# Adding an Optical Out to a Headunit, Identify a Chip



## Sulley

I've been fighting with a noisy pioneer head unit for quite some time now and in my searching for solutions I've come across how a few people had added an Optical output to there head units. Me being me I desided I must try it out, but first on the factory head unit so in the odd chance I destroy it, well no big loss.

I've ran in to a snag though, OEM head units seam to be a little bit more secretive on there parts compared to the after market ones, Anyway I believe I have located the correct chip but I can't seam to get a Data sheet with a pin-out for it.

Can anyone help me find some Info on this chip? or know where I can go to find it? a Google search and alldatasheet.com is turning up blanks.

Please help, I'd love to have a digital out

Heres whats printed on the Chip in question ... 

Alpine 
25729 
AM JAPAN 
318U4D60

And some pictures... Cause well everyone like pictures.










I'm lead to believe that the alpine chip is the correct one because if you look to the left theres connector where its already split L-ch & R-ch. The Panasonic and the BA59... one are for operating the transport itself.


----------



## t3sn4f2

Just so you know, head unit digital outputs are fixed level like home CD sources and need to have master volume control done from the device the digital out is fed to. You also won't get any other source out the digital interface other then the transport.


----------



## Sulley

Yup, just cd out. It will be ran in to a miniDSP/digi combo for now with a external pot for volume control, eventually I plan to get a bitone. 

I assume if the transport can read CD-R, I should have any problems with burnt off disks?


----------



## t3sn4f2

Should work the same, as long as like you say the disc loads and reads fine.


----------



## Sulley

Well it did work before I took it apart... When it goes back together is a different story lol

If I got in contact with alpine directly would they give out this kind of information? This chip is probley not made by alpine directly is it?


----------



## t3sn4f2

stockley.rod said:


> Well it did work before I took it apart... When it goes back together is a different story lol
> 
> If I got in contact with alpine directly would they give out this kind of information? This chip is probley not made by alpine directly is it?


Seriously doubt it is. Although it could be made just for them by the chip maker. Which would make getting the pin out pretty impossible unless you can get a service manual for that unit.


----------



## envisionelec

stockley.rod said:


> I've been fighting with a noisy pioneer head unit for quite some time now and in my searching for solutions I've come across how a few people had added an Optical output to there head units. Me being me I desided I must try it out, but first on the factory head unit so in the odd chance I destroy it, well no big loss.
> 
> I've ran in to a snag though, OEM head units seam to be a little bit more secretive on there parts compared to the after market ones, Anyway I believe I have located the correct chip but I can't seam to get a Data sheet with a pin-out for it.
> 
> Can anyone help me find some Info on this chip? or know where I can go to find it? a Google search and alldatasheet.com is turning up blanks.
> 
> Please help, I'd love to have a digital out
> 
> Heres whats printed on the Chip in question ...
> 
> Alpine
> 25729
> AM JAPAN
> 318U4D60
> 
> And some pictures... Cause well everyone like pictures.
> 
> 
> 
> I'm lead to believe that the alpine chip is the correct one because if you look to the left theres connector where its already split L-ch & R-ch. The Panasonic and the BA59... one are for operating the transport itself.


You need to find the DAC. From there you will have recognizable SPDIF and CLK data feeding it. Chances are, it's all in the Alpine ASIC. It's a custom masked unit made for Alpine. If that's the case, then the data isn't brought outside of the chip and you're stuck unless you're in the mood for building a custom transport.

All you need is an oscilloscope and a test CD. Start probin'!


----------



## kakashi

Hello, sorry for digging this thread, but I have almost(if not) the same CD unit(for Jaguar OEM radio). Can you feed me with info, where exactly are splitted L-ch and R-ch? I want to make an Aux-in line and I don't know where should I connect cables... Sorry for my english


----------

