Hi

Does anyone know what is the typical current flowing through the (ignition sense) switched 12V line to the Rhapsody, Symphony, or Navi DX unit (or any other unit)?

I mentioned earlier that I have this annoying problem of CD changer "forgetting" track position, track number and CD number when the car is started and also when ignition key is quickly cycled. (The changer is actually the Solisto MP3 unit in my case).

Turned out to be 2 problems:

1. the constant 12V falls to a low value during starting and this resets the unit losing CD number, track number and track position. It needs diode isolation and battery backup (or a decent and always fully charged battery in the engine bay).

I solved this by putting in a Yuasa NP0.8-12 battery as backup and a Schottky diode to isolate the unit/battery from the car's installation when the voltage falls during startup.

2. The Rhapsody unit does not like the switched (ignition) 12V to be cycled quickly and also loses memory (usually just the track position, but not the track number / CD number) . To solve this problem, I want to use another low-dropout (Schottky) diode and a capacitor on the siwtched 12V line (yellow).

Now the value of the capacitor depends on how much current the unit takes via the switched 12V. E.g. I'd expect to put 10mF for every 10mA of current to get about 3.5s delay before the unit registers a drop in the switched voltage. After putting in the Yuasa I still have enough space left behind the radio to put another 30mF or so if needed

I cannot take the unit out until 2 weeks from now, but I'd rather prepare the filter wiring in the meantime.

So if you have your unit out, please measure the current and let me know. I am looking for typical value, so any Symphony, Rhapsody, or Navi DX will do.

Since I had this problem also in Octavia, with 2 different Blaupunkt units (CD only and CD/MP3), perhaps it'll help other people to know how to deal with it.

Edited 13 March, 200917 yr by dieselV6

Bump

And some additional info - the current I am after is on the "ignition sense" wire.

Come on, don't test my patience ( haven't got any ) asking me to wait for 2 weeks before I check it myself.

Bump

And some additional info - the current I am after is on the "ignition sense" wire.

Come on, don't test my patience ( haven't got any ) asking me to wait for 2 weeks before I check it myself.

Well, I can check the current on the wire but my car has an Alpine CDA-9853R, so I'm not sure if that'll help you or not...

Hi Bluefox,

Yes, any ignition sense value will help, even for a different stereo, even on an A2 TDI :P

Basically, I just want to know how much current the ignition sense line takes when the unit is on. It is probably a small current (single to tens of mA), with most of the power going through fused constant 12V pin (10A fuse on mine).

Given that I need an order of magnitude accuracy on this one (1mA, 10mA, 100mA? more?), it does not matter what head unit it is for.

I have the car abroad at the moment, and then I only have a 2-day window in the UK when I can pull the unit out and fix the problem, hence the request.

Still, after a few days of driving I am happy with the half of the fix I've done so far. The unit did not reset a single time so far, as long as I do not cycle the ignition on/off .

Perhaps a word of explanation why I want it fixed once and for all: with Solisto (or any other MP3 unit) you can have loads of music, but the head unit is limited to 6CDs of 99 tracks of 99:59 minutes each. Since I do indeed have 8GB of music, each track is an entire album. So when the track position reset, I had to scroll anywhere between 0 and 90min of music to get back to the same point (assuming I remembered the exact CD/track/time), which takes a few minutes itself. Hopefully, now you can see the annoyance factor.

Edited 13 March, 200917 yr by dieselV6

Yes, any ignition sense value will help, even for a different stereo, even on an A2 TDI :P

Bah.

I'm taking my stereo out of my SUPERB tomorrow so I'll measure the current from the SUPERB to the stereo.

Then I'll drive into you in my AUDI for being cheeky.