Voltage regulator: how does it work?

[earckens]

When measuring on the output of the regulator I get 3.4V. The fuel gauge indicator works pretty accurate, the temp gauge measures too low (40° C with warm engine).

How can I adjust the voltage regulator?

 

Thanks!

Erik

 

[Lebro]

If you are measuring this with engine running at 1000 + revs, then the dynamo is not working. BUT ---

 

Do you mean the main battery charging regulator as in your photo,

or the small voltage stabiliser which feeds power to the fuel, & temperature gauge ?

 

If the latter, you would not normally need to adjust, but there is a small screw in the back (usually sealed with varnish) which will alter the average output voltage.

 

If fuel gauge reads OK, then may I suggest that your car may be running cold due to failed thermostat.

 

Bob.

[earckens]

The dynamo works because the battery gets charged; I thought my photo shows the voltage regulator ? Did I measure at the wrong place?

 

Yes, I mean the voltage stabiliser (for fuel and temp gauge), I wonder now where that is situated?

 

Since the fuel reads ok but the temp gauge not: shows °30-40 (the engine runs 70-80°C warmed up). The temp sender at the engine block reads ok: I measure voltage dropping as the engine heats.

 

Thanks!

Erik

[Lebro]

The fuel gauge & the temperature gauge both use a stabilised voltage to eliminate variations in reading due to changing engine revs / battery voltage.

The stabilizer is in a small metal can (approx. 40mm X 25mm) with two terminals on it.

It is situated behind the dashboard, usually clamped to the rear of one of the gauges. It connects to ground via it's metal casing.

It is a crude device employing a bimetal strip, which heats up when ignition is switched on, & when at a certain temperature, it disconnects the feed to the gauges (& it's self), as it cools down it reconnects, and starts to heat up, & so on.

This all happens very rapidly, & results in a fairly constant average output voltage. The rapid on / off output is smoothed out by the gauges.

 

If Fuel gauge is definitely reading OK (empty tank = E on gauge, & full tank = F on gauge), then I would suspect something else, e.g. sender, or a badly calibrated gauge.

 

To measure the output of the stabiliser you will need to use an analogue voltmeter (avo 8 etc) to average out the pulses. A digital one will not give a sensible reading.

 

Regarding the main battery charging voltage regulator - don't touch it !!

 

Bob.

[earckens]

Oh great! I had been looking at the wrong place, thks for the advice. Good to know about the analog meter.

 

Do you have to unscrew the dashboard to get to the regulator?

Would you consider exchanging this bimetal regulator with an electronic one a violation of the originality of the car?

 

I will be able to do the checks only in a few weeks time when we will be back in Southern France; I keep you posted.

 

Erik

[Lebro]

 

Do you have to unscrew the dashboard to get to the regulator?

Would you consider exchanging this bimetal regulator with an electronic one a violation of the originality of the car?

 

Just the centre panel, it should be behind there.

Some people do that, I could not possibly comment !!

 

Bob.

[earckens]

I have a fascia as the one at the bottom, walnut cover. So I guess I have to take that off and look behind the plate number 61?

 

 

[RogerH]

Hi Erik,

on my TR4 the voltage stabiliser is in the righthand footwell in the top forward corner and not behind any panels.

 

The electronic version works well and is inexpensive.

 

http://www.moss-europe.co.uk/relays-switches-tr4-4a.html

refer to the left hand picture. Look at the roighthand side of the car. Second component up from bottom

 

Roger

Edited November 15, 2016 by RogerH

[boxofbits]

Hi Erik

 

You might try and earth the wire connected to the Sender Unit at the thermostat housing, and note if the temp guage rises to maximum as it should.

 

I would be suprised if your engine is running at 40 degrees or less, so if the guage functions with the aforementioned test, and your fuel guage seems fairly accurate, then the temperature Sender Unit could be faulty.

 

Regards

 

Kevin

[earckens]

Hi Erik

 

You might try and earth the wire connected to the Sender Unit at the thermostat housing, and note if the temp guage rises to maximum as it should.

 

I would be suprised if your engine is running at 40 degrees or less, so if the guage functions with the aforementioned test, and your fuel guage seems fairly accurate, then the temperature Sender Unit could be faulty.

 

Regards

 

Kevin

Hi Kevin,

 

that's what I will do; I will keep you posted: the car is in France, we go there middle of december.

 

RogerH: this one http://www.moss-europe.co.uk/voltage-stabiliser-positive-earth-128484.html?assoc=115775 ?

 

I thought that was the original "old" one. And I have a LHD drive, wonder where it sits on that one?

 

Thanks!

Erik

[RobH]

In case its any help, there was a thread a couple of years ago which dicussed temperature gauges and senders in some detail :

 

http://www.tr-register.co.uk/forums/index.php?/topic/39702-tr4a-temperature-sender-resistance-a-favour/

[earckens]

In case its any help, there was a thread a couple of years ago which dicussed temperature gauges and senders in some detail :

 

http://www.tr-register.co.uk/forums/index.php?/topic/39702-tr4a-temperature-sender-resistance-a-favour/

Very nice! Thks, Erik

[stuart]

The regulator sits in the upper right hand corner of the right hand footwell on both right and left hand drive.

Stuart.

Edited November 16, 2016 by stuart