Attack from Mars Strobe

Attack From Mars features a high-intensity strobe located under the saucer. It fires during the saucer destruct sequence with occasional flashes. During strobe multiball, it strobes at about 7 flashes per second. It also strobes occasionally during attract mode.

The system has two boards. One generates the 200V needed to run the strobe. The other carries the strobe tube itself. The two are joined by a high-voltage cable.

The strobe controller uses 50VAC from the transformer for its power.

What Goes Wrong

The most common problem is that C1 fails. If this happens, the red LED will not glow (note: the glow is very dim on a working machine). C1 is run at about 160V, compared to a specification of 100V. Therefore, it fails within a few years of operation. The simplest fix is to move C2 to C1, and replace C2 with a new 100uF 100V non-polarized capacitor. The original C2 has plenty of life left in it.

Second most common problem is that the vibration causes the trigger transformer to break its fine leads. In this case, the LED will glow but the strobe wil not fire. Replace the trigger transformer. You can sometimes scrounge one from a cheap disposable camera.

Third, the trigger capacitors (orange blocks near teh triger transformer) sometimes crack internally. These need to be replaced.

Occasionally, previous repair attempts may have left flux on the board, which can cause all kinds of problems with this high-voltage board. It is really important to clean off flux residue.

Finally, the triac and SCR can fail with an overvoltage. Also, the reservoir capacitors can wear out. But the problems are mostly the first three.