Or should I accept a learned lesson and start saving up for another?

thanks in advance for any help, and please feel free to berrate, lecture, ridicule, etc.

--bh

[The Ghost of FM]

What you have done is sent approximately the electrical equivalent of 20,000 db to the heads and supporting circuitry. Normally they are looking for about 2 or 3 db's.!

The electronics will need to be repaired and the heads most likely replaced.

Sorry to say but, I hope that Santa has a new machine in your future.

Merry Christmas anyway.

[doris]

well crap. someone had suggested buying another tsr-8 and stealing the cards from it. but i guess if the heads probably didn't make it either then i should probably just start from scratch. are there any simple tests i can do with a multimeter to confirm this? if there is no hope for reasonable repair than i'd rather not sink any money into getting an estimate. that would just put me farther away from a replacement.

well i always wished i had gotten that otari 1/2". now i have a pretty good excuse. If I got a different machine and aligned for 456 (like my tsr-8) would the tracks line up enough that I could save some of the material from my old reels?

thanks for the reply FM.

--doris

[The Ghost of FM]

There probably is an impedance measurement that could be made on the heads to see if they as well got fried along with the channel cards but, I don't know what that spec should be on a normal set to tell you what numbers to look for.

An hour of shop time might be a reasonable investment to really see where you stand.

As for the Otari; If the tape format and speed are the same, you should be ok switching your work over to that machine as long as the Otari has dbx type I professional noise reduction as your TSR 8 had. If not, you will have to purchase additional NR units for the Otari, just as you'd have to do if you went with any other TASCAM model other then the TSR 8.

Good luck!

[doris]

hey FM,
i looking more closely at the heads on this thing, and noticed that everything in the tape path had LOADS of green gunk caked on it. is this tape shed? this is strange because everything was freshly cleaned before all this demagging fiasco started. there is so much crud that it actually hags off the edge of the parts in places. what is this? i tried to take some photos:

--doris

[doris]

more:

[doris]

and more:

[BillyFurnett]

(*Broken-----spacebar)

Hey-Doris,

It's-hard-to-tell-what's-happening-in-those-pics(At-least-for-me),but-you-didn't-happen-to-use-like-less-than-91%-Alcohol-to-clean-the-heads-did-you??

That-looks-like-a-combination-of-the-flakey-kind-of-rust-oxide-from-not-using-Alcohol-that-will-evaporate-and-some-serious
tape-shed!

I'm-not-positive,but-that-pinch-roller-looks-pretty-wailed-on-too.
You-didn't-happen-to-clean-that-with-alcohol-too-did-you?

[The Ghost of FM]

Doris,

The pictures are so blurry that it's dang-near impossible to tell?

Green would definitely be a bizarre color for tape oxide dirt. Usually, it's brown or black unless you are using a weird tape formulation.

In any case, you could try a serious cleaning with Qtips and isopropyl alcohol to see if it comes off but, either way, hitting the electronics with a d-mag wand with the power on, definitely damaged the machine too.

What kind of tape do you use?

What was your cleaning regiment like prior to the accident?

Cheers!

[doris]

BF,-thanks-for-persevering-through-your-handicap-to-post. i used tape head cleaner from RadioShack (isopropanol/ethanol/methanol). it doesn't actually say what the dilution is, but it definitely seems more volatile than grocery store isopropanol (60-80%). but yeah, every part of the tape path (not just the heads) has been gunked. I only cleaned the heads.

FM, my digital camera stinks. i took about 35 pics and those were best of the bunch. the color in the pics is accurate--green! not like what dirty heads look like. I use 456, and i clean the heads before every session. could magnetizing them increase the amount of tape shed??? the tape itself doesn't look raped, though. maybe some sort of physical damage to the heads??? i'm going to clean them off now, and i'll report back.

--doris

[The Ghost of FM]

Doris,

Well, the basic problem that gets created when you do what you did is that you put a permanent magnetic charge into part of the heads and now, as the tape passes over them, the heads are pulling more material away from the tape then they normally would.

This might be the case here.

