Hi everybody
This is my 1st post so be easy on me. 1st of all I would like to say how impressed Iam with this site. The professional courtesy that everyone shows on this site is awsome. It is a pleasure to read the threads and posts and how everyone helps everyone out. My hat is off to all of you.
I have been in the video production business for 29 years now (and always tape based).
I just decided to move up to the AVCHD format. What an eye opener. I just recieved my 1st HMC-40 last week. I have pertty much figured out the basics. I use Final Cut Pro for editing (started with 1.25 in 1999) now I have 7.0. and still learning. I found a site that shows how to log and transfer files to my mac. In the audio video settings i set the SEQUENCE PRESET to Apple Prores 422 (HQ) 1920 X 1080 60I 48 khz. In the CAPTURE PRESET HDV-Apple prores 422 (HQ). DEVICE CONTROL to Non-control device. I log and transfered some clips and droped them on the time line and did some minor editing.
This is my problem. I use a 23" gateway monitor for my Final Cut editing, I also out put through a fire wire cable to a Sony DSR-20 deck and out of there to a Sony 37" monitor.
This way I can edit and at the same time on the Sony I can view the finished movie as it is being completed. Been doing this for years. Now when I play the time line back as it comes through the firewire the video is all broken up and cant understand the audio. I went back into the video settings in Final Cut and changed the playback settings to Digital Cinema Desktop Preview-Main and audi to Default. When I did this nothing came out of the firewire cable and my Final Cut monitor completely changed. It changed to the full movie and no Final Cut WINDOWS TO EDIT WITH. I had to go back into the settings and change the video playback setting back to Apple Firewire NTSC (720 X 480) PLEASE WHAT AM I DOING WRONG.
Thank you.

Your workflow is right up to a point and from there you need to move into the HD world.

You should transcode AVCHD to ProRes to work in FCP. While technically you can edit AVCHD in FCP timeline, it is so slow and requires so much horsepower that transcoding is the best thing.

Now, however, you are in an HD world and need to monitor HD.

Thus, you need to go out of FCP through another device.

Presuming you're dealing on a MacPro, you could always use a Decklink Intensity ($199) and output HDMI to HDMI compatible monitor.

Next-- Matrox MXO - ($895). External device on 2nd DVI port of your video card and from there monitor to a 23 or 24" computer display.

Then you can go the capture card route-- whether products from AJA, Decklink or Matrox to output to SDI or HDMI monitor.

What you are trying to do is push an HD signal out via firewire to an SD deck. Can't do that.

Remember that your camera is in many regards the smallest part of your HD investment. Monitoring is a significant part of the post production process. You have three general ways of achieving this in ascending order of price/quality.

Thank you Ned for your return.
I guess i forgot to say that i did transcode my clips to ProRes in Final Cut and than i did my editing.
I do have a Mac Pro duel intel.
On my card on the back i have 2 monitor outputs. one goes to my Final Cut monitor and the other is not being used.
My preview monitor, which I watch my finished movie on is a Sony 37" HD 1080. It has
3 HDMI inputs, a PC input S-Video, Componet ect ect.
If I am reading your response right, I would come out of the 2nd computer output on my card into the Decklink and than HDMI OUT TO MY 37" monitor HDMI IN.
Iam not sure I understand the Matrox MXO external device or the capture card route.
Thank you for your understanding.