Voltage stabiliser

[wheeler]

How about this then, recently my instrument voltage stabiliser caused the temperature and fuel gauges to read low. I bought and fitted a replacement solid state stabiliser. The gauges then started to read very high, fuel nearly full when tank half empty and temp gauge almost in  the red. I needed to use the car to drive to Essex. At the Dartford tunnel I switched on the headlights and the gauges read correctly, when I switched off the headlights the fault returned. I have cured the problem by running a separate earth wire to the screw holding the voltage stabiliser. I can understand a faulty earth connection. What I can't understand is how switching on the headlights could clear the fault!

[RobH]

The clue is probably in the words 'solid state',  Bill.  

Old cars like ours are a very 'noisy' electrical environment both from the ignition and the alternator, and depending on what chip is inside the stabiliser it may have been confused by electrical noise picked up due to a less-than perfect earth connection - I guess yours is mounted on the back of the speedo  and gets its earth from the dashboard?    

Your use of headlights may have loaded the electrical system in such a way that the electrical noise was reduced enough for the stabiliser to sort itself out.  

All supposition if course ............a common chip used in the stabilisers needs a couple of capacitors around it for proper noise suppression, but I believe the makers of the units sometimes omit those to reduce costs. 

 

[PodOne]

 

1 hour ago, RobH said:

All supposition if course ............a common chip used in the stabilisers needs a couple of capacitors around it for proper noise suppression, but I believe the makers of the units sometimes omit those to reduce costs. 

The bean counters strike again!

[Jules TR6]

Could anyone recommend a more 'TR6 worthy' / less particular, voltage stabiliser - link to the product please,

rather than what I'm seeing on Rimmer and most other outlets - which I assume are solid-state and do look a bit cheap.

My fuel gauge was not working when I just started the car (hence why I came to this thread). So I cleaned the v.stabiliser's 3 contacts and the earth wire connector to the speedo. Fuel gauge still not working.

Then I read if it's the v.stabiliser (and not the fuel sender) the temp gauge would also not be working. So I went back out to check the temp gauge, turned the key and lone behold the fuel gauge (and temp) was now working! Thinking maybe it's wise to get a spare v.stabiliser if it is that which is on its way out (the fuel gauge with a full tank has been reading 3/4 of late, I'm sure it used to read full/max), as I do like have the fuel gauge even though it's not 100% accurate (rather than a stick).

[michaeldavis39]

Send your original voltage regulator to the link below and this gentleman will rebuild it with quality components. This worked perfectly for me

 

https://ebay.us/m/bjHPRk

Edited August 6, 2025 by michaeldavis39

[Jules TR6]

30 minutes ago, michaeldavis39 said:

Send your original voltage regulator to the link below and this gentleman will rebuild it with quality components. This worked perfectly for me

 

https://ebay.us/m/bjHPRk

...good information. If the fuel gauge quits again - and the temp gauge at the same time, I'll go the route you suggest - keeping the original regulator case.

[PodOne]

I replaced mine with a solid state electronic replacement.

Working fine but I don't remember where it came from other than it wont have being from Rimmer's !

[Chris Hale]

This guys voltage stabilisers are fit and forget 

keith@fenwick40.freeserve.co.uk 

pretty sure this is his eBay https://www.ebay.co.uk/itm/285984352224?_skw=mg+voltage+stabiliset&itmmeta=01K20JTJ2HB7EA2TD18G1WFN3N&hash=item4295fee7e0:g:XxEAAOxyRhBS-o2P&itmprp=enc%3AAQAKAAAA0FkggFvd1GGDu0w3yXCmi1eiyaK1P4PfsTOOoSk0FVOkD96D9zFWUw%2BZvJAIuE50Gt%2Fgd2wd%2B3vGzMteXQohPNPbHC5HG8qGoy2EwEV5n0YzUY1EQNRi%2FEVGiAsQNd29n3KM8uJ5bJZhLs9G0QBXXTVlPw9N8wp%2BFMNQA2dLnbP4Re%2BJuxHsmJyAHgkiYroyTi%2B7zJ%2B59%2ByX7VJAkUp%2FghO8mh9XAUAx5GYnV3hmuOuRlmFUDQP%2B5uZDQPf5asEeSj4P%2BWofdPW992UieMj3dK8%3D|tkp%3ABk9SR56i6pKQZg

despite the advert is for those that should not be mentioned

[Jules TR6]

11 hours ago, Chris Hale said:

This guys voltage stabilisers are fit and forget 

keith@fenwick40.freeserve.co.uk 

pretty sure this is his eBay https://www.ebay.co.uk/itm/285984352224

...I liked his description of it, so just ordered.

 

Edited August 7, 2025 by Jules TR6

[BlueTR3A-5EKT]

I have a couple of new but scruffy original TR5/6 voltage stabilisers.  PM me if interested.

[wheeler]

Thanks Rob for the information. The new solid state voltage stabiliser and both gauges working fine now all be it with the extra earth, perhaps the speedometer case doesn't have a decent earth connection. I bought the stabiliser from here https://ebay.us/m/Y06LSK

Thanks again

Bill

 

 

[Jules TR6]

7 hours ago, wheeler said:

Thanks Rob for the information. The new solid state voltage stabiliser and both gauges working fine now all be it with the extra earth, perhaps the speedometer case doesn't have a decent earth connection. I bought the stabiliser from here https://ebay.us/m/Y06LSK

Thanks again

Bill

 

 

When you changed the stabiliser I assume you removed the speedo.