You may well be able to save the heads by repeatedly demaging them properly and slowly, with the power on the deck, of coarse turned off! and you might be able to bring the heads back to some form of normalcy but the electronics may have been irreparably damaged as well and is why I suggested earlier in a previous post to invest and hour of shop time by a qualified technician to really see where you stand with this.

Cheers!

[doris]

wow, very interesting! after a thorough cleaning and another visit with the evil demagger i now get audio back on all 8 tracks. however, something is still screwy. track 2 bleeds on to 1 on an almost equal level. and a couple tracks are less full sounding than the rest (no bottom end). i thought magnetism on the heads affected high frequency response.

FM, you are right, i need to get a tech to look at it. i will, eventually. its just that the closest place is 3 hours away and they have a 2 month waiting list. but mainly, i am really starting to like the idea of a 1" 8 track machine...

so let me get the demagging procedure right first. the instructions on the han-d-mag say to
1) turn off tape deck (what kind of idiot would leave the deck on???)
2)plug in 3' away, then move in and demag each part in a circular motion for 15-20 sec then move back before unplugging.

so, should you demag a single part for 15-20 sec then move back, and then come back in and do the next part? or do you stay "in" and demag all parts and the move back? i started on the right side and then demagged everything from R to L to the opposite side, then moved back. am i overanalyzing this?
--doris

[The Ghost of FM]

Doris,

When I de-mag my machines, I move in the wand, slowly in a circular motion the wand toward each head and guide and pull away from each part in the reverse direction about a foot and move back in to the next part in the transport's heads and guides.

It's an awkward, tedious procedure that requires your full and undivided attention.

I normally start from a 6 foot distance when I first plug in the demagnetizer and pull it slowly away a full 6 feet when I turn it off. Three feet should be ok too but, I am paranoid about it so, I use the six foot standard to be sure to avoid any problems.

Doing this procedure repeatedly, will remove all but the most permanently magnetized fields from the offending parts.

What you could try as a simple test is take a paper-clip and move it slowly near the parts in question and see if the clip is magnetically attracted to any of the parts you have just finished doing and if you see it wanting to stick to that part, you'll know which parts to work on some more with another de-mag session.

If after a few attempts, you still have the clip wanting to stick, those parts will have to be replaced.

As for getting a one inch, eight track recorder, that would be a wonderful format to move up to as the sound will become fuller and slightly quieter with regards to hiss.

Let us know how the progress is coming and we'll go from there.

Cheers!

[kristian]

Different demagging wands have different strengths. When you screwed up with the radioshack wand it is hard for that strength wand to correct the damage. If you jump up to a higher strength things get more volatile. definitely use the 6 foot rule, and when coming close to parts don't let the stronger magnet pull itself onto the part, you will refry. But that sounds like it could be worth a try. It sometimes works depending on what damage has occured.

[Derek Verner]

Certainly, degaussing with the power on will overpower the electronics, but how does it magnetize any part of the tape path? Done as described, it can only DEmagnetize these parts.

[The Ghost of FM]

Originally posted by Derek Verner
Certainly, degaussing with the power on will overpower the electronics, but how does it magnetize any part of the tape path? Done as described, it can only DEmagnetize these parts.

It hasn't been determined that this has happened in this case.

I have read in my TASCAM manuals that if you turn on the wand too close to the recorder, that this action could put a permanent magnetic charge onto the metal parts in the vicinity of where the wand was switched on.

The paper clip test was a suggestion as a simple test just to make sure nothing weird was going on there on the heads and guide posts.

Cheers!

[Vintage TX]

If you turn the demagnetizer on and get close to the head, a mistake with releasing the button when you are demagnetizing the magnetism will go to heads, tapeguides etc...
Not a good thing.
The worse is what Doris did, with the power on... that destroys the whole thing instead.
Be very careful when playing with demagnetizers.
Head replacements is not cheap..
Sorry Doris.

[Derek Verner]

Switching the wand On close to the heads is not as serious as switching it OFF too close to the heads (or other parts of the tape path). The wand works by supplying an alternating magnetic field that aligns the magnetinc domains in the material being demagged. first with one polarity, then with the other. As you move the wand away the field gets weaker and weaker until it can no longer reverse the polarities of all the domains. Some of them remain randomly oriented.

