AMG
Member
I just de-switchered my Defender, using a robotron/joust PS. PS was rebuilt with a Bob Roberts kit; and additionally the 18000uf cap, the 7905 regulator, and the 2n6057 darlington were replaced. Other than the 12v unreg being slightly low, the power looks good and the machine works. But now there's a hum through the speaker on powerup that lasts until the first sound is played (only a second). It didn't do this with the switcher. I swapped the sound board with one that was recently recapped, and it's the same. I removed the cable from the rom board to the sound board, and still no change. Is that hum normal on a Williams machine with a linear PS?


