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Voltage regulator


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Posted (edited)

A little confused which isn’t difficult.

My temp and fuel gauge have stopped working a few times then come back again. After the last time I decided to swop out the regulator for one of the new solid state ones off eBay.

IMG_8777.thumb.jpeg.8331d3eb6a4a049de7de7a6cee0d4940.jpeg

not too bad a job to change laying in an awkward position looking up behind the dash. 
Job sorted went out for a drive and my full petrol tank is now reading half empty and the temperature gauge only reads at the end of the blue section. Where before it ran just above half way.

I’ve just pulled it out again thinking it’s faulty but testing it gives just over 10 volts as expected. 
 

luckily I’m a hoarder so hadn’t binned the old one which when tested puts out the same 12v + put in.
So pulling it apart the wire wrapped around the  bi-mettalic strip had nearly all disintegrated.

IMG_8779.thumb.jpeg.37c3cc0c5c57ec46d3d0ed752c37907f.jpeg

this means it was just connected constantly feeding 12 plus volts.

should I just solder the strip together and stick it back in or is there something else going on ? 

 

Edited by Mickfrad
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That’s weird. How old is that regulator?

 

mick Maher had an issue with his catching fire a couple of weeks ago, one of the new style stabilisers that was around 3/4 years old…. Could be a bad batch of them. 
 

is that last picture a genuine one?

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Yes the last picture is the one I took off and took apart. It has the Opel logo and part number on it so guess it’s original. The new one I bought last year when it started playing up. Bench testing it seems alright though. 

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1 hour ago, Mickfrad said:

Yes the last picture is the one I took off and took apart. It has the Opel logo and part number on it so guess it’s original. The new one I bought last year when it started playing up. Bench testing it seems alright though. 

The original one will be toast then. They burn out over time, and I’m surprised yours has done this long! As for why your fuel and temp gauge are iffy, maybe you have two separate issues? 

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I saw Mick’s corroded dashboard on Facebook and assumed that due to the lack of heat sink that the solid state regulator had run into thermal overload and melted before the fuse for the dash blew. 
I’ve just had a quick look at specs for a fairly standard regulator it seems that good quality ones are short circuit and overload protected. E.g.

https://uk.farnell.com/texas-instruments/ua7810ckcs/voltage-regulator-fixed-10v-to/dp/3122756

the old LM7810’s are similar and should be ok for 1.5A drain, the fuel gauge and tank gauge should be drawing much less than that. I’d estimate milliamps. In a short circuit or thereabouts I am wondering if the heat of the I.c. melted the heat shrink sleeving it’s covered in and the tracks of the small PCB with the spade connectors may not cope with that current hence heat and smoke. 
 

On to the issue at hand. Is your alternator charging at 13.8V? Is that voltage getting to the regulator? If the specs in the link above are equivalent, the regulator may not be giving 10V under load if 12.5V that is not available on the dash. 

It may be worth putting a multimeter lead from the -ve on the battery to the earth track on the dash with it switched on and measure if there is any voltage difference. 

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a basic check on temp guage ( or fuel sender for that matter would be to put a 40ohm resistor to the connector and to earth. this should give an approximate half guage reading . mine  all have the original thermal voltage regulators fitted and i have a good few spare ones ( except the carlton which is electronic as standard) 

your new ons mag be faulty or it could have missed the pinhole when installing ? 

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and as regards mending the old one you wouldnt be able to rejoin the heating wire as it will be too brittle . soldering obviously wont work . only thing would be to see if it would crimp but i doubt it. putting it back in faulty however should result in both guages actually working but giving too high readings . this would at least prove the system works . otherwise its a new oe regulator, new electtonic one ( or just make one yourself . i have the basic diagram of the carlton oe one if req)

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I will check voltage at the regulator when it’s plugged in when I get a chance. Pretty sure alternators ok.

5 hours ago, cam.in.head said:

and as regards mending the old one you wouldnt be able to rejoin the heating wire as it will be too brittle . soldering obviously wont work . only thing would be to see if it would crimp but i doubt it. putting it back in faulty however should result in both guages actually working but giving too high readings . this would at least prove the system works . otherwise its a new oe regulator, new electtonic one ( or just make one yourself . i have the basic diagram of the carlton oe one if req)

I think it has probably been broken for a long time and just feeding the 12 + voltage to the gauges. As far as I was concerned the gauges were reading accurately at that voltage. Which is why I was thinking of making a permanent connection across the pins on the old one to stop it cutting out. Not sure what detrimental effect this could have on the gauges and why they appear to be working correctly at the higher voltage. 

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i cannot understand why the guages would work normally with a faulty regulator .this isnt realy possible .because they could be fed with anything from a tad under 12 volts up to 14.3 ish depending on revs / battery/ alternator  load so the guages would be all over the place!

i would be checking the connections on the back of the dash and any earth connections although i must admit that i cannot remember where the dash earth connection actually is ? ?

the fuel guage sender and temp sender are totally isolated units so why both read low is very puzzling. tank senders are pretty reliable although the earth connection on hatches is always rusted away.( coupes / saloons not an issue)  temp senders seem pretty reliable too ( different brands can give slightly different readings)

the carlton dash ( senator ,monza) use a built in regulator on a clip in heatsink. its a ITT TCA700Y .12v is fed into terminal 3, negative into terminal 2 via a 10 ohm resistor and the output to the guages from terminal 1.

