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 Post subject: [LA-3500G] AC3 mod
PostPosted: 05 Sep 2022, 19:00 
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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.
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 Post subject: Re: Denon LA-3500G AC3 mod
PostPosted: 05 Sep 2022, 19:34 
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I had no idea that the LA-3500 had versions without the AC3-RF output. I checked the service manuals available on-line and none of them mention the AC3 circuit so it had to be a last minute add on.

Could you post pics of the AC3 board in your 3500? Curious to see if it looks anything like the one that was used in the McIntosh, MLD-7020.
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 Post subject: Re: Denon LA-3500G AC3 mod
PostPosted: 05 Sep 2022, 20:36 
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Here is a pic of the factory board.


Attachments:
My project.jpg
My project.jpg [ 43.98 KiB | Viewed 631 times ]
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 Post subject: Re: Denon LA-3500G AC3 mod
PostPosted: 05 Sep 2022, 20:43 
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Attachment:
File comment: A side by side pic of both players.
My project (2).jpg
My project (2).jpg [ 53.16 KiB | Viewed 631 times ]


A pic of both players side by side.
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 Post subject: Re: [LA-3500G] AC3 mod
PostPosted: 06 Sep 2022, 04:33 
Hardcore fan
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Definitely that AC3 board looks different from the McIntosh version. I guess every company customized their own design for their aftermarket AC3 mods. Very cool :thumbup:
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