The +5 Volt section is the main power supply for the whole pinball machine. This section supplies the voltage to all of the IC's on every circuit board, including the processor chip. With out this section, the machine will not operate! This section is also becoming one of the more regular failures on the Data East Power Supplies... If you find you have around +3.5 Volts when you should have +5 Volts, then this is where you want to be looking...
Below is the +5 Volt section of the 520-5047-01 and 520-5047-02 boards...
1) If you have followed the +12 and -12 Volt part of this guide, then you will have already replaced the Bridge Rectifier, which leads us on to the next main parts...
2) The Voltage Sense Capacitor (C2 - 100uF 25V). This Capacitor is the most common part to leak on the whole Power Supply. Once this Capacitor leaks, you will find that you only have approx +3.5Volts on the CPU board, when you should have +5Volts. This cap should be replaced with a 100uF 35V capacitor, and have any leakage cleaned up.
3) Once the C2 cap has been replaced, make sure you replace the diodes at D2 and D3 (use 1N4007 diodes for this). These are part of the AC voltage sense circuit and should be replaced. Also replace the capacitor C3 (47uf 63V) as it is also part of the AC voltage sense circuit. The AC voltage circuit is needed for the LM723 IC to function properly.
4) The next major part in need of replacing is the 2N6057 transistor. This is best replaced with a 2N6059 transistor as it has a higher voltage and current rating. This transistor provides the "constant current" supply for the +5 Volts and is governed buy the LM723 regulator IC. It needs to be in top working order for the Power Supply to provide the +5 Volts to all the IC's.
5) The next part to replace is the LM723 Voltage Regulator IC. Many people recommend not replacing this IC as it does not cause many problems... This is relatively true, but the LM723 can oscillate causing many problems within the +5 Volt line. I personally do replace this part for that reason... It is an old chip based on old technology...
6) Finally, the Output capacitor (C7 - 330uf 25V) should be replaced. This is not 100% necessary, but is a good precaution. Replace this capacitor with a 330uF 35V cap.
Next will be the High Voltage Section...
