Jump to content
  • 0
OZITIM

Landrover forward control resister ballast

Question

Posted (edited)

Does anyone have any idea where the resistor ballast for the ignition coil on a landrover forward control is located. Better still, a pic of where yours is located if you have a 101. I’m not getting spark at the points when I start, although I have electricity there and it sparks manually if I put a screwdriver to arc it out. I’m told that it might be due to a wire disconnected from the ballast.. but as much as I have searched, I’ve been unable to locate it. I had spark a couple of weeks ago, i then pulled the distributor out to service it and change points. Now no spark. 
 

I have the ambulance variant of the 101 
 

any help, greatly appreciated 

Edited by OZITIM

Share this post


Link to post
Share on other sites

13 answers to this question

Recommended Posts

  • 0

The ballast resistor is inside the filter box & that will be a few inches away from the coil, given that the screened cable is quite short.

If you are getting sparks at the points it shows that there is continuity through the filter box & the ballast resistor is likely to be ok.

You shouldn't really be getting sparks at the CB points, it is the job of the condenser to minimise this & maybe you have the signs of a failing condenser. This would not only show itself by allowing sparks but the spark will erode the points (think of how an arc welder works).

The consequence of a spark is that it slows the collapse of the magnetic field of the coil thereby producing reduced HT. For maximum HT you need an abrupt switching off of the voltage to the coil & a good condenser should provide this.

Share this post


Link to post
Share on other sites
  • 0
Posted (edited)

I checked inside the filter box. Absolutely not there. Maybe the ambulance variant is different. The wire to the distributor (off the coil) runs off the negative. Two wires are attached to the positive, both of which run back to behind the dash. One of theses wires is positive from the ignition, the other one doesn’t have any positive or negative and doesn’t appear to go anywhere, once it Trail’s back to the birds nest behind the dash. And their isn’t a ballast resister that’s I can see behind there. So I have no idea what’s going on. Should this random wire be connected to the ballast 

Edited by OZITIM

Share this post


Link to post
Share on other sites
  • 0

Please post some pictures of around the coil & of the inside of the filter box. It is very difficult to visualise your set up.

From the title of the thread & at the outset you asked for the location of the ballast resistor, by that I assumed you had a 24v system. But perhaps this is not the case & it is 12v, in that case I wouldn't expect there to be a ballast resistor.

Do you think all the wiring is original or maybe a previous owner has made modifications?

Share this post


Link to post
Share on other sites
  • 0

I had another search today, but could not find the ballast resister. I’ve replaced the points, condenser, and coil. I still have power to the points and will spark when I put the screw driver between the gap, with the ignition on. But once I turn the starter motor, no spark. I’m going to have to follow the two white wires that are on the positive terminal on the coil to behind the dash and try and work out what the hell is going on. Unless someone can give some sort of indication where the ballast resister is on an ambulance model. 

Share this post


Link to post
Share on other sites
  • 0

Oh, it’s a 12 volt system. I looked at the wiring diagram for 12 volt and it has a ballast resister 

Share this post


Link to post
Share on other sites
  • 0

Hello the ballast resister on my 12 volt 101 is on the near side of the engine bay adjacent to the coil and a pain to see/replace.

Regards Frank.

Share this post


Link to post
Share on other sites
  • 0

Thanks potless, would love to see a pic, if at all possible. I will play hide and seek with it again tomorrow and see if I can find it. 

Share this post


Link to post
Share on other sites
  • 0

Is it attached to the engine? 

Share this post


Link to post
Share on other sites
  • 0

Wherever the resistor is located it might be as well to do some preliminary checks as it may be quite ok..

The coil is a 16C6 & would have a resistance of about 1.5 ohms, the ballast resistor would have a similar resistance.

With the ignition on but not started, you should get 12v on the +ve terminal of the coil.

When you close the points this should drop to 6v. This would confirm that the ballast resistor is working.

It looks as if the ballast resistor is short circuited on running the starter motor.

Incidentally the ambulance UHB says that the basic electrical system is the same as fitted to the 12v GS.

Share this post


Link to post
Share on other sites
  • 0

These don’t really help. I think I found where the mounting holes were for the ballast next to where the coil was mounted, but there is no ballast there now. I was getting spark and it was running two weeks ago, but no spark when I kick over the starter. 

7BB69E9E-9F17-4B65-8B71-C03490A0F440.jpeg

CAA3C27A-A520-4AF9-BDEA-0ACD50564CFE.jpeg

07D5FB9F-2864-496E-859F-BDD178C49D0B.jpeg

C76E437D-4180-4A1A-9A9B-723253B4726A.jpeg

Share this post


Link to post
Share on other sites
  • 0

Below is where I think the ballast was originally mounted. By the look of the ignition, this ignition requires a ballast. So, either, their is a ballast relocated somewhere, or the ignition coil, despite it saying it requires a ballast, isn’t a ballast dependent coil, and the coil is no good. Thoughts? Can I just put a coil on it that doesn’t require a ballast and see what happens? 

A0DF6640-ED48-40B0-A064-F5505E476AE1.jpeg

B2760A2A-49B9-499E-B150-FDA8BD523959.jpeg

Share this post


Link to post
Share on other sites
  • 0

The coil may have been changed from 6v to 12v if the ballast resistor has been removed. The original clamp with its warning may have been loosened & a 12v coil slid in. A Lucas coil should have the part number & date code stamped on the base (flat bit), this will indicate if it is 6v or 12v coil.

Maybe the ballast resistor failed & a 12v coil fitted as a temporary fix or maybe someone thought they knew better than the designers & having a 6v coil + ballast resistor was a silly complication?

Wired with a 12v coil it will still run but the performance will not be so good at high revs because the extra inductance of a 12v coil over a 6v coil slows down the rate at which the coil can magnetise & demagnetise.

In other words loading the primary with more resistance & less inductance reduces the time constant of the circuit.

 

Share this post


Link to post
Share on other sites
  • 0

Running a 12volt coil in lieu of a 6 volt coil (with ballast) will make it harder to start.

When the starter is engaged the coil gets the full 12 volts so it has a fatter spark.

When you release the key it swaps to 6 volts supply to run the engine.

I think Clive is on the money with checking exactly what coil you have.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Answer this question...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...