New car radio -> Ignition overload lock?

Hello,

I want to give my girlfriend a car stereo for Christmas. I've decided to go with a Sony. When I was reading reviews on ciao.com, I came across the following:

Here's a tip for all Volkswagen owners who purchased their car after 1999. You'll need an additional adapter to prevent overloading the ignition switch. I also bought this adapter at the Tevi store for 32.99 euros. If you don't use this adapter, the radio will work fine, but over time, the electronics in the ignition switch will fail. This applies to all radios intended for installation, with the exception of VW-branded radios.


Is there any truth to that? What is the adapter actually called? Where can I find something like that?

Okay, the car is a new Polo (the one with four headlights) and it has a 1.2 three-cylinder engine .

Sure, no problem.
David.

Hi,

Okay, I would save the 32 euros. Buy a standard relay and integrate it into the wiring for the radio in such a way that it only connects the constant positive voltage to the positive wire when the ignition is on. Then you only connect the relay to the switch, and nothing else, and the radio will be powered directly from the battery.

Best regards,

Jan.

Hi Jan,

Thank you for the tip.
I'm not entirely convinced that something like that is even necessary. Usually, a radio draws its main power supply from the normal positive terminal of the battery. Doesn't a relay already exist within the radio itself? The ignition plus is only for the radio's internal memory and, possibly, for any relay circuit that might be present, right?

I found something else; perhaps it's just referring to this adapter.

When installing a non-VW radio, it's important to note that VW uses a phantom power supply for the antenna, and the ISO connector pin configuration needs to be adjusted. The phantom power supply provides power to the antenna via the antenna cable. Without this phantom power supply, only strong radio signals can be received. If the aftermarket radio does not support phantom power, an adapter can be installed for approximately 10-20 €. Adapters are available, for example, from VW (part number 1H0 051 551).

Whether a car radio draws its power from a constant positive terminal or from the ignition positive terminal depends on the radio manufacturer and their design philosophy.
The ignition power is only for the radio's internal memory
No, not right now. The memory needs a constant power supply, so it's connected to the constant positive terminal, not the ignition positive terminal.

It's sometimes possible to tell where a radio draws most of its power by looking at the cable cross-sections. Very old radios only had a simple wire connected as a constant positive voltage, which only powered the memory, while everything else was powered by the ignition voltage.

Radios that can be turned on even without the ignition (e.g., Blaupunkt) naturally draw power from the 'main power' line via the constant positive terminal and only receive the power-on pulse from the ignition. You can safely connect this to newer VW vehicles.

Otherwise, I would follow Jan6k's tip, which is reliable and costs less than five euros. The phantom power supply, which may be necessary for the antenna, can also be easily implemented yourself using relays.

Regards,
Private.

Hello DocSnydor,

Quote:

I found something else, maybe it's just this adapter that's being referred to: "Quote:" When installing a non-VW radio, it's important to note that VW uses a phantom power supply for the antenna, and the ISO connector pin configuration needs to be adjusted. The phantom power supply provides power to the antenna via the antenna cable. Without this phantom power supply, only strong radio signals can be received. If the aftermarket radio does not support phantom power, an adapter can be installed for approximately 10-20 €. Adapters are available, for example, from VW (part number 1H0 051 551).

I have a Kenwood radio, and I can confirm this issue. Once I drive out of the DD area, the radio can no longer find any stations. This adapter is also mentioned in the radio's manual (specifically for VW vehicles). I haven't bought it yet, but it's recommended, especially since the reception is really bad in the city.

Best regards,
Albrecht.

@DocSnydor

I've never heard of a ignition switch overload. Nowadays, the power comes from the constant positive wire, and the ignition is only there to turn on the radio. Otherwise, you have to be careful about the wiring (you can easily damage the radio if you get it wrong). Phantom power for the antenna is not strictly necessary (it's not needed for the 35i, at least), but it's a good idea because it can improve reception (since it's a booster antenna).

Best regards, WarLord.

Hi,

I would be cautious about that, because firstly, it's not guaranteed that every radio actually behaves in a way that draws power directly from the main power line, and secondly, the "switched +" connection on a VW radio is not actually the ignition power supply!

When you turn off the ignition, the ignition plus circuit also turns off, but the radio remains on. It only becomes clear when you turn the key, and that's because the "switched +" line is supplied by that other contact (whatever it's called... the one that activates when you turn the ignition and deactivates when you remove the key).

If you don't believe it... turn off the radio, grab a multimeter, and measure it yourself. "It's the same with my Ibiza, and it was the same with my Polo from 1997."

I've also read elsewhere that this contact should only be lightly loaded, as it's really only there to tell the radio that the ignition is on. You shouldn't connect anything to it, not even something as simple as a ham radio, which draws far less power than a regular radio.

Other cars are different, and the ignition plus line is load-bearing, so I immediately believe that there are radios that want to draw more than just a few milliamps from this line.

"Act as a relay, but only if there's an explicit warning about it from Sony." Or, you can connect it directly to the ignition power line instead of this one, which means it will turn off as soon as you turn off the ignition, rather than only when you use the key.

Best regards,

Jan.

