Malfunctioning magtek stripe reader: measure crystal resonator easily? - Page 1
Forum section: electronics / beginners

author: Erwin Ried
author_rank: Regular Contributor
timestamp: May 05, 2014, 03:26:50 am
content: 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.

author: HalfSpace
author_rank: Regular Contributor
timestamp: May 05, 2014, 11:55:58 pm
content: 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

author: Erwin Ried
author_rank: Regular Contributor
timestamp: May 06, 2014, 07:29:12 am
content: Hi HalfSpaceRight! it was a 16 mhz. Tested different values and the song changedno insertion sensor, the reader made a beep after a card was slided but that was probably due the magnetic header readout (always powered?)

author: HalfSpace
author_rank: Regular Contributor
timestamp: May 07, 2014, 12:05:30 am
content: 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

author: Erwin Ried
author_rank: Regular Contributor
timestamp: May 14, 2014, 03:54:27 pm
content: 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?

author: HalfSpace
author_rank: Regular Contributor
timestamp: May 14, 2014, 10:07:02 pm
content: Hi Erwin Ried,Rom chips rarely fail. Can you post some pictures of the PCBs?HalfSpace

author: Erwin Ried
author_rank: Regular Contributor
timestamp: May 18, 2014, 11:14:42 pm
content: 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. 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.

author: HalfSpace
author_rank: Regular Contributor
timestamp: May 20, 2014, 12:00:20 am
content: 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.pdfThe link below has some documentation on Magtec readers.http://stripesnoop.sourceforge.net/devel/index.htmlThis PDF has data on the Magtec analog head reader IC in appendix B.http://stripesnoop.sourceforge.net/devel/magtek-io.pdfHalfSpace

author: Erwin Ried
author_rank: Regular Contributor
timestamp: May 20, 2014, 03:09:07 pm
content: 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.