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Totally off topic but there is some knowledge on here about 12v systems so maybe someone can help as I’m limited on elastictrickery.

I’m trying to sort the electrics out on our German ( I can’t find anything online about it ) caravan and we have a distribution panel which brings a 240 & 12 v input, then distributes it via a 240v and 12v outlets.

 

it looks to be a simple set up but the 12v side isn’t working on the outlets. 
 

ive tested the transformer and it’s outputting 13.7 & 14.2v but after these 2 objects there is no voltage so I’m assuming these are at fault. 
 

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can anyone explain what they are and how I could get replacements? 
 


 

cheers

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They look like relays, they might be perfectly OK, and it's the operate circuit that is broken.
I think your best is to give people more detail of your 'German caravan' (name, model, etc), in the hope that someone else has details, and can help more directly.

Does the 'device' containing the fuses, circuit board, etc, have words on the cover, box, or whatever? (Because the same unit might be used in other caravans, motorhomes, etc).

Regards.

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They are relays without covers. The primary side (low current) is the coil that you can see in each. At the front left corner as shown, you can see the switched contacts that carry the secondary circuit (probably higher current) and they will go through the fuses.

The relays should at least 'click' when they are energised (through the coils). That click will move the contact across the tiny air gap. You should be able to trace the circuit from those contacts to see where it comes from and goes.

Edit: just mind your fingers on the 240VAC stuff

Edited by Peaklander
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Ok, thank you all, the caravan is a Hobby 620 Prestige, circa 2003.

I'll try to energise the relays when I get back, here's a picture of the complete unit but no labels with a model number on them

 

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except this one

 

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It allows for direct connection of 12V from a battery to the load. When hooked up to mains and switched on, it provides a 12VDC source and the relays swap over to connect the load to it rather than the Aux battery. 

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I might add, after reading that document (using google translate), that the author isn't impressed with the unit. When switched to the AC feed, the 12V output is either at AC, "for lights etc." or a not very well rectified DC which isn't smooth enough for some electronics. That AC for the lights won't be useful for any led lamps. Maybe swapping in a good 12V power supply would be a better option.

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On 4/14/2021 at 10:08 AM, HoSS said:

Theres no rectifier on the board, it is AC. 

Why have you said that? There are two diodes fastened to the heatsink, although no smoothing capacitor. There is rectification, it's just a horrible result.

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2 hours ago, Peaklander said:

Why have you said that? There are two diodes fastened to the heatsink, although no smoothing capacitor. There is rectification, it's just a horrible result.

Both are true, if you look at the wiring diagram only the 7.5Amp fused circuit uses the diodes, the two 10Amp circuits bypass the diodes and are marked as 12AC

And if you look at Page 5 in the diagram it shows both wave forms and if you translate some of the sentences it says

 

Quote

Consumer circuits III and IV are supplied directly from the transformer without rectification. So here is 12 V AC voltage and no DC voltage! That is only enough for lighting with lightbulbs and other undemanding consumers.

 

Edited by zardos
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It also says,

The consumer circuit I and II is an AC voltage rectified by the rectifier (a powerful Schottky diode). Here the voltage curve pulsates 100 times per second between 0 and 18 V. So no real DC voltage either. That is usually enough for pumps etc. A radio would hum nicely, a 12 V TV set would probably not produce a picture at all.
The 12 V outputs I and II are protected by a 7.5 A flat fuse.

There are rectifier diodes but no smoothing capacitor and no voltage control/stabilisation and so 'a horrible result' which is highly fluctuating and isn't much use at all. The author acknowledges that later Hobby caravans were fitted with a much better supply. I guess that's what @Badger110 will do.

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Ok didnt see them, and as there was no bridge. So its full wave rectified, but no smoothing or regulation.

It will be pulsing at 100Hz and the voltage will fluctuate with load. Some things wont like that.

You could add a smoothing capacitor, even a regulator, but it depends what kind of load you are drawing.

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Thank you all for your knowledge in working out what I have and what it can do.

 

Originally the caravan was going to sit on our land and be used as an extra living accommodation at certain times of the year and be connected to a 240v feed permanently so there was no need to worry about the 12v side of things. 

 

However, times have changed and we have now decided to use it as a touring caravan to be located around the country and Europe at certain times and become a base as we travel and I was looking to reinstate the original wiring set up.

 

Looking at this unit, it is dated and although fit for the purpose of the caravan itself ( it's a ' dry ' caravan so has no set up for sinks, toilets, pumps etc ) I will need to look at a more modern version which will work with pumps, water heaters and radios as well as be able to charge the battery from the Truck when towing.

 

I will put this to one side for now and look at a suitable set up and if anyone has any recommendations, I'll happily listen to them :)

 

 

 

 

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