If the TX is burnt up, is one of your diodes shorted? The TX is the most expensive part but MPJA.com is in Fl. and has some reasonably priced ones. I just tore into an annunciator power supply that was clearing 7A slo-blos on Friday. It was just a full wave center tap, unfiltered supply as you described but with 1N2129A 100V, 60A stud mount rectifiers. One was shorted. The supply seems like overkill for the size of the annunciator.