Not charging; Control box

[Dave Herrod]

For the last few weeks, my car hasn't been charging and I finally set to to find out what was what.

 

I discovered that if I manually held the contacts in the control box closed the ignition light would go out and the ammeter would show a charge. However, the contacts wouldn't stay closed.

 

I replaced the control box with a new (copy)one only to find the same thing, but with the exception that if I manually close the contacts they remain closed and the ammeter continues to show a charge. Having done this, I set off to work this morning but half way to work, the ammeter started showing a discharge (which increased with using the brake lights and electric fan) but the ignition warning light didn't come on.

 

I stopped and restarted the engine when I got here and, as before, the charging light stays on. Haven't tried anything else yet, but would appreciate any ideas.

 

Dave

[Dave Herrod]

This one obviously hasn't struck a chord with anyone.

 

As a follow up to my last post, I tried to manually close the relay contacts, but they wouldn't stay closed. Could a problem with the wiring somehow result in too little current flowing through the coil to keep the contacts closed? Does anyone know of a link to a description of how the control box works so that I can work out what might be going wrong?

 

Any comments gratefully received

 

Dave

[jonlar]

Hi Dave, as there's been no other takers and a new control box hasn't sorted the problem, I'd be wondering about connections, or possibly/probably a broken wire.

[RogerH]

Hi Dave,

It's not always a good idea to poke your fingers into coils and close them manually, they could have an interesting but dodgy effect. Halfords do a very good book on auto electrics from the very basics to the very modern - TR's are in the basic area. This explains what all the coils are doing and why and how to test them. It really is quite simple but you do need to have the info in front of you.

 

Best of luck

 

Roger

[BrianC]

Dave,

The TR2/3 Service Instruction Manual (factory workshop manual) has a good description and diagnostic/set-up details which enabled even me to sort out an errant control box many years ago. If you have bought a repro box, there is no guarantee it's been set-up and tested correctly. It might be worth trying a known good one from another owner before getting too technical. If you haven't already got the workshop manual, it's worth getting the CD-ROM which also includes the parts manual and drivers handbook, and works out a lot cheaper then the Brooklands reprint.

[Rhodri]

Are you really sure the dynamo is giving out a charge? You can check it by disconnecting the wires from the dynamo, joining the two terminals together and connecting them, through an old headlight bulb, to an earth on the car. Start the car and gently rev it to just above idle. The more you rev it , the brighter the light. Don't rev it too much, nor for too long. This will check the output from the dynamo, and, if you have a voltmeter, you could use that in place of the bulb and expect 14 or so volts.

[tr3timme]

Hi, Dave: in my experience you have to be very careful indeed when closing the control box points manually. If it is done at idling revs, then there is a likelihood that the dynamo wiring will be burned out. Worst case scenario, reading what you have tried (and again according to my bitter experience) could be that while you have replaced what might well have been a faulty box, it 's too late anyway since although you have this new part, the dynamo is lunched and therefore similar symptoms are manifesting themselves. Worth testing the dynamo itself now, to see if it's OK.

At least neither item is particularly expensive!

Good luck, Tim.

[Dave Herrod]

Thanks everyone for your responses.

 

I certainly did have an output from the dynamo but, after reading Tim's post I will need to check if I still have! I will have another go this weekend and let you know how I get on. Fortunately we now have enough daylight for me to get home without needing the lights!

 

Dave

[Don Elliott]

About 3 years ago, I bought a new control box as a spare, just in case my original one gives me trouble some day. It's been on the car 49 years now. I bought my new from Roadster Factory in USA and it came in a green box marked LUCAS with all the normal Lucas markings. Is this a repro ? I haven't tested it but I plan to test it later this summer. It has paint marks on the screws and the tech person at TRF told me it has been pre-tested and pre-set. All I have to do is put it in. No adjustment needed. If fact, he added, if I tamper with the settings, it voids the guarantee and they won't take it back. If I find it doesn't work, I should send it back for a full refund or another replacement free, providing I haven't broken any of the painted seals on the adjusting screws.

[jonlar]

Hi Don, the green and white box indicates more recent manufacture, the 70s and some of the 80s had red and white boxes, there will almost certainly be a week and year number somewhere on the Control Box itself, usually a 4 digit code - they should be set up and ready to go. In the 60s and 70s, Lucas used to doe exchange items for dynamos etc., labelled Lucas B90 exchange.

[Richardtr3a]

I have had nothing but problems from this area and have six useless control boxes in stock. The last was a green box Lucas which stuck open and burnt out the dynamo. I replaced both and a new battery and it is all working well now. However the replacement control box was a Lucas B90 unit and is well set up and the rivets are properly made so that there is a proper contact and the connections do not fall off. I am upset that the green box Lucas cost £40.00 and lasted 3 months. My B90 is dated 1977 and was found as new old stock.

Can anyone recommend a Lucas agent, or electrical specialist who can repair, overhaul and set up my stock of broken control boxes?

I still have brake problems on the Girling back axle.

[Dave Herrod]

Finally got around to investigating further.

 

This time, I had no output from the dynamo; it transpired that one of the brushes had finally given up. I suspect that output had been low/intermittent and insufficient to pull in the regulator contacts. All now charging OK apart from the fact that the new control box appears to be allowing a charging current of about 20A which I never saw with the old box. (Having written that, is it possible? what is the max capacity of the dynamo?) I am a little concerned at this and will probably put the old box back in as I suspect it wasn't faulty after all.

 

D

[stuart]

Finally got around to investigating further.

 

This time, I had no output from the dynamo; it transpired that one of the brushes had finally given up. I suspect that output had been low/intermittent and insufficient to pull in the regulator contacts. All now charging OK apart from the fact that the new control box appears to be allowing a charging current of about 20A which I never saw with the old box. (Having written that, is it possible? what is the max capacity of the dynamo?) I am a little concerned at this and will probably put the old box back in as I suspect it wasn't faulty after all.

 

D

Dave if your battery is still down after all the problems you have had its just the dynamo trying to bring it back up, if not then you could adjust the control box as per the manual. Does it show a little discharge at low RPM with headlamps, wipers and blower motor on?This is normal but if it is still showing a healthy charge then thats a bit too much and it may start to boil the battery.

Stuart