I recommend a CraftyMech test pattern generator.
I have one of those, it's fantastic for testing if monitors work or have any apparent problems but I wouldn't use it for calibration.
A good example is my Revenge from Mars cab. the reds and blues were really dim the image was terribly washed out and had a green tinge to it and was mis aligned on the screen. brightness and alignment pots were maxed out. I pulled and capped the chassis and it made ZERO difference. I then hooked up the test pattern generator and the image was flawless... perfect color, perfect alignment etc. I went back to to the original RFM board and the image was all screwed up again. Put in a new video cable and still not change (this uses a PC so the signal is coming right from the video card, it's 240P over VGA)
I went through the calibration process outlined in the ArcadeOtaku link above and got it looking fantastic except for alignment. Ended up having to put in a new pot with a wider adjustment range to get the picture aligned.
So now the picture is flawless with the original hardware but looks like total dog shit when using the TPG... but guess what. I don't play games on the TPG so how it looks on that is irrelevant.
This is obviously an extreme case but monitors react differently with different boards attached, so for dedicated cabs you really need to calibrate using the PCB for that cab. For cabs where you're switching boards, try to use whatever board you'll be Playing most often, and then test out any problem boards to see if you need to make any "compromises" to get a decent looking picture across the different boards.
Well, you can use a mirror so you dont have to be running around the cab to look at the image every time you adjust it
This. I have a home built tool for this. I went to Walmart, found a good sized cheap hand mirror like this:
then a cheap adjustable clamp-lamp ( a large strong but padded clamp is ideal) like this:
I removed the electronics from the lamp and the lamp head and then screwed the handle of the mirror into where the lamp head used to be attached. Now I can clamp the mirror to the side of the cab and adjust it wherever I need it to see the monitor while I'm making adjustments out back.
this cost about ~$15 for the lamp and the mirror and only took a few minutes to put together but I use it every time I adjust a monitor.
I know a lot of other people use large full-length mirrors, as those are easy to prop up so you can see what you're doing, but I find having the mirror close to the monitor makes for a real clear view of the adjustments I'm making.