dc regulated power supply problem

Submitted: Thursday, Mar 10, 2011 at 20:49

ThreadID: 84917 Views:2837 Replies:4 FollowUps:9

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Grass Parrot

Way out of my depth here. Going away tomorrow afternoon. Have had power to the van all day packing ready to go away. Was playing a CD in the van and it cut out after 3 songs and the lights starting flickering and surging. Checked all the power and have worked out the van interior lights and cd player are ruuning off a dc regulated power supply. It plugs into a 240v power point and has 12v wiring coming out of it. It has wording on it saying Input 220-240v and Output 13.8v 20 amp.

Is this device broken as when I try and play the radio/cd player the lights go really dim and there does not seem enough power to run the radio/cd player. Fridge and microwave are working fine (I think they are running off the direct 240v power source).

Any help appreciated.

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Reply By: Ianw - Thursday, Mar 10, 2011 at 21:07

Reply By: MattR - Thursday, Mar 10, 2011 at 21:13

Thursday, Mar 10, 2011 at 21:13

It could be the problem.

I'm assuming that when you unplug the power supply from 240 V, the radio/CD and lights quit working but everything else keeps going, and this is how you know that the power supply is powering those items.

If you can follow the 12 V wiring coming out of the power supply, you might see if there are any places where there seems to be a bad splice, cut wire, etc. Maybe a little solder or electrical tape is all you need. If there is a terminal strip or binding posts for the 12 V output of the power supply, make sure the screws / posts are tight - stuff like that.

There may be a small 12 V fuse panel or the radio may have an in-line fuse. Pull out the fuse for the radio and see if the lights work OK... maybe the radio has a problem and is loading down the power supply.

You might also unplug the power supply from the 240 V power point and plug something like a table lamp (from the house) into the same power point and make sure the lamp works OK - there might be a problem with the 240 V wiring.

If you have a spare 12 V battery with a reasonable capacity - a car or motorcycle battery, a garden tractor battery, even a small sealed battery from a computer UPS - you could temporarily substitute it for the power supply and see if that makes the lights and radio/CD work. Make really sure you know which wire in the van is negative and which is positive. Unhook both wires from the power supply and connect the negative one straight to the negative terminal of the battery. Connect the positive wire to one end of a 20 amp automotive fuse (either plastic blade type or glass tube type) and the other end of the fuse to the positive terminal of the battery. Try the lights and radio again and if they work fine, the power supply is likely the problem. (Don't leave out the fuse! If the problem is in the 12 V wiring in the van, the fuse will blow, instead of letting the battery burn up the wires.)

You might not want to take the battery with you unless you figure out a way to bolt it down, vent it to the outside world, and recharge it, but at least it can help tell you if the power supply is bad.

I hope this helps!

MattR

AnswerID: 447876

Follow Up By: Grass Parrot - Thursday, Mar 10, 2011 at 21:20

Thursday, Mar 10, 2011 at 21:20

Thanks Matt. Have done some of those things but not all. Will give them all a go and see how I go. Your first paragraph is correct. Have had the van for two years and this is the first time it has done this. The power supply box looks fairly new.

FollowupID: 720226

Reply By: Roughasguts - Thursday, Mar 10, 2011 at 21:20

Thursday, Mar 10, 2011 at 21:20

Then the house battery must be dead.

The battery alone should run the lights , and CD! and maybe you might get a trickle from the charger to keep the Power up according to demand.

Sure sounds like a battery problem or loose wire from your battery.

Cheers

AnswerID: 447877

Follow Up By: farouk - Thursday, Mar 10, 2011 at 21:35

Thursday, Mar 10, 2011 at 21:35

To my knowledge you do not necessarily need a battery to be installed as the transformer is wired into the 12v circuit and even if the battery was suspect if the transformer was working there would still be lights and CD player, so I would suggest a problem with transformer.
Suggest you disconnect transformer and wire a battery charger into circuit and see what the result is.
Colin

FollowupID: 720229

Follow Up By: Mike DiD - Thursday, Mar 10, 2011 at 21:54

Thursday, Mar 10, 2011 at 21:54

If the battery has a shorted cell it could be drawing all the power from the Power Supply - and getting VERY hot.

FollowupID: 720231

Follow Up By: oldtrack123 - Friday, Mar 11, 2011 at 11:33

Friday, Mar 11, 2011 at 11:33

Hi
I would agree with Mike
The FIRST thing to do is disconnect & check your battery
The SECOND thing to do Is with the just the battery disconnectedcheck lights & player,etc
I think you will find every thing works OK
Checking radio is a waste of time!
It's small additional load is not the problem
If the battery is stuffed then blame your power supply it probably has not maintained your battery @ full charge.
Suggest you have it replaced with a good stage multi charger

Peter

FollowupID: 720258

Follow Up By: oldtrack123 - Friday, Mar 11, 2011 at 11:36

Friday, Mar 11, 2011 at 11:36

Hi
I cannot edit ,

What brand , model, is the power supply??
Van Brand?

Peter

FollowupID: 720259

Follow Up By: oldtrack123 - Friday, Mar 11, 2011 at 20:42

Friday, Mar 11, 2011 at 20:42

Ffarouk posted:
To my knowledge you do not necessarily need a battery to be installed as the transformer is wired into the 12v circuit and even if the battery was suspect if the transformer was working there would still be lights and CD player, so I would suggest a problem with transformer.
Suggest you disconnect transformer and wire a battery charger into circuit and see what the result is.
Colini

Hi

WARNING
i would strongly advise against this.
If you do not have a battery connected to the charger, the high output voltage could easily damage electronic components.
It is true a regulated supply does not need a battery to function while on mains power,
However, If you do have a battery fitted, I would suggest you follow my post above
Doing this will show
[a] with battery disconnected from the regulated transformer rectifier source & 240v power on ,that the reg power source is "ok" & that you do not have a problem in the 240v wiring
[b] a check of the battery voltage while not connected will show it's state of charge or possible other problems such as an internal short
Peter

FollowupID: 720303