Set the default math font back to the original

Question

Long time lurker, first time poster, but my time has come.

I highly suspect the answer to my question is easy, but I can't find how to solve my problem. I'm typesetting my Ph.D. thesis and I'm using a template built by some students of my University. The default fonts of this template were changed to resemble a document made in Microsoft Word, for reasons I really don't comprehend (the default LaTeX font is so beautiful!).

I managed to revert the text back from Times New Roman to the default Computer modern Roman with a command

\renewcommand*\rmdefault{cmr}

But I couldn't find how to revert the math font to the default. Currently, for example, my equations are like this:

While I want them to be like this:

In my document I renamed the \vec{} command to produce boldface text instead of putting the small arrow. The second figure was produced with an online LaTeX formula editor because I just wanted a figure with the default math font.

The differences on both fonts are noted mainly in the greek letter tau and the roman letter u.

A MWE is as follows, without the several included packages. None of them are related to fonts, except amsmath is almost a default. The font is defined somewhere on the class ufscThesis.cls, which I'm not comfortable editing. I suspect it is possible to, on the document, globally redefine the math font in the same way I redefined the text font to CMR without touching on the class file.

\begin{document}
   \begin{equation}
       \rho\Delta\vec{u}=\vec{F}\tau
   \end{equation}
\end{document}

How do I do it?

Answer 1

I solved it!

The class I'm using just configures a document according to ABNT rules (a Brazilian normatization organ), based on a LaTeX package called ABNTex (aptly named for ABsurd Norms for Tex). Since I found no mentions whatsoever about fonts on the class ufscThesis.cls, neither the modifications I did to force the default font worked, I decided to take a look on the class abnt.cls. There I found these lines:

%%%%%%    Opcao de fonte Times como romano default

\ifthenelse{\boolean{ABNTtimesfont}}% if `times'option enabled...
 {\IfFileExists{mathptmx.sty}%  try `mathptmx' first
   {\RequirePackage{mathptmx}}% 
    {\IfFileExists{mathptm.sty}% if not installed, try `mathptm'
       {\RequirePackage{mathptm}}%
       {\IfFileExists{times.sty} % 
         {\RequirePackage{times}}%
         {\renewcommand{\rmdefault}{cmr}}%
       }%
    }%
  \IfFileExists{helvet.sty}% including also Helvetica as sans serif.
    {\RequirePackage{helvet}}%
    {\IfFileExists{helvetic.sty}%
       {\RequirePackage{helvetic}}%
       {\renewcommand{\rmdefault}{phv}}%
    }%
  }%

It was just a matter of commenting this small snippet an, voilà, sexy beautiful equations again!

Thanks for the help!!