Silvercoin,
My best guess is that big ol' 30,000uF Capacitor on the back box not doing it's job.
Put a load on the lights, the AC is getting through to the audio system. (it is not filtering too well)
It could also be the bridge connected to it as well.
Bud

Silvercoin,
JokerZ manual page 40, lower right back box.
That supply feeds the lamps via CPU board.
Bud

Backbox_(resized).JPG

Backbox_JokerZ_(resized).JPG

27,000uF would work fine.
https://www.greatplainselectronics.com/products.asp?cat=67

Bud

Riverboat Gambler SYS11C for sale.
Nice SYS11 for anyone's collection.

Machine - For Sale

Riverboat Gambler (Williams, 1990) Archived

Fully restored (full original status) - “For sale is a Riverboat Gambler The Good: The colors and art on this machine are outstanding! NOS playfield installed - HSA clear coated Cabinet was gutted, cleaned and painted i...”

2017-09-04

Westerville, OH

Budwin

2,900 (OBO)

Archived after: 49 days

Viewed: 785 times

Status: Not sold

Well, I just pulled mylar from my Dr Dude and there were a couple of places where art was pulled up on inserts.
It is just the way it goes when there is an area that got heated by the bulbs to deteriorate the art under the mylar.
The deteriorated (heat damaged) art tends to lift and stick to the mylar.
Good Luck.