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Voltage stabiliser


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I'm trying to replace the voltage stabiliser on a 7, the original has 4 seperate terminals marked T,I,E & B, l can note find a replacement. Most other Triumph use a stabiliser with 2 terminal pairs marked I & B. Has any one come across this problem and has a solution.

Andy

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This has been discussed some years ago Andy (link below)  - the TR7 apparently doesn't have an instrument voltage stabiliser so its not clear what the module is that you are asking about. Could it be a modification I wonder?

 

Edited by RobH
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Thanks for all replies.  Not sure if this helps. The fuel gauge is not working and l thought l would start at the gauge before checking the tank unit. The voltage stabiliser is a Smiths BDS 1004/00 mounted under the top dash cover above the instrument pod with 4 wire connections from the wiring loom: Green red terminal I, Green pink terminal L, green paired terminal B. Black paired terminal E. As Peter mentioned it could be a low fuel delay unit and hard to find. Can anyone suggest the next move.

Andy

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A pretty good wiring diagram is here:

https://drive.google.com/file/d/0B0OCjgNgn85aOEdlYWp6dnFfc2s/view

Yes that number is the delay unit also called UKC7096

As you can see from that diagram (page5) the fuel tank transmitter has two outputs - one for the warning lamp and another for the fuel gauge so the module shouldn't affect the gauge readings as it's a separate circuit. It wouldn't hurt to disconnect the green/orange wire though and see it if makes a difference. 

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Andy,

 

This might help.

http://www.tr7triumph.com/forum/viewtopic.php?t=24330

(It even shows what is inside !)

Charlie

Edited by Charlie D
Spelling.
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Thanks to all for your input, after much googling have confirmed it is a relay not a voltage stabiliser  UKC7096. Looks like their only available from the US for about £50.00.

Regards

Andy

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Hi,

  In the 1982 part book (RTC9828CC) it listed under that number but the 1977 TR7 & TR8 part book (RTC 9029B) have 2 part number

the other being TKC4017. Give that a try and see what it come up with. 

And Yes I do have a lot off parts book. And I see you come from Surrey and have a Marco a old friend off my use to live in Reigate

and had a Marco in about 1974 I love that car at the time.

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Hi Peterh

Thanks for your efforts. Every search shows that UKC7096 is no longer available in the UK, l will contact Revingtons in the morning just in case otherwise the USA is the only solution.

I had my Marcos in the seventies. it was the 1967 Motor Show car, reg # LAM 100F, a recent search shows it burn out no longer around.

Regards 

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Andy - are you sure you aren't going off on a tangent ?  You told us originally that the fuel gauge wasn't working. The relay you are trying to obtain doesn't affect that - it just controls the action of the low-fuel warning lamp. Replacing the relay probably won't make your fuel gauge work. 

Edited by RobH
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RobH - Nether the low fuel warning lamp or gauge are working, all the panel bulbs are OK.  I remove the Green/orange lead tomorrow.

Thnaks for your input

Andy

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If that makes no difference I think my next check would be whether the tank sender has a decent earth connection.  

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Its not a relay - its the delay unit.

if memory serves:-

You should be able to jump the input (from the sender) to the gauge and get the gauge working. There will be a bit of an offset on the gauge due to not having the heater in the circuit. I don't know how much that effects it but its probably not much.

If the wire in the delay unit breaks then you will loose both indicators.

 

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Alfie,

have you tried talking to either Robsport or SS who both deal with TR7 second hand parts and restoration and servicing of TR7 specifically?

Regards

Ian

 

 

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1 hour ago, Melcoagain said:

You should be able to jump the input (from the sender) to the gauge and get the gauge working. There will be a bit of an offset on the gauge due to not having the heater in the circuit.

The circuit diagram shows the two circuits as being separate in which case that won't work. The delay unit heater is not in series with the gauge and connects to a different terminal on the tank sender which is probably just make/break contact.

 

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2 hours ago, 71tr6 said:

Merlin motorsport list this delays switch for £11.60. HTH

Hi, There is some confusion regarding this unit, its not a voltage stabiliser its a warning light relay (UKC7096) although it looks the same but the connections are different. The unit on Merlins site is a voltage stabiliser.

Thanks for your input.

Andy  

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RobH might be right. I don't have  a circuit in front of me.   Many of the circuits don't show the sender internals so its hard to tell. I still think its in series. 

But i reiterate that its a delay unit not a relay. If you fit a relay the warning light would come on every time the sender float dropped. That's driving up hill and going round bends with about a quarter of a tank.

Some sources may list it as a relay if they are not clear how it works or the typist thought it was misspelt.

If you earth the signal to the gauge it should go full deflection. 

