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2005 XT Manual
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15 Posts
Discussion Starter #1
Hi, can someone help please. It’s weird question!
I use an old pullout type kenwood radio unit in my kitchen powered by a 12v transformer which is isolated every time I turn the radio off. I don’t want the transformer running 24/7 for obvious reasons.
I want to fit a Kenwood KDC-BT720DAB CD Receiver with Built-in Bluetooth & DAB+ Radio to improve things but this unit comes with a constant and switched power input, I will only have switched 12v power.
Before I buy it, can any one advise if this 100% power isolation will reset everything ever time it’s turned back on and be impractical to use? Ie stations, phone Bluetooth, audio settings etc...
I am hoping the constant 12v is just for the ignition off, timed continued play, but not confident enough to take a flier.
Any help welcome.
Thanks.
 

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Administrator
2007 Forester Sports XT 4EAT
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38,701 Posts
@Old Shoe I have a spare head unit installed in the master bedroom to provide music in the bedroom (front speakers) & in the master bathroom (rear speakers). :biggrin:

The constant power is used for the clock & presets. If you don't have constant 12V, the head unit will lose the clock setting & any presets... like radio channels & audio setting that you have saved, every time you switch it off.

No worries about the constant 12V using much power. Think of it as the CMOS battery in a computer that saves the settings, so they don't have to be reset every time the computer is turned off & back on.

Bottom line, the 12V power supply has to be on all the time to provide the constant, unswitched 12V power.

I'm using a 12V, 10A switching power supply, which is very efficient. It doesn't even get warm to the touch. I got for cheap on eBay, shipped from China, so it took a VERY long to arrive! :icon_eek:

I also got that LED voltmeter on eBay, installed that for fun. It shows 12.5V on the picture, but it's set to 12.9V now. :wink:

Bobby...



['07 FSXT MODding Journal] ['03 X MODding Journal]
 

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Registered
2005 XT Manual
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15 Posts
Discussion Starter #3
Thanks for taking the time to respond Bobby, thought that might be the answer. Pic of the power supply is useful, never too sure about the quality of some of the things available on the net so it’s good to know yours is ok.
An audible buzz was a worry with a switched supply, but I’m going to to get the new unit now, try it on my on/off situation knowing I’m safe with the constant supply via your type of power source.
Haven’t seen my old transformer since it was installed, it’s burried under kitchen units, but I remember it was some Russian military sourced thing, probably very good, just not happy leaving it on constantly.
Nice to know also... with all the modern tech these days....., in I’m not the only one with this setup!
Cheers and thanks again!
Jon.
 

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Administrator
2007 Forester Sports XT 4EAT
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38,701 Posts
@Old Shoe those cheap "wall wart" type switching power supplies can be problematic! I've had VERY bad luck with those on my Jensen portable radio & even my digital answering machine! There was an audible buzzing sound! :mad:

This is an on going project to move to efficient switching power supplies, so I still have the "working" factory/OEM power supply. That simplified the "buzzing" trouble shooting.

• Cheap "wall wart" switching power supply = buzzing.
• Factory/OEM, original power supply = NO buzzing!

The higher output commercial switching power supplies have better noise suppression. In addition, a vehicle head unit will have built in noise suppression. :wink:

Good luck with your project!

Bobby...

['07 FSXT MODding Journal] ['03 X MODding Journal]
 
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