I have a Macbook Air running OS X yosemite 10.10.5 and its sat on a home network which has a Windows 7 PC which hosts 2 printers, a HP and a Kyrocea.
Ive gone into the mac and hit the apple symbol and then select system preferences and select printers and scanners. Click on Windows and then I see the PC which has the two printers on it. When I click the pc name, it prompts me for the username/password for the windows PC and I put them in. It takes about 5 minutes before it eventually times out and reports there is a problem with the username/password. Ive double checked the credentials and no they are correct, I even turned off the windows PC firewall to see if that makes any difference but alas its the same.