Of the two securing legs that clamp the gauge behind the dash, one will have an earth wire (usually on the more 'hidden' upper post I think) attached. The earth wire's terminal slides over the gauge's threaded post between the end of the (upper) leg clamp and its knurled securing nut. Is the original earth lead still in place - or it did it pop off when you got the speedo out (it's probably black so if it pops off you might not notice it hanging loose) - and wasn't reinstalled?

Edited August 7, 2025 by Jules TR6

[wheeler]

7 hours ago, Jules TR6 said:

When you changed the stabiliser I assume you removed the speedo.

Of the two securing legs that clamp the gauge behind the dash, one will have an earth wire (usually on the more 'hidden' upper post I think) - the earth wire's terminal slides over over the gauge's threaded post, between the end of the (upper) leg clamp and its knurled securing nut. Is the original earth lead still in place - or it did it pop off when you got the speedo out and wasn't reinstalled?

Hi Jules, I didn't see  an earth wire but I will have a look when I next remove the speedo 

[Jules TR6]

55 minutes ago, wheeler said:

Hi Jules, I didn't see  an earth wire but I will have a look when I next remove the speedo 

...arh well if you did remove the speedo and didn't reinstall an earth wire, it either popped off and you didn't notice it, or it wasn't there in the first place. The speedo should have an earth wire slipped over one of its two threaded leg posts.

Can you look up under the dash? Disconnect the battery for safety. Place a flattened old box on the floor to kneel on, place a torch on the footwell wedged to point up (or use a head torch), then stick your head in the foot-well and look up, have a good look around for a black earth wire - it might be around the door side (off-side) under the dash (right side of the speedo). If you are less than nimble or have a stiff neck this won't be possible, otherwise if you can do it, you will have a stiff neck afterwards! 

Edited August 7, 2025 by Jules TR6

[wheeler]

Thanks Jules, I will have a look.

Cheers

Bill

[J7nno]

Hi Newbie here.

Just purchased a TR250 with a host of problems. One issue is that the temperature and fuel gauges don’t work and reading this thread I’m thinking it’s the voltage stabiliser thing! Where do I find it and how do I get at it please!?

I’ve already changed the temp sensor to no avail ……

thanks in advance 

[DRD]

1 hour ago, J7nno said:

Hi Newbie here.

Just purchased a TR250 with a host of problems. One issue is that the temperature and fuel gauges don’t work and reading this thread I’m thinking it’s the voltage stabiliser thing! Where do I find it and how do I get at it please!?

I’ve already changed the temp sensor to no avail ……

thanks in advance 

All the usual suppliers will have them, also there's a guy on eBay who sells electronic versions. It fits onto the back of the speedo so you will need to remove this first to swap in a replacement. The most difficult part of the job is getting your hand behind the dashboard to undo the little knurled nuts holding the speedo in.

Cheers Darren

[Jules TR6]

15 hours ago, J7nno said:

Hi Newbie here.

Just purchased a TR250 with a host of problems. One issue is that the temperature and fuel gauges don’t work and reading this thread I’m thinking it’s the voltage stabiliser thing! Where do I find it and how do I get at it please!?

I’ve already changed the temp sensor to no avail ……

thanks in advance 

its here's > I'm holding the speedo upside-down... so the VS is actually located top left if looking from the front of the speedo...

maybe clean the connections first - and make sure they are tight, then try again, before ordering a replacement.

NB one of the two long threaded posts as seen above (which secure the speedo behind the dash), should have an earth wire connected to it under the knurled nut... when removing the speedo it's often not seen, pops off, then isn't reattached!

Edited September 2, 2025 by Jules TR6

[RobH]

 

5 minutes ago, Jules TR6 said:

maybe clean the connections first - and make sure they are tight, then try again, before ordering a replacement.

...also make sure the earth is good.   It is made via the mounting tag through the body of the speedo so there are plenty of places to get  a bad connection. 

[J7nno]

Thanks for your comments all. 

I have now removed the Speedo and there’s nothing connected to it !

Eventually found this little fella attached (or not as the bracket was broken) to the bulkhead behind the glove box!

As it’s physically broken I assume lack of earth is the problem. Will try  and find a new unit.

 

[RobH]

You might be able rig up an earth connection to that one  - if it isn't aluminium it might be possible to solder a wire to the case. 

[Pete E]

Just a thought, his there any reason for the VS to be attached to the speedo other than as an earthing point or is it more convenient for possible/eventual renewal?

Pete

[RobH]

No technical reason at all - I expect it was the most convenient flat surface near the gauges. 

[Jules TR6]

1 hour ago, RobH said:

No technical reason at all - I expect it was the most convenient flat surface near the gauges. 

…yes though the reasoning was probably something like this… It was a way of ensuring the VS would be installed in new cars having Smiths temp and fuel gauges. As those gauges were a bit too small to mount a VS to, rather than entrusting the car manufacturer to install a VS somewhere, Smiths took responsibility and placed the VS on their other gauge - the larger Speedo - which manufacturers were bound to also fit.