It has a hum, I substituted capacitors for all the filter capacitors, replaced the diode. Still hums. The schematic I have found has differences, for example the 1000 ohm resistor is marked 500 ohms and I measured 20 ohms across it, resistors I have never found to go down. The 50C5 shows no pins 3 and 4 on the schematic but there are components connected to it. Ideas?