My school has a LED scrolling display board from long ago in the main lobby. When I flip the power switch, it turns on and starts displaying zzzzzzzzzzz... There's a connector on the outside (2x10 pins, see picture) that doesn't match up with anything I can find at school or online. The connector

I have done some testing with a multimeter. Labeling the top left pin 1, the top right 2, second to top left 3, second to top right 4, and so on, I have done some testing. Pin 1 is connected to pin 2 with a resistance of about 3.7 ohms, while pin 2 is connected to pins 4, 6, 8, etc. (all the pins on the right side) with almost no resistance. 1-2 have a voltage drop of about 4.7 V when the thing is on, and 1 is positive while 2 is negative. All other pins next to each other (5-6, 7-8, etc.) also have a voltage drop, although it is a little smaller. 3-4 has a voltage drop of 0 in either direction.

This testing leads me to believe that the pins on the left are connected to power while the pins on the right are connected to ground, but I am not sure of this. Even if that was true, where do I go next? How can I go from displaying zs to being able to input a message for display?

For reference, the only company name anywhere on the board is "The High School Source Property of MarketSource Corporation 10 Abeel Road Cranbury, NJ 08512 (800) 877-4401"

The board is a matrix of LEDs about 2 meters long and 6 LEDs wide.

Thank you so much for your help. Let me know if you need any more information.

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    \$\begingroup\$ Not much can be said looking at the connector only. Since there is some scrolling text, I would guess there is some non-trivial controller inside. \$\endgroup\$ – Eugene Sh. Dec 17 '18 at 16:25
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    \$\begingroup\$ Try calling MarketSource Corporation. If they answer the phone, see if they have any info. What connects to the other end of the 20-pin cable? \$\endgroup\$ – CrossRoads Dec 17 '18 at 16:28
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    \$\begingroup\$ Open it. That's the only way to be sure. \$\endgroup\$ – Passerby Dec 17 '18 at 16:44
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    \$\begingroup\$ Welcome to EE.SE! This appears to be a reverse engineering, modification, or repair question. Please be aware that such questions must involve specific troubleshooting steps and demonstrate a good understanding of the underlying design of the device being discussed, so that you can ask specific, focused questions that can be answered concisely. Otherwise, the question is far too broad. More information can be found here: Is asking how to fix a faulty circuit on topic?. \$\endgroup\$ – Dave Tweed Dec 17 '18 at 17:11
  • \$\begingroup\$ Call 800-877-4401 and ask for technical support. \$\endgroup\$ – Misunderstood Dec 19 '18 at 3:42

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