mutant_matt

I guess this is the most likely forum so here goes:

I've recently installed a set of Defi gauges and an Inlet Temp gauge. What I have noticed is that the switched live power supplies that I have so far found (several of them) seem to give you 12V+ when the ignition is on (as expected), but when you switch it off, this supply then slowly decreases and after about 15-20mins, is back to 0V. (it's almost as though the switched live feeds are coming via some sort of capacitor...??? )

Is this normal on a car (Scoob in particular) or are there some "proper" switched live feeds available? (by proper I mean, 12V when on, 0V when off)

Also, does anyone have any opinions on whether or not this kind of slowly diminishing power supply may cause any damage to the equipment in question which (I presume is expecting either 12V or 0V)???

Any help most appreciated,

Matt

David_Wallis

What are you testing this with??

Are you using a multimeter??

The chances are the voltage is staying there because of many reasons but very likely to be a capacitor in something...

Assuming the supply can take the added current, get a small 12v bulb... interior light or something and try this accross along with the multimeter... will probably make the voltage drop straight away as there will be insufficient current available from a small cap.

there is definitely a 12+ switched feed at the back of the radio...

let me know if you need to know which wire...

If you use a relay dont forget to put a diode on it..

David

mutant_matt

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:<HR>Originally posted by David_Wallis:
<B>What are you testing this with??
Are you using a multimeter??[/quote]

Yes - a fairly good one (I think )

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:<HR><B>Assuming the supply can take the added current, get a small 12v bulb... interior light or something and try this accross along with the multimeter... will probably make the voltage drop straight away as there will be insufficient current available from a small cap.[/quote]

Even if this makes the voltage drop straight away, it doesn't really solve the "problem" (if indeed it is a problem)....

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:<HR><B>there is definitely a 12+ switched feed at the back of the radio... [/quote]

I know, I'm using it to power the switched live input to my Defi gauges and this suffers this problem

Have you tried measuring this particular feed with a multimeter? Turn the ignition on and you should see it go straight to 12V, turn it off and it will fairly quickly drop to about 6-8V but then it slows down and takes about a further 15mins to drop to 0V.

Strange huh?

Thanks for the reply BTW...

Matt

Chris Clayton

Matt,

I've just installed my Defi gauges and took
the permanent +12v from the back of my radio
and the ignition switched supply from the
same loom.
Mine works no problem - goes instantly from
+12V to 0 on switch off, so yours sounds
mighty strange.

Just a thought - you havnt got a Interior light stay on circuit added have you that
keeps the interior light on for a few seconds
after you close the door - sounds just like
something like this might be discharging
into the switched feeds.

Chris C.

mutant_matt

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:<HR>Originally posted by Chris Clayton:
<B>Just a thought - you havnt got a Interior light stay on circuit added have you that
keeps the interior light on for a few seconds
after you close the door - sounds just like
something like this might be discharging
into the switched feeds.[/quote]

No I haven't - and I've checked it out at the fusebox as well (and of course it's happening there also).....

?????

Matt

David_Wallis

Wierd.... I will check this on mine when I get home...

Seems very wierd though...

Let me know if you work out what it is!

David

chiark

This is a known problem. It's the reason that some Panasonic and sony head units stay on for 20 or so seconds after turning off the ignition...

Best guess is that it's something to do with the conversion harness that's being used in the factory wiring.

I took my feed from the back of the fusebox for dials and have no problems.

A way to solve it, believe it or not, is to turn the wipers on and off after you've turned the ignition off. This drains the power out of the system and drops voltage to 0, which makes me think that there's a cap somewhere in there...

Do let us know how you get on, it would be good to get to the bottom of this one...

Nick.

mutant_matt

Thanks for that Chiark - glad I'm not the only one that has the "problem". If they are all like that then I don't think I'll worry about it

BTW - the Defi stuff I sent you, any good? Need anything else? (I haven't heard from you in a few weeks....)

Matt

PGMabley

I have this problem too MY99.

The wiper thing works well, but I have noticed that if you open the door (and the interior light comes on) after the radio has powered down from switching the wipers, it comes back on again (Blaupunkt and Philips radio have both been tried)!

This never happened on my old MY98 and strikes me as the wiring being 'Mickey Mouse' in this car - it is a little frustrating.

I am thinking of getting DEFI gauges - will it cause problems or is there a way around the problem?

Paul

mutant_matt

It's not really a problem - it's more a "feature" of the car it seems.

The Jap models don't seem to suffer but I guess they use a different loom...

However, I've only checked with one Jap car onwner, any one else???



Matt

mutant_matt

Anyone else????

Matt

chiark

Matt, argh, the defi stuff! Sorry, I've been up to my armpits in work recently if you hadn't guessed. I'll update it tomorrow (I'm on a train for 4 hours)!

Thanks!

dowser

He-he - explains why my Panasonics stays on for 20 secs or so after ignition off (except sometimes when it's raining) then

Thanks
Richard
my00