|PP7A is a switching power supply located in a metal box on the left side of the monitor. This picture shows the cocktail table version of Radar Scope and the arrow points to the PP7A located behind the coin box.|
|The 6P ESS and 7P SOU plugs are on the back side of the box. Seen from the solder side, you will have the two GND pins of the 6P ESS on the left as in this picture|
On the top of the plug you can check voltages by applying the probe during attract mode.
In a working game they were, for example: 4.83 V (low by 3.4%) / -5.07 V / 12.04 V / 23.33 V
If you have a defective power supply and you cannot repair it you can replace it by using two switching power supplies, one for the +5 and the +12 volts and another for -5 Volts.
The reason for the necessity of two supplies is that the CLK board with its ECL
logic draws a large current of several amperes at -5V.
The original power supply has the following specs
|+5 V DC||up to 7.5 A|
|-5 V DC||up to 6.5 A|
|+12 V DC||up to 100 mA|
|+24 V DC||up to 200 mA|
The 24 Volts are being used for the game counter and can be omitted if necessary
A very good replacement for the PP7A power supply are two PC power supply units from old PC's. For example, I have used two identical Magnetek power supplies which are too weak for modern PC's (having only 65 W per unit) But they can be used as a Nintendo replacement PP7A without problems
You will have to wire them in the following way:
|This is the edge of a TRS-02-ESS board, showing the P2 POWER IN connector from the component side. PINS 1 and 2 are GND, 3 is +12V, 4 and 5 are +5V, 6 is -5V. See also in the video section.|
|Backside of the same board. The jumper cable on the solder side is on PIN 3 (+12V). Note that in the schematics (PDF) of the ESS board the pins are numbered in mirrored fashion (which is an error).|