Did some radio hacking, wrong.

GTE

Hello all!

I decided to get my iPod fitted into my 2000 Golf with a base spec "Beta" radio.

I wanted something rough and ready so what I did was solder the left and right channels from a cable going from a headphone jack directly into the radio amps 1 and 2 inputs.

So whatever I am hearing on the radio/tape/CD "meets" the iPod signal just before the amplifier and sent off to the speakers.

It works very well for the most part. I can either press play on a tape for silence and play the ipod or I can just turn the volume to the first click after 0 and play.

The iPods volume control dictates the overall volume of the ipod. The headunits volume knob has no influence on the ipod playback level unless its set to 0 - mute.

http://www.alldatasheet.com/datasheet-pdf/pdf/25152/STMICROELECTRONICS/TDA7376B.html

This is the amp. I soldered the left and right audio cables (4 in total) to In1+, In1-, In2+ and In2-.

I was very happy with myself until:

Problem 1 - When the iPod is on I can not hear the radio unless I crank the volume knob. When I say "on" that is either the menu screen or the 10 or so seconds before it goes to sleep after pressing the sleep button or holding down the on/off button.

Problem 1a - When the headphone jack is plugged into the off ipod I lose a considerable amount of low end. Unplugging the iPod fixes this.

Problem 2 - Once I plug the ipod into the in car charger all signal disappears and I am left with a consistent loud popping from one speaker. Most likely two but I really hear it much more in the right speaker.


Problems 1 and 1a can be fixed by putting a double pole double throw switch across the cable coming out of the iPod, I was expecting something to happen which would need this. Though, even having expected summet along the lines of problem 1a I cant understand problem 1. I cant figure out why I lose the radio/tape sound if the ipod is playing unless that is causing a detectable overload which shuts off the amp? But anyway, I need that DPDT.

Problem 2 is more serious and confusing.



That is the radio. Blaupunkt.

I would have preferred to intercept the signal from the tape deck which meant I could select between tape(now ipod) and radio. I managed to find one place to do it, just after the tape deck itself and it was distorting like a mofo. There must be a preamp after that point and before it hits the main amp. I wanted to find the point after the preamp and before the main amp but I am clueless about where it is. Although I would like to be able to use the switch on the HU to select between Tape(ipod) and radio using the DPDT is fine. The charging issue is a big problem.

I just had a thought about my problem when I plug the ipod in for charge.
Should the power for the ipod be coming from the same power cables that are used for the radio?
My Beta radio had a CD player above it and although I dont use that I could use the cables that come out of the radio to the CD player to supply the ipod with power.

Thanks all,
bbk

GTE

http://codedradio.info/manuals/blaupunkt/vw-beta.pdf

This lists the tape preamp but I am not winning at finding the point where I should solder into, and even at that I dunno if I could find it on the actual radio.

Tomk1

Did something similar a while back with a tape deck, just disconnected the wires to the tape pickup and wired in an audio jack, also disconnected the motor, worked but had to keep the mp3 at low volume, as the normal tape pick up single is low.

Why didn't you use the CD line in wires with a tv-s-cable selector.

Aside a while ago I saw in the Maplins catolog an ipod radio head without a CD player, you could open the front and put the ipod inside where it plugged in, then close the front. Looked great and was cheap about €65 (and you know their mark up prices), but it was dropped from the catalog.

GTE

The tape preamp is so small that I cant do anything with it.

The reason I wouldnt use the CD player is because I have a storage cubby taking its place now, also when I did that before, about 2 years ago, I think the audio quality wasnt great.

I will just settle with the DPDT on that front.

I am still confused over the popping noises though.

GTE

Well hello again.

I gave up with whatever the hell it was I was trying to do and just intercepted the CD players audio lines and put the ipod into that.

Now, it worked great UNTIL!!! Yes, until I plugged in the charger. Once I do I get an alternator whine.

No whine under radio so the problem can not be what ever I was doing with the amp, at least in my mind.

Any info would be great.

At the moment the left and right audio outs of the CD player (separate unit) are disconnected and so is the common ground which I assumed was for the returns from the L and R audio lines.

Now, the L and R and common wires are which are usually connected between the CD and headunit are now connected between iPod and head unit. Works great until I plug in a cigarette lighter charger.

Minds melted.