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MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG TD TF 1500 - 34 Amp Generator

Or, dynamo, if you insist. A little bit ago I opened a thread Tachometer Gearbox Issues about how my tachometer gearbox greased up my generator commutator. Well, since I've reassembled the cleaned up armature and brushes, I now have a generator that loves the high end of my 30 amp ammeter. My voltage regulator/control box is a refurbished 5 terminal unit that I obtained from Jerry Felper about a year or so ago. Driving at 2500 rpm it's putting out over 20 amps. I have to assume that it's going into the battery. There's slight indication of boiling around the edge of the multi-cell cap. The battery voltage after sitting for a bit is a healthy 12.6 volts. See http://www.ttalk.info/34Amps.MOV for a video of under-the-bonnet view. I've tried a second voltage regulator with the same results. Driving with the headlights on lowers the ammeter reading, but it's still too high. Any ideas? Besides regreasing the commutator? Bud
Bud Krueger

The Workshop Manual has a long section on setting the voltage regulator.
Dave H
Dave Hill

Dave, it's unfortunately designed for use with 9 pin regulators. I've tried its techniques with no luck. Bud
Bud Krueger

Bud,

On our cars, the current is not adjustable, it depends on the state of the battery, if the battery is discharged (low internal resistance) it will draw a high current, once charged it will draw less current (high internal resistance). However 30 amps seems a lot for these generators, the rated output for a C39PV2 unit is 19 amps. As the next test, you could try changing the battery. If that fails below is a link to the Lucas document giving full test information for their generators and control boxes. I have used it in the past, it is useful.

https://britishcarbreakfastclubcom.files.wordpress.com/2015/11/lucas_generator_and_control_box_tests.pdf


John
J Scragg

Or put the battery on charge overnight and see if the result is the same.
Ian Bowers

I have been anticipating that the current would drop down as the battery charged. However, the battery voltage at start is about 12.6 volts, indicative of a full charge. I've hooked it up to a 10 amp charger overnight before taking it out. Same effect. The battery is only about 2 years old.
I have a copy of the Lucas Generator and Control Box Tests manual. I'm going to pour through it to see if there might be something in the 'Action' procedures that might help. Bud
Bud Krueger

Bud

12,6V is good for a battery without charging.If you read 20Amps - what is the voltage?
W_Mueller

Bud, can you rig up a volt meter to monitor your generator output? I got one that fits an accessory (cigarette lighter) socket and reverse wired it for positive ground. My generator puts out 16.5 volts (way to high) at 3K rpm. My battery is pretty good and my voltage regulator has been overhauled by one of the recommended guys. After start-up I read pretty close to 30 amps and 16.5 volts at 3K rpm but that soon settles down to slightly positive amperage and about 14.5 - 15 volts at cruise (3.5K rpm) speed.

I don't know if this helps but I've been living with it for 2-3 years.

Jud
J. K. Chapin

Sonuvagun, it looks as if I may have found the symptoms listed in a document that I had forgotten about. Jim B. reminded me about the booklet 'Lucas Generator and Control Box Tests'. I started in on Part 1, TEST 1. My readings matched those called 'Rising volts with rising speed'. Indeed my voltage readings were almost exactly 1/1000 of the engine rpm. This calls for an action of "Internal short between D and F terminals, examine field coils and rectify as necessary or fit replacement."

To pin it down I need a resistance reading from one of you good folks who may happen to have a generator handy. What is the resistance that you measure from the D terminal to ground (the case) with the wire removed from the D terminal?

You may get a variety of readings because you're reading across commutator segments. Thanks.

Thanks a lot Jim B.

Bud

Bud Krueger

Bud,

It sounds as if you have a problem in the wiring of the field coils, the most common cause is that the wire connecting the two field coils is shorting to ground through one of the long body bolts. This wire should have a insulating sheet folded around it. If that's not the problem, check that you don't have a short somewhere in the complete circuit from the F terminal through each field coil then to ground.

