Hello all,
After years of searching for a US spec
Denon LA-3500 with AC3 I finally gave up and purchased a Japanese
Denon LA-3500G with plans of modifying it with a homemade AC3 board. I decided to go with the board designed by ldfan. While procrastinating on the project I found a US spec LA-3500 with AC3. This made finding all of the pickup points much easier. I also compared all of the components in the power supply and confirmed they are exactly the same. This leads me to believe that it's safe to run the J spec 100VAC player on 120VAC. The bridge rectifiers are rated for 200V. The Denon AC3 board appears to be an attempt to keep the LA-3500 up to date. I have documented to the wire colors and what they are for. I was able to duplicate this on my 3500G with a multicolored ribbon cable. There are 5 wires on the factory AC3 board.
Brown- Ground (ground plane of top circuit board)
Red- RF pickup point (base of TR203 transistor)
Orange- +5VDC (CN13A pin 2)
Yellow- -5VDC (CN13A pin 6)
Green- Mute active high (CN13A pin 11)
CN13A connector pinout is located on Pg. 83 of the service manual.