I really appreciate the input. I did a freewheeling bench test. With 18 volts from the transformer, the engine seems to be drawing about 3.8 ma ( if I am reading this correctly). Rectifier gets really hot.Johnacton, the pictures are helpful. The bottom one with the BR on the topside is the one that I have.I am guessing that I did the upgrade about 10 years ago, so it may be an older board as you suggest. The engine is a two can motor SD 45, originally PS 1.
Like everyone else, all my more recent TMCC upgrades are ERR. I may use this one as a learning experience to see if I can replace the triacs. One more question, is there a way to test the "diode in the bridge"? And just for clarification is the diode integral to the bridge or upstream/downstream in the circuit. Thanks for all the help.