# Truma Sonatic L



## apprentice (Jul 25, 2007)

Good morning campers - a newbie here!

Firstly; fab forum!..... An absolute mine of info.

I've searched archives but can't get a solution to this......

I have an old style TRUMA SONATIC L control box (charcoal colour with two white buttons) which has no display/ no power to. Nice chap I brought it from suggested it had a "hearing aid battery in it" - not so when I pulled it apart.

Am I missing something fundamental? What are the conditions for it to work - ignition on etc.? Is it linked to a fuse? :?: 

Any suggestions welcomed. 

apprentice


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## DABurleigh (May 9, 2005)

apprentice,

Welcome to MHF!

Hmmmnnn. I have a flush fitting/ OEM market grey control box with 2 white buttons. Thought that was the new one and the screw-on brown/beige aftermarket one was old.

In any case, the answer depends on how it was fitted. Unless you want the display continually showing (in which case wire to 12V leisure supply), then a 9V PP3 battery is fine which is all I used. It only consumes milliamps for when you press the button to get a reading, so still works fine after 2.5 years.

Basically look behind the control unit and take things from there, maybe with a multimeter to check voltage on the wires (not the transducer wire)

Dave


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## apprentice (Jul 25, 2007)

Cheers DABurleigh,

Appreciate the advice - has enlightened me greatly.

Just to add - Nothing behind the control box, unless it's hidden in the wooden panel behind. Traced the wires down to cupboard below - nothing.

When I look inside the unit it has a separate two point connector along with a block with three screw down connectors - with one red and one black wire and the third is empty. 

No obvious place for a battery and no existing wires. Makes me wonder whether it's ever been wired in?

If there isn't one already how do I wire one in?

Many thanks,
apprentice


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## DABurleigh (May 9, 2005)

Well I'm not sure whether you have an identical model to this or not. However, it's only style anyway. You should have 3 wires - one for transducer, and two (red & black here too) connected to a battery somehow. I'm unclear from your description whether you have just 2 or 3 wires, and what is on the end of the red and black in the cupboard. What do you mean by "Traced the wires down to cupboard below - nothing" and "No obvious place for a battery and no existing wires." Another issue - is there actually a transducer at your cylinder(s)?

Hopefully the above and these pictures help. Note my wires are connected going to a 9V battery; the red wire goes to the other terminal in the block for 12V. And I only have a single cylinder connected.

Dave


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## apprentice (Jul 25, 2007)

Once again thanks for coming back.

Sorry if I am not being clear.

My unit is not the same on the fascia, however the wiring is - I have the red and the black wires, which you inform me go to your battery. I traced my red and black wires into the panel behind the unit and then traced them again in the back of the cupboard below. 

Question is where do your wires go? Once I can locate the battery then I can replace it and solve the problem.

Currently not able to confirm about transducer - may get a chance in the morning.

apprentice


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## DABurleigh (May 9, 2005)

My wires go to a 9V PP3 battery gaffa-taped on the back of the control unit. The stand-by current is miniscule. Press the button and a few mA are drawn for 10 secs or so, before dropping back to micro-amps.

Sounds like yours go back to the 12V leisure battery. Have you checked the terminals at the control box are zero volts?

Dave


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## apprentice (Jul 25, 2007)

Thanks again DAB!... and thanks for taking the time out to provide pics - really helpful.

Quick update - I have just discovered that the single gas bottle I have ain't sitting on the pressure pad! :roll: So I'll change it over.

- I can see the small black wire (two pin connector from control box) going to the pad.

- I haven't located the other end of the red and black wires, but then I haven't located a leisure battery!

- no sign of a 9v battery. 

Off shortly on a long weekend break in the Hymer, so I'll use the time when it's raining :wink: to do some more investgation and if possible I will hopefully locate a fellow camper with a test meter.

I'll let you know on my return to a PC.

apprentice


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## apprentice (Jul 25, 2007)

Back at PC now.... over 2 years later!!! :wink: 

Just stumbled across my post and thought it would be both useful and courteous (if a little late!  ) to conclude and hopefully assist others.

Subsequently brought in an electrician friend who traced the wires to an unmarked factory style rocker switch mounted in the middle of the control panel. By switching this on, I could then utilise the Truma Sonatic L.

Better late than never,
apprentice


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