John

J Scragg

Thanks for the response, John. That particular problem I've run into before. In 2005 I obtained a solid state regulator from the late Bob Jeffers. It just wasn't working right. Bob had me measure the resistance from the field terminal to ground. It was 3.1 ohms. He said that's the classic value for a shorted field coil. One should read 6.2 ohms for the two of them in series. I'm reading 6.2 ohms. I have the body bolts encased in shrink tubing. I wish I new the resistance of an armature coil. Thanks again. Bud
Bud Krueger

Is this of any use Bud? http://www.mossmotoring.com/pint-size-project-the-generator/ Cheers
Peter TD 5801
P Hehir

Thank you, Peter. It doesn't help me find a solution, but it answers my question about the resistance of the armature coils. The answer is - about 1 ohm. Hard to troubleshoot a short versus 1 ohm. Now the 'internal short between D and F terminals' doesn't make sense. I'll reassemble it and do some more analyzing. Bud
Bud Krueger

Yecchh!! I can't find it. I've tried 3 Control Boxes with no luck. I must admit that the problem is somewhere in the generator. It has a serious case of positive feedback. Must admit that the field coil wrappings do have that Egyptian mummy look that someone suggested. It's a C39PV2 that celebrated its 60th birthday last month. I installed a Holcombe armature in 2005.

I've decided that it's perfect motivation to bite the bullet and give the Dynamator a shot. I ordered one from Abingdon Spares Saturday morning. Installation will be a learning experience and I'll start putting together a web page for Ttalk. I did an archive check and was surprised at how many threads there are from folks who have already installed alternators. Bud
Bud Krueger

Eureka!! The Dynamator from Abingdon Spares arrived in Friday's mail. As of this afternoon I have successfully installed the Dynamator in two configurations, one is as a stealth mode using a modified control box (Voltage Regulator). The other is with the control box replaced by a common 8 position terminal strip. The only wires that I replaced are the two connecting directly to the Dynamator. The Dynamator uses push-on connectors rather than ring terminals. I wanted to have a 10 gauge wire connected from the D terminal to the car's wiring.
The only 'uh oh' showed up when the generator fan was clipping the screws on the front of the Dynamator. Adding a .018" spacing washer ended the problem. I'm now suspecting that it's the repro fan that is the culprit.

This Dynamator is for a negative ground configuration. There are only two places where wiring must be changed. The wires presently connected to terminals A1 and A of the control box must be connected together, and the wire from terminal D must be connected to these two wires. The other change is to remove the small yellow wire from the D terminal and connect it to the yellow/green wire now on the F terminal. This can all be done on a control box that has been gutted!

Tomorrow I'll get started on writing up a web page for Ttalk showing how I've done this. I'm amazed at how simple it was. Here's a photo of the underside of the control box. The yellow wires are connected to a 40 amp fuse folder that goes under the control box cover. mY next entry will show the terminal strip version. Bud



Bud Krueger

Here's a shot of the 8 terminal connector strip that I wired up to instead of the control box. $13 got me a pack of 4 of them with jumpers from Amazon. The 40 amp fuse holder was from NAPA at $3.41. Bud


Bud Krueger

Bud, you wrote "This Dynamator is for a negative ground configuration. There are only two places where wiring must be changed."

Does this mean that you converted from Pos ground to neg ground? If so, don't forget (and I know you wouldn't) that if you have any accessory outlets reverse wired or any polarity specific LEDs they also have to be changed.

I don't have any LEDs in my TD but I do have two accessory outlets that I would probably have forgotten to unreverse and then fried my Garmin and my little plug-in voltmeter.


Oops, and I would also have forgotten to unreversed the accessory outlets on the dash and then fried my electrically heated driving gloves.

Jud



J. K. Chapin

Sorry about that, Jud. Guess I should have been more specific and said that I was speaking of a car that had already been converted to a negative ground configuration. Being an old electronic'er, Lazarus has been a negative ground car since he adopted me 30+ years ago.

Were those your Harley gloves? Bud
Bud Krueger

Them's the gloves. Can't drive in January or early February without them. Love'm. These are my old non-electric gloves. My fingers nearly froze off with them. Jud

ps: Sorry to have started this tangent. Maybe it would be interesting to have a thread showing other driver's winter gear.


J. K. Chapin

35A from the generator will melt the solder attaching the rotor windings to the comultator.

Jan T
J Targosz

Might have do so, Jan. It's given up the ghost and passed the buck to a Dynamator. http://www.ttalk.info/Dynamator-for-Lazarus.html (under construction) Bud
Bud Krueger

Latest - http://www.ttalk.info/Dynamator.html Be sure to refresh your browser. Bud
Bud Krueger

The dynamo for the Bug Eye Sprite also has a rear plate to take a tach drive. What is the output of this later unit? I think I temporarily ran one on my TD many decades ago.
John Quilter (TD8986)

Hi Bud,

I have fitted a Dynamator to the TF and as yet it has worked perfectly. The only issue has been with the large, knurled nut on the tacho gear box. This bottomed out before everything was tight and I have had to fit a washer to stop any slop. I suspect this was due to a damaged thread in the nut though since no one else has reported this as a problem. I ran a heavy duty wire directly from the alternator to the battery and by passed the ammeter for charging but retained it for feeding the circuits in the car. I rely on the warning lamp to show everything is working. Again I don't think this is necessary since no one else has reported a burnt out amp gauge. I did remove the spade connector and replaced it with a screw terminal. This has probably invalidated my guarantee but I have carefully stored all the parts I removed. The terminal is in the case though rather than the end plate but does look better than a spade connector.

