wjfisherjr, it appears you are not really reading what people are suggesting to you, as you seem to ignore what is being said.
Take for example, the last post of PaulS, where he suggests to you that the Arduino is sending data as binary, not as hexadecimal.
Did you go and look at the ASCII table yet, no, well here is a link for you, ASCII Table ?
I don't know the details of your device and you really haven't provided much to go on.
For example, if you wish to send a number 35 out the serial port for your scoreboard, you will likely need to do the following.
First, realise that the number 35 is made up of two characters, a 3 and a 5.
The number 3 in the ASCII table is 51 decimal, and the number 5 is, you guess it, 53 decimal.
So, if you send using serial.write the value 51 followed by another serial.write with value 53, you may be getting closer.
If in fact you need to send hex, then send the hex codes instead of decimal.
Many years ago, these sort of projects were common place, to work with different serial interfaces.
As Paul_KD7HB suggested to you, you do not need the RS-232 interface together with the RS-232 to current loop converter.
You simply need an opto-coupler set up correctly.
Why not do an online search for digital 20mA current loop circuit ?
It must be your lucky day, here, I did it for you, and this link will tell you much to learn about digital current loops.
As you will notice, there are even simple schematics based on opto-couplers, just as Paul_KD7HB suggested.
Forget the MIDI interface, it may not provide enough current, maybe as low as 5mA, which will not be enough for the scoreboard I think.
Paul - VK7KPA