Power supply for ultra linear stereo amplifier. One prong of the line plug goes to the bottom of the primaries of three transformers. The other prong of the plug goes through a 4 amp slow blow fuse then a single pole single throw switch then to the tops of all three primaries. One of the transformers is a Hammond model 278CX, 800 volt CT at 465 mA. The 6.3 volt heater winding is not used. A .002 u f 6 kV cap connects across the entire high voltage winding. One side of this winding goes to the anode of a 1N4007 diode. The cathode connects to the anode of another 1N4007. The other side of the high voltage winding goes through two 1N4007s in a similar manner. The two cathodes of the two diodes farthest from the winding connect together and to the positive side of a 100 u f 450 volt cap. There is a 150 k ohm 1 watt res in parallel with this cap. The negative side of the cap goes to the positive side of another 100 u f 450 volt cap which also has a 150 k ohm 1 watt res in parallel with it. The negative end of the second cap and its resistor go to one side of a filter choke which is labeled 10 Henry 500 mA, Hammond 193Q. The other side of the filter choke goes to B minus. The two diode cathodes also connect to another set of 100 u f 450 v caps and 150 k ohm 1 watt resistors as previously described. The negative end of the lower cap goes to B minus. This places the filter choke in the negative lead instead of the positive one as you may be accustomed to seeing it. The point where the diode cathodes and two sets of capacitors connect together goes to a connection point labeled B plus 1. B plus 1 also goes to one end of a 4.7 k ohm 5 watt resistor. The other end goes to a point labeled B plus 2. B plus 2 goes to the cathode of a 100 volt 5 watt zener diode. The anode goes to the cathode of another 100 volt zener. The anode of this zener goes to the cathode of another 100 volt zener. The anode of this zener goes to the cathode of a fourth 100 volt zener. The anode of this last zener goes to B minus. There is a legend giving information about the 4 zener diodes. It reads, quote, 100 volt = 1N5378B. End quote. B plus 2 also goes to the positive end of a 100 u f 450 V cap. The negative end goes to B minus. B plus 2 goes through a 22 k ohm half watt resistor to B plus 3. B plus 3 goes to the positive end of another 100 u f 450 v cap. The negative end goes to B minus. There is a chart on the diagram which gives information about B plus 1. It lists various values of current and the voltage produced at that current. The values are; 0 mA, 620 volts. 100 mA, 586 volts. 200 mA, 568 volts. 300 mA, 551 volts. 400 mA, 535 volts. 500 mA, 522 volts. 600 mA, 508 volts. The second transformer is a Hammond 167U6 which is 6.3 volt @ 16 amps. The secondary center tap goes through a 10 meg ohm resistor to the chassis. The ends go to two connection points labeled heaters. The other transformer is a Hammond 262E6 which is a 120 volt 85 mA unit. There is a .002 mike 6 kV cap across the 120 volt secondary. The ends of the secondary go to the AC inputs, the two points where anode and cathode connect together, of a diode bridge. It can be a bridge unit or made up of individual 1N4003 diodes. The positive output, cathodes, goes to C plus. The negative output, anodes, goes to the negative end of a 47 u f 250 v cap. The positive end goes to C plus. The negative output of the bridge also goes to one end of a 15 k ohm 1 watt resistor. The other end goes to the anode of a zener diode which is labeled 1N5378B, 100 volt 5 watt. The cathode goes to C plus. The zener diode anode goes to a 3.3 k ohm res. The other end goes to the negative end of a 47 u f 150 v cap. The positive end goes to C plus. The junction of the 3.3 k ohm resistor and capacitor goes to a point labeled C minus. C plus is connected to the chassis through a 100 k ohm resistor. There is an 8 pin octal socket mounted on the chassis. This looks like a regular tube socket. An octal plug on the end of the power cable will plug in here. The pins of the socket are connected as follows. Pin 1 to one end of the heater transformer secondary. Pin 2 to C minus. Pin 3 to C plus. Pin 4 to B plus 3. Pin 5 to B plus 2. Pin 6 to B plus 1 Pin 7 to B minus and the Chassis. Pin 8 to the other side of the heater transformer secondary. End verbal description.
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