20 replies to this topic

[GreaseMonkey]

Hi,

I have a Smiths volts gauge that I'm wanting to test, I have opened the gauge up to have a little look and it seems that the little wire inside is very slightly singed. I tried getting a picture but the camera would not focus.

I was wondering if I could give the gauge a quick test by connecting it to a battery? Would it need a voltage stabiliser? I have a feeling that the gauge may be a dud.







I'm unsure what each terminal needs to be connected to, there are no obvious markings

Any help appreciated

Thanks

Edited by GreaseMonkey, 07 February 2009 - 04:29 PM.

[L400RAS]

I test mine with a small 9V battery first (those rectangular smoke alarm ones..)

Obviously the gauge wont swing all the way to 12V, only 9, but gives a quick indicaiton if the gauge is working.
I dont think it matters on polarity - live & ground etc.

HTH
Ryan.

[lrostoke]

The polarity does matter, if you wire them wrong way the needle definitly won't move up, If this happens just try wires otherway round.

You could check if any of the terminals look to be insulated from the casing, this will definitly be positive.

Edited by lrostoke, 07 February 2009 - 05:20 PM.

[GreaseMonkey]

Thanks for the replies,

I tried testing it with a 9v battery and after all

It does work

I tried the wires both ways and it seems to work either way?

Thanks

[lrostoke]

strange never had one work both ways guess some are different

[GreaseMonkey]

I double checked and it does seem to work either way, is it supposed to?

[L400RAS]

I double checked and it does seem to work either way, is it supposed to?

Yes, it works on a measured resustance and bimetallic strips etc, the more voltage you have, the more current goes through the gauge, the stronger the pull on the needle. doenst matter which way the current is flowing.

Ryan.

[GreaseMonkey]

Many thanks

[GreaseMonkey]

Also, as you can see from the picture the gauge is missing its glass and could do with a new chrome bezel. Is there supposed to be a Neoprone seal between the glass and the face of the instrument? I have seen it mentioned before

Thanks

[lrostoke]

ha ha I mustn't have had my tablets last time I used my voltmeter, could have sworn it would only work connected one way, but just checked it again and it does indeed work both ways
Even checked if the casing took an earth feed off the negative for the light, but they are both insulated from the case by a rubber bung in the case.

[GreaseMonkey]

That clears it up then

Many thanks for all the help

[L400RAS]

Also, as you can see from the picture the gauge is missing its glass and could do with a new chrome bezel. Is there supposed to be a Neoprone seal between the glass and the face of the instrument? I have seen it mentioned before

Thanks

Hi GreaseMonkey,

The chrome bezel is held by 3 tabs to the rear - slightly prise these up a bit, then turn the bezel round to line up with the slots on the case and the bezel should drop off. The neoprene seal should fit in the rear of the bezel, the seal stops the glass rattling. To source a new piece of glass i suggest buying any 2" broken gauge (ebay) for spares. Brasso the glass to a good shine. Your current chrome bezel would come up nearly new with brasso too!

Ryan.

[GreaseMonkey]

Many thanks, I have managed to get the bezel off finding no neoprene seal underneath. I have managed to find a place that sells glass and bezels but cant find the neoprene seals for sale but I may go with the idea of scavenging it off another broken gauge as I need other bits as well.

Also with my gauge right around the edge the black paint has come off abit and you can very slightly see the metal underneath when the chrome bezel is on, The paint on the rest of the black part of the gauge is not glossy/shiny but not a matt finish either? Its more of a Satin finish Seeing a Smiths gauge you would know what I mean

What type of paint do you reccomend to touch it up?

Also I have found a place that sells bezels and glass but no where that sells the neoprene seals, does anybody know of anyone that does?

Many thanks

Also just to add, the reason I want a new bezel is because the current one has a dint in it which you can see in the pictue (6 o'clock position) which is a shame as the rest of the bezel is perfect!

Edited by GreaseMonkey, 07 February 2009 - 08:37 PM.

[jonny d]

never mind trying to find the neoprene seal silicone sealant will do between the glass and the bezel so that you don't get it on the reverse
of the glass.

[dklawson]

I use satin or flat black paint from the hobby-shop to touch up gauge faces. Look near the plastic models and you'll probably find a bunch to choose from.

I don't use silicone sealant on gauges because it's too permanent. I don't know if you have this product in the U.K. but if you have screen doors, the DIY center probably has supplies to replace the screen. One component is window screen spline. It's like hollow tubing made of vinyl with a splined (not round) outside diameter. It comes in many different sizes. I forget which size I use for the 52mm gauges... but 4mm comes to mind. Cut a ring of that to go between the glass and the bezel. When you put the bezel back in place the spline will push the glass away from the chrome and against the gauge. Again... it's removable.

As others noted much earlier in the thread, MOST voltage gauges are polarity sensitive, Smiths are not. Smiths volt gauges (like almost all late model Smiths gauges) work by resistance heating of a bimetallic element hooked to the gauge needle. The internal resistance heating wire does not care which way the current is flowing.