Defender hum on startup

[AMG]

Ken, are you talking about a hum just on start, or one that's there during attract/play?

There are definitely some that are worse than others, though. I had a Joust that had a noticible hum. I tried everything suggested here, monitor off, fluorescent unplugged. verified grounds (the sound & PS boards were mounted on the same steel plate) and it still hummed. Swapped PS boards. No difference. Tried a differerent speaker, no hum when it was plugged in outside the box, hummed when swapped in for old speaker. Finally rebuild the sound card, replaced every capacitor on it. Still hummed. Rebuild an old fried sound card. No hum.

Put the card that hummed in a different cabinet (Robotron) and it worked fine. Sometimes they just don't know the words.

ken

 

[YellowDog]

Ken, are you talking about a hum just on start, or one that's there during attract/play?

It was very noticible on startup but faded during the normal gameplay. When there was a break between games during the attract mode it was noticible, just not as noticible as during startup. I found it detracted so I kept trying to fix it. But I am rather picky about my Williams games

ken

 

[AMG]

Once fixed, was the cold-start hum gone too?

It was very noticible on startup but faded during the normal gameplay. When there was a break between games during the attract mode it was noticible, just not as noticible as during startup. I found it detracted so I kept trying to fix it. But I am rather picky about my Williams games

ken

 

[YellowDog]

Once fixed, was the cold-start hum gone too?

Not completely. There is always some startup noise on Williams games. The main thing is that the hum is gone when the game plays.

ken