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Voltage Stablisers (Take 3)


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Sorry to bring this subject up again but I am determined to get to the bottom of it. I have recently been having problems with my voltage stabilisers (Moss) they either fail or output a low voltage so I thought I would try an alternative source. When I test my current purchase just using the vehicle battery it shows an input of just under 12V and an output of 9.5V (no problem) however when I then connect it to the instrument cable that output drops to 5V. I am testing this on the spade connection between the stabiliser and the instrument lead not at the instrument it self. There must be a problem somewhere but not being a electrician I haven’t got a clue

 

HELP

 

 

Chris

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Sorry to bring this subject up again but I am determined to get to the bottom of it. I have recently been having problems with my voltage stabilisers (Moss) they either fail or output a low voltage so I thought I would try an alternative source. When I test my current purchase just using the vehicle battery it shows an input of just under 12V and an output of 9.5V (no problem) however when I then connect it to the instrument cable that output drops to 5V. I am testing this on the spade connection between the stabiliser and the instrument lead not at the instrument it self. There must be a problem somewhere but not being a electrician I haven’t got a clue

 

HELP

Chris

 

That indicates that you have a fault elsewhere, probably a short or near short, and it is that fault which is causing the stabilisers to fail/read low.

Disconnect one of the instruments connected to the stabiliser and see waht happens to the volts, reconnect and then disconnect another and so on.

If that doesn't produce an indiaction of the fault then you have a wiring problem, you should be able to find that by eyeball , if not come back and someone here will probably hav already given you the answer!

 

Mike

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Hi Chris,

Are you anywhere near the west country (N Devon). If so I would be willing to have a look (electronics used to be my game until the hands got less steady and the components smaller). :(

Nigel (with TS952)

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Hi Chris,

Are you anywhere near the west country (N Devon). If so I would be willing to have a look (electronics used to be my game until the hands got less steady and the components smaller). :(

Nigel (with TS952)

 

Nigel

 

Thanks for the offer unfortunatly I'm based in Bucks

 

 

Chris

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  • 2 weeks later...
Hi Chris, are you interested in originality??

If not, you could always do what i did and bought a Solid-State voltage stabiliser. It uses modern electronics and came on reccommendation to me as a lot more reliable.

 

David

 

I too would recommend a solid state voltage stabiliser (find them on eBay) however, as others have suggested, I suspect you have another problem somewhere which you will need to find first.

 

You may find one of the wiring diagrams here useful as they are in colour. American site but the diagram matches my car so assume it will yours http://www.advanceautowire.com/tr24a.pdf

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I bought a new stabiliser on ebay which when I tested on the vehicle battery had a steady 12.5 volts going in and 9.5 coming out when not connected to anything but when connected to the instruments they barely registered and on checking the output voltage had dropped to 4 volts. I have tried connecting to the temp and fuel gauge separately but get the same result. I now find that the units input and output are now the same when not connected to anything. I also have three units purchased from Moss two of which outputs zero and one which acts in the same way as my ebay purchase. I am assuming that the instruments require 10 volts to show correct readings. I agree that I probably have another problem that’s needs sorting first my problem is finding out what that could be

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I would suggest that you either have a short to ground, or at least a low resistance to ground, which is causing too much current to flow through the voltage regulator, destroying it.

 

Use an ohm meter and trace the wiring back to the instruments looking for shorts or other issues.

 

If you dont have an ohm meter, then you can use a 12v indicator bulb. Connect this to 12v, and the other part of it to the circuit you want to test - a short or low resistance will make it glow, brightly for a full short, and at varying levels for low resistance. The guages should not cause it to illuminate on their own as they are fairly high resistance.

 

By disconnecting parts of the circuit hopefully you should find one that causes the illuminated bulb to go out - this is the faulty one.

 

mike

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Chris,

I am not sure if this has been mentioned but make sure the body is earthed well, I would certainly try an extra earth wire even if it is a temporary one, as a poor earth will stop them working correctly.

Nigel (with TS952)

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RESULT

 

Just to let you all know that I have now cracked my stabiliser problems. I have now had four units from Moss all of which output 4.25 volts which means that the instruments barely register. The unit I bought from ebay initially on test showed 9.5v however when connected to the instruments this dropped to 4 volts so same problem. I tested the wiring and the instruments with the help from a ex Lucas engineer and everything was fine. I had bought some stabilisers from a company called RS Components which indecently cost 60p (minimum order 5) Moss price £8.47 ex vat & postage (minimum order £10). These stabilisers do not come as a built unit so you need to get your soldering iron out I then rewired so each instrument is controlled by its own stabiliser and bingo! Everything is fine

 

Chris

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RESULT

 

I had bought some stabilisers from a company called RS Components which indecently cost 60p (minimum order 5)

Everything is fine

 

Chris

 

I am pleased about that, and a write up would be great as suggested!,

I am really writing to say your comments on RS gave me a grin. "Some company", just one of the largest of its type, a bit like saying some car company called Volkswagen. And the thought that RS was actually cheaper than anyone esle was a bigger grin for me. As I am sure it was to anyone else who knows them. On the other hand order by 4 pm and you have it next day,

Anyway now its official: MOss must be expensive if tehy cost more than RS.

 

 

MIke

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They do come as small chips so you do have to make them into a unit. Added value and all that

I am pleased about that, and a write up would be great as suggested!,

I am really writing to say your comments on RS gave me a grin. "Some company", just one of the largest of its type, a bit like saying some car company called Volkswagen. And the thought that RS was actually cheaper than anyone esle was a bigger grin for me. As I am sure it was to anyone else who knows them. On the other hand order by 4 pm and you have it next day,

Anyway now its official: MOss must be expensive if tehy cost more than RS.

MIke

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Good idea however I'm off tomorrow to Cambodia tomorrow for three months work ( just as I have got the TR sorted) so unfortunalty it will have to wait for my return.

 

Cris

 

That's a good solution (especially the price) and sounds like the basis for a useful TRaction article Chris.
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