El Capitan - Arduino IDE serial port problems

Using Arduino IDE 1.x
18

ardn00bo:
Followed the hookup in this link Gammon Forum : Electronics : Microprocessors : Atmega bootloader programmer

Programmer: Arduino as ISP
Tools->Burn Bootloader
Result:
“avrdude: Yikes! Invalid device signature.
Double check connections and try again, or use -F to override
this check.”

Nick Gammon's instructions don't say to use >Burn Bootloader. You only followed his hookup, not all of his method.

I followed his instructions last week to burn new bootloaders onto 2 x ATMega328P chips, and used his sketch in an Arduino UNO to burn the bootloader onto new chips on a breadboard, not the Arduino IDE's >Burn Bootloader.
His sketch to burn a bootloader is "Atmega_Board_Programmer". Note that you need to download his whole directory, because it also contains the actual bootloader code in *.h files.

Believe my connection are the same as in the link. I do not have a 10uF Cap between the reset and ground like some links indicate.

I didn't need a cap either, but did you try one? You should be able to use your working UNO clone to do the burning, running Nick's sketch and the connections he provided.

Can I update the boot loader with just a mac and the clone board?

Yes, if you can load Nick's sketch onto the clone UNO, as I just said above. You can bypass the "Arduino as ISP" and "Burn Bootloader" in the IDE.

  1. Official Arduino Mega 2560 board
    Not detected. What driver should this use? FTDI driver?

No driver needed. After a little reading on the Mega, (I only have UNOs), I found this, relating to the (original) Arduino ATMega2560 R3:-

Because the board features Atmel's own USB-to-Serial chip instead of an FTDI chip, there is no need for drivers under Linux or Mac (only an .inf file included with the Arduino IDE is required for Windows), and you have the ability to make the board show up as various types of devices.

So if you're on Mac, and have a genuine R3 Mega, you shouldn't need additional drivers. (I guess that means you have other problems, since the El Capitan issue in this thread relates to the (insecure) CH340G drivers.)