A two for one...

[Zellie Crescent]

at the Walmart. Iwent into theWalmart near my store and see these 2 craptastic things.

First I'm getting chocolate and doritos, but having trouble deciding on what size bag to get. There is a pregnant lady who looks pretty far along in the same isle as me, and these 3 kids come tearing down the isle like a tornado almost knocking the lady down followed by thier mother. I ask the lady if she was ok and she said yes, then I said "It sucks when people don't know how to raise thier kids right." The pregnat lady smiled at me and I could feel the mother glaring a hole in my back.

Second I finaly have everything I came in for and I'm in the 15 items or less lane and the guy in front of me is taking forever, I had to wait in the express lane for about 20 minutes because every time he swiped his card it wouldn't work. He kept telling her the machine was broken since it wouldn't accept his card, she told him it worked perfectly fine and asked him if he had another method of paying. And 4 cards too, who the hell uses 4 credit cards? He gives up and uses cash, I go after him and paid for my stuff.

[Rapscallion]

The bit that worries me about that last guy is just how much debt he must have.

Rapscallion

[Kogarashi]

Agreed. I don't see the problem in having four cards if you're managing them right. You could have them for various discounts or rewards programs, and so long as you're not overspending them constantly and are instead keeping them paid off, then great.

But when you have four and none of them work....

[UncleImpy]

What I find is more disturbing is that he had four cards he DIDN'T KNOW wouldn't work.

If I have a card that's close to the limit, or that I'm trying to pay down and not use, I...

...wait for it...

...DON'T TRY TO USE IT.

The fact that he was trying to cram the purchase on any card that would work tells me he's not going to be out of trouble anytime soon.

[Shalom]

How do you mean "don't work", though? You can read that two ways. Were the cards coming back as declined, or was the machine just not reading them at all?

One or two cards I could see happening by accident: sometimes people slide two cards in their wallets back-to-back with the stripes touching, which can erase one or both of them, but if all four cards were unreadable, then either the machine's wonky, or he left his wallet too close to a big loudspeaker or an MRI machine or something. (Or someone pulled a prank on him with a bulk tape eraser; has he pissed off any audio technicians lately?)

Oh, a pharmacy tech/cashier at the Chain of Verylarge Stores showed me a neat trick: if you have a card that won't scan, wrap it in a thin plastic bag and swipe through the bag, and you'll sometimes get a good read on it. No idea how this works, it seems counterintuitive, but it does work.

[Andara Bledin]

Oh, a pharmacy tech/cashier at the Chain of Verylarge Stores showed me a neat trick: if you have a card that won't scan, wrap it in a thin plastic bag and swipe through the bag, and you'll sometimes get a good read on it. No idea how this works, it seems counterintuitive, but it does work.

The bag works because it increases the distance between the card and the reader head. Tape will also work, and for the same reason.

The data on the card is magnetized, and the charged particles in the stripe get dragged out of place over time. Eventually, that will cause the data to be corrupted to the point of failure as the magnetic bits are moved to areas where there should be none. When you increase the distance between the read head and the card, those mis-aligned bits tend to be too weak to be read at the increased distance, and the reader can get a clean read from the card as a result.

^-.-^

[dalesys]

The bag works because it increases the distance between the card and the reader head. Tape will also work, and for the same reason....

I'll bulltificate about the physics for a bit. (The magnetized bits don't move... the earth does...)

Magstripe card readers have a read head (just like in a tape recorder) that plays back what's recorded on the stripe.

The magstripe is like a bumpy road: NssssNNssNNsNssNNNNN (094F in one coding). The read head has a gap (just barely visible) that acts like a small wheel rolling along, sensing the "bumps".

When the read head wears, the gap gets wider, so it "reads" a longer section of the magstripe (as if the wheel got bigger) and it has a harder and harder time detecting single bit wide changes.

The tape/plastic works because it moves the magstripe away from the head, which then 'sees' just the peaks, which may be enough of a difference so the code can be read.


(I've replaced a few hundred read heads in card access systems. [Elephant's Child: insatiably curious])

There are other causes for unreadable cards: dirt/goo on the read head, physically damaged magstripe, tilted head, tilted recording, magnetically damaged card, bad moon rising...

[reimero]

There are plenty of reasons for having 4 cards. I, personally, have... ummm... somewhere in that range-ish. It's not a question of extending credit as far as possible so much as a question of financial and rewards management. Not every place takes every type of credit card. I happen to prefer Discover cards, but those aren't accepted everywhere, so it's in my best interests also to hold a different type of card. I also have a card I use almost exclusively for travel expenses, because I need to track that separately.

I've had it happen on a few occasions that my Discover card was declined because the vendor didn't accept Discover, not that I didn't have sufficient balance. You'll almost always have sufficient balance if you pay it off every month.