Author Topic: Malfunctioning magtek stripe reader: measure crystal resonator easily?  (Read 3294 times)

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Offline Erwin RiedTopic starter

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Hi,

I was trying to use an old ps2 magtek stripe reader, this one:


It was working years ago, but after that I just stored the device. Now the red led stays lit and the reader sings a little song (probably reporting a failure: low tone, high, high, low, high, high, ...) I checked inside and the only thing strange is a rusted crystal labelled MMD160AK (I guess is 16 mhz?). Is there a way to quickly check this?



I had several crystals, and using a 16 mhz the song continues but sometimes the led just stays red, no song.

Any hint? Is not sending anything thru the ps2 port, only 0xFF bytes when connecting.
My website: http://ried.cl
 

Offline HalfSpace

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Hi Erwin Ried,

If it sings the same tune with a 16MHz crystal I think you have picked the correct frequency.

Does the reader have an optical sensor to detect a card is present or is it completely magnetic sensing?

The card sensor may not be working and the reader may think it has a card in it when you power it up.

HalfSpace  :)
"He who asks a question is a fool for five minutes; he who does not ask a question remains a fool forever."
 

Offline Erwin RiedTopic starter

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Hi HalfSpace

Right! it was a 16 mhz. Tested different values and the song changed :D no insertion sensor, the reader made a beep after a card was slided but that was probably due the magnetic header readout (always powered?)
My website: http://ried.cl
 

Offline HalfSpace

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Hi Erwin Ried,

Are you running the reader from a PC or a microprocessor project?

The reader may require handshake data between the PC (or project) and itself to start working.

Here is a link for the PS/2 protocol which may help.
http://www.computer-engineering.org/ps2protocol/

When the reader was working years ago what did you run it on?

HalfSpace  :)
"He who asks a question is a fool for five minutes; he who does not ask a question remains a fool forever."
 

Offline Erwin RiedTopic starter

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hi again,  both times was from an arduino. Same code. I later tried it on the computer,  same little song. May the rom is corrupted or something like that after so many years stored?
My website: http://ried.cl
 

Offline HalfSpace

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Hi Erwin Ried,

Rom chips rarely fail. Can you post some pictures of the PCBs?

HalfSpace  :)
"He who asks a question is a fool for five minutes; he who does not ask a question remains a fool forever."
 

Offline Erwin RiedTopic starter

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Hi, here are the photos:

The board with most of the chips is the main one, I removed that ROM and song stops, so probably that's doing something :D. I broke a buzzer (plastic part in the lower part) and removed the crystal:




Very few stuff to see, and the only thing that seemed damaged was the crystal.
My website: http://ried.cl
 

Offline HalfSpace

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Hi Erwin Ried,

The EEprom (24C04A) looks like it has been re-soldered, has this been removed or replaced?

Operation manual for the Magtec mini.
http://www.magtek.com/documentation/public/99875123-11.03.pdf

The link below has some documentation on Magtec readers.
http://stripesnoop.sourceforge.net/devel/index.html

This PDF has data on the Magtec analog head reader IC in appendix B.
http://stripesnoop.sourceforge.net/devel/magtek-io.pdf

HalfSpace  :)
"He who asks a question is a fool for five minutes; he who does not ask a question remains a fool forever."
 

Offline Erwin RiedTopic starter

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Thanks. I'll take a look at these links. Yes, I resoldered it because there was some corrosion from the crystal,  just to be sure.
My website: http://ried.cl
 


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