 

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  • 2 weeks later...

Finally had a chance to spend some time on the car today. 
Just over 14v from the alternator same behind the dash 14 in 10 out.

Put the broken one back in and both gauges went up as expected with the extra voltage. Temperature gauge now reads just over half way and petrol gauge went up about half way. Went out for a run topped the petrol up and gauge shows full tank.

 No fluctuation of either gauge. so still none the wiser.
My charge light wasn’t working but came on today and now won’t go out even though alternators showing 14v something else that needs fixing. 
 

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26 minutes ago, Mickfrad said:

Finally had a chance to spend some time on the car today. 
Just over 14v from the alternator same behind the dash 14 in 10 out.

Put the broken one back in and both gauges went up as expected with the extra voltage. Temperature gauge now reads just over half way and petrol gauge went up about half way. Went out for a run topped the petrol up and gauge shows full tank.

 No fluctuation of either gauge. so still none the wiser.
My charge light wasn’t working but came on today and now won’t go out even though alternators showing 14v something else that needs fixing. 
 

Definitely odd, we all know the cluster is designed to work at the regulated 10v, so definitely odd. But you do gave some funky things going on. Have you another cluster you can test with?

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yes definately odd especially if the original is  now back in albeit broken . im sure that you will find that at idle with the lights on blower etc the guages will come down and then go up with increased revs / voltage . so in reality it sounds like your engine is either running too cool or the sender unit is faulty and similar theory with the fuel guage ( especially if a hatch with the extra earth wire).

also with a conventional thermal voltage regulator you can do a basic test by tuning inbetween radio stations on AM and after 10 or so seconds yoh will hear the voltage regulator clicking through the radio speakers !

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On 17/06/2024 at 22:32, Mickfrad said:

Finally had a chance to spend some time on the car today. 
Just over 14v from the alternator same behind the dash 14 in 10 out.

Put the broken one back in and both gauges went up as expected with the extra voltage. Temperature gauge now reads just over half way and petrol gauge went up about half way. Went out for a run topped the petrol up and gauge shows full tank.

 No fluctuation of either gauge. so still none the wiser.
My charge light wasn’t working but came on today and now won’t go out even though alternators showing 14v something else that needs fixing. 
 

I’m still not sure how or why but my charge light was being fed current from both ends! A friend who understands these thing said “put a diode in that wire there”. I’m sorry I can’t remember which wire and I can’t check as it up behind the dash somewhere. I asked him what diode rating I needed and he said “oh any”. It all seemed a bit casual but I did what he said and now it’s all working as it should.

These are the diodes I bought;IMG_1362.thumb.png.6a9aae67b2db9383c9dd93fcee22b142.png

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the charge light ONLY connects to the alternator , nothing else and gives the light a negative circuit through the alternator until it produces a positive voltage (running)which means -no potential difference hence no light- so providing its plugged into the correct terminal it sounds like the alternator has a minor issue with the regulator or diode pack that adding another inline diode is masking the fault. if its working now this way and causes no issues then it may continue to work for somewhile ( or for ever ) but something is amiss .

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Posted (edited)

I dropped a spare alternator that wasn’t charging off at a company near me for a refurb yesterday.
He says the brushes are probably gone so he’ll check everything and call me next week. It’s a 70amp Delco remy so worth getting sorted. 

The one currently on the car that the charge light stays on and gets brighter when revved, he says is a faulty diode so I may drop that off next to get sorted so I have a spare. Depending how much it costs to get the first one done. 

Even with the Alternator pushing 14.3 volts my gauge doesn’t get off the yellow. Is that normal for people or is that potentially another dash issue. 

Edited by Mickfrad
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On 19/06/2024 at 19:09, Jonathan Pounsett said:

I’m still not sure how or why but my charge light was being fed current from both ends! A friend who understands these thing said “put a diode in that wire there”. I’m sorry I can’t remember which wire and I can’t check as it up behind the dash somewhere. I asked him what diode rating I needed and he said “oh any”. It all seemed a bit casual but I did what he said and now it’s all working as it should.

These are the diodes I bought;IMG_1362.thumb.png.6a9aae67b2db9383c9dd93fcee22b142.png

 i understand what your electrician means about current from both ends !    however he may have missed the principle.

as explained above once you get a voltage at both ends (once the alternator starts producing voltage ) there is no "potential difference / ie the light doesnt light because it has +voltage on both pins . it lights when engine not running because it has + voltage on 1 pin and negative ( through the non turning alternator) on the other pin. 

sticking a diode in a dc circuit does absolutely nothing ( drops it very slightly !) so it sounds like a alternator internal issue.

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  • 3 weeks later...

Does somebody know where the dash earths, as I’d like to get to the bottom of this. Main problem now other than feeding 12v to the temp & fuel gauge is the voltage not coming off the orange section when I know the alternators kicking out 14v.

Not a major issue I know but annoying nonetheless, I know I’m going to have to pull the dash out and have a look at some point but probably a job for the winter. 

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