Pinball Rehab

pinball repair and restoration

Electronic Component Substitution Electronic Component Substitution Hot

Some of the electronic components for repairing pinball games are getting hard to find.  This article provides information on using replacement parts when the original is not available.  I have also listed some components where you can still purchase the original part, but it is best to upgrade to a beefier component.

The following Stern document, Component Cross Reference, provides NTG, ECG and Radio Shack part numbers for commonly used components.  These are not recommended replacements but direct replacements.  In some cases, as noted below, a more robust solution is recommended.


  • 1N5237 Zener diode --  upgrade to 1N4738


  • TIP120, TIP121, TIP122, 2N6045 and SE9302 --  upgrade to TIP102
  • TIP42 -- upgrade to TIP42C
  • 13N10L-- upgrade to IRL530N
  • 22NE10L -- upgrade to IRL540N
  • MPSD02 -- replace with 2N5551
  • MPSD42 -- replace with 2N5401

Resistor Networks

Some of the original resistor networks are getting difficult to find.  Here's a method for replacing SRC's with SR's.

The difference between the two is that SRC's have internal capacitors, which the SR's don't.  You can make the replacement on SRC1-SRC9 because Williams installed C49-C56 (.01uF), which made the capacitors in the resistor network redundant.

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Electronic Component Substitution

Note: Make sure your board has these capacitors installed before proceeding.

Use a 1K x 9R SR bussed resistor network.  This SR will have 10 pins, with pin 1 (the end with the dot) being common.  Pin 1 on the SR should be installed in the original SRC's pin 1 position, which is 5 volts.  Cut off pin 10 on the resistor network since it is not needed with the SR.

Pin 10 on the original SRC provided ground for the capacitors and since we're using an SR, with no capacitors, we don't need, or want, this pin connected.

Integrated Circuits

  • 74LS240 -- substitute with 74HCT240
  • 74XX -- see explanation below

Within the 74XX family (for example, 7402 and 7408) there are a couple of variations used based on the speed of the chip and power consumption.  The 74LS and 74HCT series parts consume less power but are slower. The 74F and 74S series are faster and have high output drive capability but consume far more power.  As a general rule use either 74LSXX  or 74HCTXX on CPU boards and dot matrix controllers, and the 74FXX on driver boards, although you should never use a 74 LS, HC or HCT as a pre-driver for transistors.  In this application you want to use a 74XX, 74FXX, 74SXX or 74ASXX.