Aux-In Option via Tape-deck
 

I finally got around to adding an Aux input to my 1998 XK8 convertible today. I had seen the CD changer hack a while ago but I was hoping to avoid losing my CD input. After a bit of googling I came across this article which describes how to add an Aux-in via the tape unit on an X-Type.

How-To: DIY headunit hack for AUX-IN (on tape deck).

When I opened up my headunit, the tape deck and the 20 pin connector to the main board looked identical to the X-Type configuration although the daughter board and main board layout were different (Alpine chips instead of Sony).

https://cimg1.ibsrv.net/gimg/www.jag...3f24de1afa.jpg

Inside my 1998 XK8 headunit

My hunch was that the pin connections on the tape deck would be the same as the X-Type and sure enough they are. So the pins we need (counting from the left on the photo) are;

Ground -> pin 3
Line L -> pin 4
Line R -> pin 5


https://cimg2.ibsrv.net/gimg/www.jag...f50fe0368f.jpg

Close up of tape-deck daughter board

I traced the tracks from the relevant pins to the first joint and soldered on some shielded stereo pair cable. There's more space than trying to solder to the pins.


https://cimg7.ibsrv.net/gimg/www.jag...a4455affc1.jpg

Shielded cable soldered in

I had to drill a hole through the aluminium rear panel to lead out the cable and I finished it off with a 3.5 mm female jack socket.


https://cimg3.ibsrv.net/gimg/www.jag...a7fc6234ae.jpg

Hole in rear panel

You need to have a 'dummy' cassette in the drive to activate the tape channel, but once you plug in your iphone - bingo, crystal clear music. :icon_dance-twist:

Ok. This is really cool. I think I'm going to add this to my list of things to do :)

That's neat. I've been thinking about how to connect up the audio from my new Garmin sat nav and that might be a good solution.

For music, I spliced phono sockets in to the lead that connects the CD player to the amp and wired that up to a Motorola T605 so I get Bluetooth music or the CD automatically via the T605.

I am adding a bluetooth cassette adapter, was using the wired one, but it was noisy, so I opened it and took out all the gears, now it makes no noise, no issues with ejecting or switching sides, but dont like the wire from the deck.

I did try a Bluetooth cassette adaptor for a while but I wasn't happy with the sound. It lost a lot of high frequencies compared with the CD. It's an easy option though so it's ultimately down to how fussy you are about your audio quality.

That seems like the ideal solution for an AUX connection that I was looking for to make in my 2001 XJ8.
Assuming the unit is similar, without any research I opened it, only to find this:
https://cimg7.ibsrv.net/gimg/www.jag...aad34c9bfc.jpg
https://cimg1.ibsrv.net/gimg/www.jag...be34da1d8c.jpg


Although the tape unit looks the same, both the circuit board and the connector differ from the one found in XK.
My question is: has anyone tried to do the AUX-IN with this method in XJ (X308) and is it even possible ?

Greate post!


I was also bored with the tape deck and started with this mod , but ended up doing a Little more than that because I couldn't figure out which leads to use in the tapedeck. :)


If I had known how easy it was I probably would have stuck with this one. It would have been a bit cheaper.

I bought one of those plug in adapters to run my IPod thru and after some adjustment to balance and sound was quite acceptable, your fix is probably better but I don't think my old eyes are up to that fine solder repair

Actually, although the layout of the daughter board is different, it looks like it might be the same chipset and 20 pin connector. If it were me, I'd check to see if pin 3 was a ground connection, and if it was I'd take a punt on pins 4 & 5 being the same as the XK and X-type.

That is one very cool hack and certainly looks simpler than going the CD changer mod route, especially as regards cabling.

One question though - does anyone know, or have any thoughts about, whether this would work with the premium/Alpine system?

It is my understanding that our audio systems can be rather finicky about allowing "new" units into their exclusive, closed topology fiber optic loop. Or something to that effect, anyway.

Anyone?

This is a basic hack into line level circuitry rather than the proprietary network protocols so it should not effect the operation of the rest of the system, (it certainly hasn't on my installation). In theory it should also work on the premium Alpine system but I haven't tested it. It's just injecting another stereo signal source ahead of the extra amps/speakers so no reason why it wouldn't work assuming the pin outs on the daughter board are the same.

Question
 

Hi All

Would it not be simpler to hack into the cable that exits the head unit rather than soldering internally?

I don't think the tape signals are available on the external connections. You could probably hack into the CD analogue signals but then you would lose the CD functionality unless you built in some sort of switching arrangement.

OK I read all 211 posts on the thread referenced in the first post of this thread.

One issue mentioned is the ground loop issue when charging the iPod.

Bamforp, have you experance do this problem? I'm planning on doing this but want to be able to charge the iPod while in the car and there appears to be an issue with this due to ground loop.

I play my music via a bluetooth receiver plugged into the tapedeck aux-in hack. I did get a lot of digital interference when I tried to use a cheapo USB bluetooth receiver plugged into the cigar lighter so I ended up using a rechargeable unit like the one below which works fine.


I am not an electronics engineer, but I don't think the interference is a ground loop issue; it's just that the power supplies in the Jag are very noisy due to the various digital control networks. I am guessing the headunit and my iphone have some decent noise filtering on their power circuits so are not effected by the interference but the cheapo USB receiver has no such filtering. It would be great to get an opinion from an electronics engineer on this if there is one out there!

From memory, if I plug my iphone directly into the aux-in I don't get any interference even with the iphone on charge but I will double check tonight.

Regards

Peter

OK, I checked out my set up and my memory failed me! I get the interference when the iPhone is on charge and plugged into the aux-in. With the iPhone still on charge I unplugged the aux-in and plugged in some headphones and the interference disappeared. It looks like there is some sort of ground loop or similar going on so it would be great to hear from an electronics expert on a possible explanation. I will also read the full thread on the original post for any clues.

Having said all that, I am still very happy with my setup so it won't be a big problem if there's no easy fix.

Peter

An inexpensive ground loop isolator will solve most ground loop problems without a lot of guesswork:

I bought this ground loop isolator from eBay and tried it out last night. I can confirm it removes the high pitch interference but it also kills all the top end of the music. I assume it's just some sort of low pass filter.

Anyway, my advice would be don't go for this hack if you plan to charge your playback device at the same time as playing music.

I'm curious if the CD hack has the same issues.

A proper one uses a transformer, and they may vary in quality. You may have better luck with a brand name unit instead of a generic Chinese one.

OK - I'll take the one I bought apart and have a look inside.

Loving my RealGauge by the way.