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    brucek
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DAS Testing...

So I have a DAS Entry station that I just replaced the smashed switch (single button entry station) in my shop, and I would like to be able to test it before going back on site, and I don’t have an EMAP or such.

 What is a technician to do!?

Is there any information about what I should see on the data lines with my scope when I power it up with out an interface?

Does J4 hold any secrets?

Any ideas?

BTW DAP V1.01

Thanks

 

  • (A repair tech once said...) 

    "This is a tough one.  You would need to power up the DAS station with some sort of +12vdc power supply.  +12 on pin 1 of J3 and GROUND on pin 2 of J3.  Without an EMAP you can’t really do much testing.  There are also no self-tests built into the DAS stations.  With the power applied, you should see the LEDs lit up very dimly.  If no communication is present, those LEDs will turn off after a few seconds then turn back on at the same dim level.  They will repeat this process until communication is found.

     

    One thing I check on all DAS stations is the RESET line.  The switch used for the RESET line is the cause of the majority of problems with these stations.  Using the GROUND at J3, I use my Digital Multi-meter to check it.  With a DMM check for +5v at the CATHODE of CR2.  This tells us that our +5v regulator is good.  Next check the ANODE of CR2 for +5v.  This tells us that the switch is OFF.  If you see a lower voltage than +5v, then your switch is probably bad.  I have been removing these switches for prevention.  These are not needed for normal operation and have a tendency to fail after several years.  Switch the RESET switch to on and check for 0V.  "

  • in reply to corey cascio

    Well, I tracked it down to sometimes when I would power it up with 12V it would dim light the LED, then move into the slow flash,no comm, mode.  This, I assume means its alive.

    And sometimes nothing would happen;  the CPU would not run, but V+ is ok.  Even though the RESET measured OK, when I yanked the switch, all the problems seemed to go away.

    So the RESET switch was a good call.

     

    Anyway, I see that when the station is powered up/reset, it just sits listening to the data line.  Is there any way to trick the station to try to send data so one can prove the driver chip is OK?  I would just love a quick way to verify button presses, address switch, LEDs, and driver chip . Maybe an EMAP will just appear one day, and my bench can be complete….and the theatre children will rejoice and there will be love and smiles…and working house lights and….Ok, so I need to deal with a DAS station in shop maybe once every few years....

     

     

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