The original selenium rectifier may be OK. If not, replace it with a 1N4007 diode and a series power resistor. You can compute the resistor value and power rating by adding up the current from the schematic and using ohm's law to achieve the voltage drop on the schematic. Verify voltages after replacement.
Doug
: Just purchased Trans-Oceanic H500, what do I need to do to modify the 50A1 and the selenium rectifier..Help