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 Post subject: My old Sony, MDP-455, LD player w/ AC3 Demodulator mod
PostPosted: 21 Jun 2020, 02:38 
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I was going through my old archives and found pics of my first AC-3 Demodulator mod installed in a player.

This was a Sony, MDP-455 that I had back in 2002 and it was my 2nd LD player I ever owned (my first is still my Pioneer, CLD-3030). The mod was only partially successful as I'll explain later in the post. For now, let's check out some pics (my apologies in advanced regarding my camera focus; I was just getting into photography and I borrowed a friend's camera that wasn't all that great).

A view of the player in question.....

.... and a view of the underside (always liked Sony players in respect to seeing five isolating feet instead of the usual four on other brands)

Here is the image of the underside w/ the AC3-RF board to the right....

Regarding what I noted in this pic, the leads on the left power up and send the AC3-RF out signal to the AC3-RF Demodulator mounted on the top side. Also, per the instructions I received on this player about the lack of a mute control for the RF board, I still attempted to find one but failed in respect that anywhere I found a switching 5v point would adversely affect the player. Thus, as shown in the following pic, I ended up getting rid of the yellow wire and simply shorted the mute control per instruction.....

Moving on, here is a view of the AC3-RF Demodulator in the player...

.....and how the wires that were run through the plastic chassis....

..... and on the way to the newly installed RCA jack.....


So as I mentioned above, the mod wasn't totally successful and the key issue was the lack of a mute control on the RF board. The set-up did work and gave me awesome 5.1 audio but the big problem was that I would get an occasional loud squelch on my speakers just as playback was about to start. And of course, I found this very irritating as I did not want to be scared out my seat every time I started a movie (or started the next side change).

In any case, the player ended up having other issues as time went by and a shop I took it to stated that there was little they could do to remedy it (I think it was the spindle motor not getting up to speed or maybe the laser pick-up not reading the disc; can't remember). Regardless, since this was still the early 2000's, obtaining other players for dirt cheap made more sense instead of sinking more money into what was essentially an average player. The AC3 parts were removed before I tossed the player and they ended up in a Denon (RF board) and a ProScan (Demodulator board which was then removed again and currently not assigned to a new player yet).

All my subsequent AC3 Demodulator mods I have done since then have been perfect as all the other players have always had a good mute point for the RF board.

Hope everyone enjoyed seeing something different.
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