Hi,

According to VW, the S-contact (which is what @Jan calls it) on the ignition switch should only be loaded with 300mA. Using a relay to switch it is the most sensible approach... but be careful!! Don't forget the freewheeling diode! Otherwise, the S-contact will eventually fail due to the voltage spikes from the relay. Many ignition switch failures are due to wear and tear on the S-contact.

Okay, and one more thing: The new connections from VW have a "SAFE" marking for the constant power supply on the A5, while the other radios have the antenna power output on that connection. If you don't disconnect the cable from the vehicle's side, your new radio will immediately burn out.

I would connect the active adapter to the antenna, as the reception with the roof antennas is practically nonexistent.

Wow, this is all so complicated. Buy new cars...
Unfortunately, I don't really know much about electronics. I can still manage to deal with a relay, but what exactly *is* a flyback diode??? And how do I connect it? Is there any website where I can find this information?
If I understand correctly, I theoretically need 2 adapters: one for the S-contact and one for the phantom power!
Thank you very much for your answers...

I would say that this is just scaremongering. Those at Sony surely know what they are doing, and I think it's rather unlikely that you would draw five or more amps from the ignition switch these days. I've also never heard of a car where the ignition switch failed for such a reason.

@Bertil

I've figured out the antenna situation at my place because I've been having major issues with ground loops (no, not a simple ground loop) and the signal from the transmitter is only slightly weaker than with phantom power. However, it's possible that your Golf behaves differently.

Best regards, WarLord.

Hi DocSnyder,

You simply connect a flyback diode in parallel with the relay coil, but in the reverse direction, otherwise it would cause a short circuit.

If the S-contact is now switched off, the collapse of the magnetic field induces a counter-voltage that could damage the contacts of the switch (e.g., arcing). The diode shorts out this voltage, and that's all there is to it.

Best regards,

Jan.

@docsnyder

Take a look at this; here you'll find the pinout http://www.margh.de/.
Okay, but if the Polo is from the Netherlands, forget the wiring diagram from the link I sent. My Dutch-spec Highline Golf came without a radio, but it did have the original 8 VW speakers, all connected to a proper ISO connector with the correct pin assignments. It took a lot of effort to install a genuine German navigation system.

But the thing about the ignition is also new to me, thanks for the tip. I also wanted to get a new radio for my girlfriend (!).
I wouldn't want to give away the VW Alpha... no, I don't think so. It's the biggest insult; for this outrageous price, you can get top-quality products elsewhere!

WarLord wrote:

... @Bertil I've figured out the antenna situation at my place because I've been having major issues with ground loops (no, not a simple ground loop) and the signal from the transmitter is only slightly weaker than with phantom power. However, it's possible that your Golf behaves differently.

So, the attenuation provided by the original VAG antenna is measured to be 20-40 dB (6 dB corresponds to half the power - logarithmic scale!).
"Because I deal with numerous requests regarding phantom power for various vehicles on a daily basis, I can only recommend installing the adapter. Especially those who live in sparsely populated areas, such as the highlands, should ensure they have a properly functioning antenna. In my daily commute to work (45 km of country road), my radio switches between 12 different stations. This involves using 4 different frequencies." If the antenna weakens, then you'll have fun.
Whenever reception tests are scheduled, I am allowed to take a test drive .

P.S.: My Golf doesn't have the original antenna anymore.

You simply connect a flyback diode in parallel with the relay's coil, but in the reverse direction, otherwise it would cause a short circuit.

If the S-contact is now switched off, the collapse of the magnetic field induces a counter-voltage that could damage the contacts of the switch (e.g., arcing). The diode shorts out this voltage, and that's all there is to it.


Thanks, Jan, that was a great explanation. I understood it right away the first time I read it ...

@matthiasTDI96

Thank you for the link. Very helpful indeed...
'Our friends will be so happy when they don't have to deal with that Alpha guy anymore. The only good thing about the radio is the lighting. I still think the red and blue looks great...' Ours will probably go for around €1.50 on eBay.

@warlord
You don't need any phantom power for our Passats. I can't really complain about the radio reception. I have a cheap '16V Style' antenna on the roof, which I've even shortened by half. Still, I get all the stations clearly and without any noise. It might also be because I have a Blaupunkt radio installed.
By the way, about that whistling sound. I used to have that too. I had a Pioneer radio with a CD changer installed. It made a 'nice' speed-dependent whistling noise. After the radio replacement, it went away, even though I didn't change anything else .

@Bertil

Well, you know what your radio does. Mine usually plays from CDs. *g*

@DocSnydor

I have the original VW antenna mounted on the roof. I believe it requires a phantom power supply. My JVC radio (KS-LH4R) is new and I really don't want to replace it because it's great. If the radio is powered from the Punto's system, there's no humming. If the amplifier is powered from the CD player, there's also no humming. But when they're both connected, that annoying humming appears. That's why I'm planning to remove my amplifier soon (I don't even have a subwoofer installed, so it's not like I'm missing anything).

Best regards, WarLord.

WarLord wrote:

... I've also never heard of a car where the ignition switch failed for such a reason.

How many "non-defective" ignition switches do you need? I have 3 lying around on my desk alone. The problem is that VW uses the constant power and ignition power connections in the wrong way, and many people simply plug the connector in (it fits, after all). After a week, the unpleasant surprise arrives... because the S-connector then had to supply power to the amplifier stage (easily 20A for high-power devices).