Symptom: Cheap Squeak sound board blowing fuses.

I had another person send me their Cheap Squeak board from their Spy Hunter pinball machine after it was blowing fuses. Compared to last time, it was much easier to identify where the short was located. Both C10 and C22 capacitors were shorted.

Shorted capacitors.

Tantalum capacitors were used for both C10 and C22, and a variety of other locations on the sound board. Although tantalum capacitors don’t age like aluminum electrolytic capacitors, they have a weakness: they don’t tolerate voltage spikes very well (nor reverse polarity, where they will likely explode).

Both C10 and C22 are located on the unregulated 12 Volt supply.  This supply normally runs a little higher, and since it’s unregulated can have voltage spikes on it.  So if your Cheap Squeak is blowing fuses, replace both of these capacitors.  The original caps were rated at 25 volts, but I use either a 35 volt or a 50 volt for a replacement to make them more resistant to voltage spikes.  The value is 4.7uF.

The other tantalum capacitors on the board should be fine since they are downstream from the 5 volt regulator and it’s very unlikely a voltage spike would get that far. They should last forever.

Also note that aluminum electrolytic capacitors have the minus “-” side identified on them and tantalum capacitors have the positive or “+” identified on them.  The circuit board has only “+” polarity identified for all capacitors regardless of type.  So double check the polarity of the capacitors before soldering them.