Due to inductive reactance the wand switches ON slowly and switches OFF quickly. The lines of force in the wand collapse faster than they build up, producing a spike.

In addition, when turned ON, the wand can only magnetize to its maximum strength. This strength is just as strong when the current in the wand reverses polarity so that the turn on effect is quickly neutralized.

The bottom line is that, you may have damaged a transistor or two, but your heads can be saved by continually demaggaging them. It is not possible to permanantly magnetize them or to burn out the coils by inducing too high a current through them with a degaussing wand.

[regebro]

Originally posted by Derek Verner
Certainly, degaussing with the power on will overpower the electronics, but how does it magnetize any part of the tape path?

It doesn't. People are thinking of another problem: Turning the demagger on or off close to the heads. THAT may magnetize the path.


I seriously doubt that you can check magnetization by getting paper clips to be attracted to the head. If you have that high magnetization in the tape path, you probably need to junk it. The magnetization that a demagger removes is much more subtle than that.



I think this thread is a good reason why NOT to demag very often. Most modern tape machines does not magnetize easily, and don't need demagging at all. So demagging to be safe is a good thing, maybe a couple of times per year. More often if you are professional, of course, and use the tape machine every day.

[Vintage TX]

If you don't know what you are doing, you should stay away using demagnitizers period.
But I don't agree it doesn't need to have it done.
When using it and the ON button is pressed, don't let go until you are at least 4-5 feet away from the deck, and of course no tapes close by...
Also some tiny toy demagnetizers can't take more use then 1 minute before they collapse.
So be careful what brand you use and read the instructions.
PLUS watch that ON button and always power OFF on the deck.
Once a year is not enough, every 30-40 hours of use is common.
At higher speed like 15 ips more often compare to slower speed.

[regebro]

Yes, but the every 30-40 hours of use is a number derived from the needs of older tape decks, manufactured in the 40s, 50s and 60s. Newer tape decks are less suspectible to magnetization, and therefore do not need demagging as often.

This is all religion, and as in all religion, old practices remain even though they no longer make sense.

Here is an interesting read on the topic, btw.
http://www.interstage.dk/Sider/Produ...tizing_not.pdf
It includes a way to figure out if you need to demagnietize. Unfortunately, it's very cumbersome, so it's easier to just demagnetize.

My recommendation is to demagnetize when you do your big spring/fall cleanings in the studio.

[doris]

this turned into a nice discussion. regardless of how much i have learned here, i am going to have a hard time plugging the han-d-mag in again any time soon--especially if i get a new machine! i can intellectualize it all i want, but it will still scare the crap out of me next time. for example: obviously i did a no-no, but how do i REALLY know the demagger isn't f'd up??? maybe i SHOULD pray to the god of demagnetization next time...
--doris

[The Ghost of FM]

You could test out your Han-d-mag by trying it on a magnetized screwdriver tip that normally picks up a screw. Use the wand on it to see if it can rid the screwdriver of it's power.

Besides that, though, the fact that you fried a few parts in the circuitry is testament enough that it indeed works!

Good luck with the estimate from the shop if you are still planning that route.

Cheers!

[doris]

Thanks Ghost! A plan is in the works. I'll report back when I get somewhere with this.
--doris

[DigitalSmigital]

The beauty of analog recording over digital is brought into sharp relief in this thread. Sure, they get to defrag and edit regestries, but we actually dance around the altar waving a magic wand. I for one, am completely hooked.

Originally posted by Derek Verner
The wand works by supplying an alternating magnetic field that aligns the magnetinc domains in the material being demagged. first with one polarity, then with the other.

If you want us to take what you say seriously...blah, blah, blah. Practice what you preach, and don't sit with your back to the door.

Originally posted by regebro

This is all religion, and as in all religion, old practices remain even though they no longer make sense.

Blaspheme! The Big Dog at the old TASCAM bbs, Larry Robinson, had us demagging before every recording session . Now, there's a shaman who knows the value of a stylized pagan ritual...