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Yes you can, but you need to have an understanding of what is involved. I have resolved most issues with mine with the following modifications much of it was gleaned here. The issues with MTH engines can be resolved with an 18v light bulb in the circuit.

As built, the U terminals are the outputs. A & B are common. Simply wiring the center rail to the “U” post and the outside rails to “A” will result in the bell and whistle functions being reversed. The fused transformer lead should be connected into the board termination point labeled “GND” ”. The black wires should go to the point marked AC+ AC_ and “the red wires of this set of four should be moved to the outer termination points”.

Now that the outputs were switched, the whistle button controlled the bell and vice versa. Using Dale Manquen’s schematic I was able to switch this. With through hole resistors I ran the R1 button point to pin 14 and R2 button point to pin 12 of the microprocessor. No damage was done to the board I just went from resistor pad to resistor pad. I put sleeving on the resistor leads. The whistle button now activates the whistle and the bell button the bell. The horn/whistle responds immediately but “holds” about 3-4 seconds. The bell button has to be “pressed” about 3 seconds to engage or turn off the bell.

The last item to take care of was the cooling. Dale Manquen talked about the fan running off of positive half of the AC waveform. Turning the diode around to the marked direction on the board and switching the fan leads would help reduce the DC in the transformer core. I followed this coupled with the addition of the 100mfd capacitor that Don Holdaway suggested. The fan is now running at 10.9 volts and much much noisier now. The other thing I did to improve the cooling was to break out the internal ribs of the cooling vents. I did this with a small pair of side cutters. From the outside of the case there really isn’t much of a change except you can see inside the unit.

I have been fond of this transformer as it is self-contained. Now that I have made the above changes all of the black wires to the board are in the same point. I agree with Frank Maguire in his post where he thought the transformer was designed here but there changes made along the way. This is somewhat confirmed by Don Holdaway. The only additional thing needed is to have a light bulb in the circuit if you are running PS2. This is a lot to have to change to fix an otherwise nice transformer.

                   

 

 

 Steve

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OGR Publishing, Inc., 1310 Eastside Centre Ct, Suite 6, Mountain Home, AR 72653
800-980-OGRR (6477)
www.ogaugerr.com

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