Q: reset my time capsule and connect it directly to imac only for back up

Your little comment in the profile.. it used to work before Mavericks.. might be better to fix it and use it still as part of your network. The problem is the TC is a purely network device.. It is not at all easy to use stand alone. You cannot connect directly to it by USB. It really has to be part of the network.

I have used them plugged in by ethernet to a computer that connected to the internet by wireless. That is messy to setup but works. I will need some info to do it.

How does the iMac connect to the network.. and what IP does it get??

From that I can give you setup but with due warning, this may still have network issues as those bugs are in Mavericks. And you could save yourself the effort and just try to get it working as part of the existing network.

OR.. IMHO much better solution in this case. For desktop type computer like iMac.. plug in a USB drive.. Or FW800 or even thunderbolt if you have need for real speed. Thunderbolt>USB3>FW800>USB2. Price wise.. USB3 is now same price as USB2 so that is the best choice if your Mac has USB3 ports. Thunderbolt is still very expensive. FW800 is better than USB2 but is a dead duck.. Nothing you buy will be useful as the port is being phased out. 

But even USB2 will work faster, and be more reliable than a TC.

My other suggestion then is to use CCC or SuperDuper and keep Time Machine as a secondary backup for incrementals. You can produce easily a fully bootable backup drive using CCC. Superduper I heard had issues but that might be fixed now. A bootable backup means if you have a disk failure simply boot the computer from the backup. It is hugely superior method. TM can also continue to be used as it works well for incrementals and restoring applications if that becomes necessary.

Just indicate what you want and we can suggest a way forward or give details on the fix with Time Capsule.