This summer I had purchased a LED sign. On a closer observation I discovered that I cannot read the model number. The sign contains two LED circuitboards with "DR-14830" on them. Since I have been modifing LED signs to work with the Arduino for over 12 years now, this sign was another challenge for me to figure out. It uses 74LS164 shift registers with ULN2003 drivers for the columns. The rows are selected by a 74LS164 then a 74LS138 then a ULN2003 then TIP122 power transistors. The power transistors go to the anodes of the LED arrays. The row selecting 74LS164 was in the chain of shift registers so I removed it to make the software simpler to write.
This is a picture of the back panel, as you can see the model number is not readable.
After a couple hours of troubleshooting the sign started working. I will eventually upload the software once I get it fine tuned.