I have a Williams Jubilee and the transformer hum is too annoying to leave machine on. Hum varies with load and converting to LED helped. Completely unsoldering load did not completely stop humming. I figured it was bad transformer and bought exact Williams replacement on eBay. Replacement transformer has same hum. Tried mounting on rubber grommets but no help. I am assuming the transformers from this era were just poorly designed.

Has anyone come up with a work around? Looking for ideas. Could not find a new tech 6V/24V transformer. Could buy two separate transformers but I was thinking there is no reason not to use DC power supplies. The jet bumpers have rectified DC bridge but if supplied with DC it should still work. What current should be minimum required?

Please post your thoughts on this problem. I cannot live with the hum. Thanks.

I unsoldered the common output wire so nothing could be powered. Still had the hum. I always disconnect the coin lockout relay. The less humming the better.

Thanks everyone for the suggestions. The transformer lamination bolts were tight but I made extra snug. I hit transformer with rubber mallet at first and then tried hammer with no difference other than a few dents. I looked some more and found the "noise increasing under load" was actually the lock relay which was next to transformer. The lock relay seem to double the volume when activated. Even with lock relay off the hum is louder than my other machines. I am going to explore some other ideas I have and report back if a fix can be found. I am thinking using a DC supply would stop the lock relay from humming as well.