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I posted a link to the circuit diagram in a comment above if you need that, but as you say it doesn't show what is inside the sender. It does show two separate and differently-coloured wires running to the delay unit and the gauge respectively so they are not connected. The best detail I could find is the photo here:  https://www.ebay.co.uk/itm/Triumph-TR7-TR8-FUEL-GAS-TANK-SENDER-UNIT-with-lock-ring-and-seal-Petrol-/293171024664.  which shows the sender has two separate output connections in addition to the earth tag.

 

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Continuing saga of the fuel gauge. The 7 is a new acquisition with lots of history, rust free body all mechanics good. l know the fuel gauge wasn't working. Having try all  the suggestions from members and some from Robsports. Looking at the instrument pod l can see that it has been played with so l am now going to do some bench testing, l assume that l can check that gauges and light using a 12v supply. Watch the space.

Andy 

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My understanding of how this works is as follows. The numbers are made up for the explanation as i have nothing to measure.

12v from the cluster goes through the delay unit heater coil (1 ohm resistance). Then down to the sender (1 terminal). This connects to the bottom of the sensor resistor. The top of the sensor resistor connects to earth via the terminal (2nd terminal) and to the body. Assuming the sensor resistor is 19 ohms then total resistance is 19+1=20ohms. 12v/20=0.6amps. The 0.6amps doesn't create a lot of heat on the warning light delay contact so the light is open circuit and off.

The wiper on the sensor resistor feeds through the 3rd terminal and to the fuel gauge. I will assume the gauge has a coil of 1 ohm resistance and then connects to earth at the cluster.

So when the tank is full, the float is high, the wiper is near the earth end of the sensor resistor. Not much change on the delay unit (low current lamp off), the sender output is close to earth so the gauge reads high (full).

When the tank is low, the float is low, the wiper is near the 12v end (from the delay unit). The circuit takes the path of lowest resistance so the 12v goes through the delay unit heater, then through the wiper to the gauge. So ignoring the minimal resistance of the sender resistor the resistance is 1+1=2ohms 12v/2 = 6amps. 6 amps through the delay unit makes the heater get hot and the bimetallic switch closes the circuit to the warning light (light comes on). Note the time delay while the heater warms the bimetallic strip - If the float rises again the heater goes off and the strip cools. So fuel slosh doesn't generate sufficient heat to warm the bimetallic strip.

So from the above:

If the delay unit goes open circuit (heater wire breaks) the warning light stays off but the gauge goes full.

If there is no earth on the fuel sender. The gauge shows empty and the warning light still works.

If there is a break in the sensor wire to the gauge. The gauge doesn't move and the warning light is always off.

The warning light switch level is a vague level based on the resistance in the system so quite variable from vehicle to vehicle due to tolerances.

I haven't looked at this for years but this is what i think happens. All 3 terminals are used.

 

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1 hour ago, Melcoagain said:

When the tank is low, the float is low, the wiper is near the 12v end (from the delay unit). The circuit takes the path of lowest resistance so the 12v goes through the delay unit heater, then through the wiper to the gauge

No sorry, it isn't like that at all. The low fuel connection on the tank sender is just a contact connected to the float arm stop tab and which earths when the fuel is low so that current flows through the delay unit heater. 

You can disconnect the green/black gauge wire from the tank sender and the low fuel light will still work which shows they are two separate circuits. 

See the first post here: http://tr7triumph.com/forum/viewtopic.php?t=15400

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Thanks to all for your input, no luck so far. I have been given the impression that you can not check the delay unit but l would assume that if you put a 12v supply in you should be able to get output from the other terminals, the circuit diagram seems to show 3 connections on the delay unit, l have 4 terminals marked as T,L,E,B

Green/pink wire to T, Green/red  to  L , Twin black to E, Twin green to B. I believe that black = earth, green = 12v input, so if l put 12v to green l should get a reading on either terminal T or L

You can probably tell that electrics are not my strong point.  

 

 

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Unfortunately the wiring colours you seem to have are not quite the same as those shown on the diagrams, and the pin lettering is not shown either. Both of the wiring diagrams I posted links to do show a four-terminal device.  Two are either end of the heating element and the other two are a 'make' contact.

Green should be 12v to the top of the heater element.  On the wiring diagram the other end of the element is green/orange which goes off to the tank sender (I think that is probably the green/pink that you have). If you earth that one the element should heat up and the contact should close. 

The black earth wires go to the contact and the other end of that - green/red goes to the warning lamp which is powered from 12v. 

I suspect the pins are B = battery (12v), E = earth, L = lamp, T = tank but that is only a guess.

It should be easy to test the unit off the car. 

I suggest you try by connecting 12v to B (do that via a 3A fuse just in case the guess is wrong) and earth to E.  Connect a small bulb from. 12v to L. The bulb should be off.

Connect T to earth and wait a few seconds - the bulb should light. Remove T from earth and wait - the bulb should go out.

 

You can check the low fuel dash bulb connection by earthing the green/red wire with ignition on. The lamp should light with the wire earthed. 

 

Edited by RobH
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