Jan
J Targosz

Jan, you're not alone. When I tried to attach my tachometer gearbox to the Dynamator I ran into the same issue. The coupling nut would only go about half way on. I dug into my tacho gearbox goody box and pulled out another coupling nut -- same effect. I dug out another coupling nut, and this one went on as sweet as could be. But -- it is a brass one. The two problem nuts are white metal. I've brought this to the attention of Ed at Abingdon Spares and asked him to check on it.
FYI, I have the later 30-0-30 ammeter in Lazarus. Bud
Bud Krueger

When I first installed ours, the gear reduction shaft would not insert into the alternator stub shaft and a nut would nut screw on the end anyway.

After replacing the bracket and stub shaft, the nut bottomed out and the gear drive was flopping around loose, like yours, Jan. I stuck a small o-ring into the nut and the drive sets snug now.
JIM N

I didn't have any of those problems, but I bought mine less than a year after they became available in the UK (maybe 4 years ago) so maybe things have slipped since then. I imagine this product is of Oriental origin with the internal components coming from a standard low output mainstream alternator with a custom made casing for our application. Whatever it is, they seem to be reliable and remain relatively inexpensive compared to some / all of the alternatives. I still have the std ammeter in circuit with upgraded wiring, but I also have a Voltage sensing LED mounted inconspicuously on the bottom edge of the dash, which properly confirms all is well with charging.
Dave H
Dave Hill

Hi Dave,

I don't think the dynamator uses proprietary "insides". I bought a very expensive dynamo lookalike alternator from Moss about four years ago. Despite the £500 price tag it failed four times. Moss were excellent and sent me replacements at no cost each time. Eventually we both decided to call it quits and they immediately refunded all my costs. However I did take one of the failed alternators to a very reputable firm of auto electrical engineers in Glasgow for their comment. They were able to look inside the unit with an endoscope and identified the workings to be from an alternator fitted to a ride on lawn mower. This normally had a casing littered with cooling slots but when housed in a dynamo case these were missing and when under load the converted alternator was overheating and burning out its diodes. I have not heard a single complaint about the dynamator so they are either using a custom alternator or have solved the overheating problem.

Jan
J Targosz

Jan. Yes I remember all your problems with the type that you bought first time around. You may be right, but seems to me the cheapest route would be to use parts that were sold by the million rather than made in small numbers for our cars. Most modern cars have much bigger alternators, owing to all the electrical kit cars have these days. However this may be less true in say India or China. I don't know how they fixed the cooling problem, though there was some kind of description on here fairly recently of how these particular alternators work that seemed to go part of the way there for me. Something to do with a reduced electrical cycle.
Dave H
Dave Hill

Weather finally allowed me to take Lazarus out for a run with the Dynamator under the bonnet. It's wired in with the 8-pin terminal strip. I have a digital voltmeter display plugged into the cigarette lighter outlet that I use for my USB plug. Was easy to monitor output voltage while viewing the ammeter. Below about 1100 rpm the voltage level was below the battery voltage and the ammeter was just about at zero. By 1200 rpm the voltage jumped up to a bit over 13 volts and the ammeter was showing charge. By the time I got up above 1500 rpm the output voltage was happily running around 14.3 volts while the current dropped down into the 3-4 amp range. Such a relief to see the sort of numbers that the system is supposed to present. Bud
Bud Krueger

Bud, can you tell me about your digital volt meter? I have one but it cycles through voltage, temperature and amps being drawn through the USB port. Two out of three displays I don't need. I'd love to find one that just continually read volts.

Thanks.

Jud
J. K. Chapin

I fitted a conventional dial Voltmeter on the bottom edge of the dash for the first few months so that I could get the same kind of assurance of output. After a while, confidence gained, it became obtrusive and out of place - these Dynamators are reliable.
Dave H
Dave Hill

Jud, I bought one of those for my daughter to monitor her 1990 Dodge pickup. One beef with it was the temperature was in Celsius. This one just shows voltage and has three leds indicating low(red), Okay(yellow), high(green). I'll check the specs after coffee. Bud
Bud Krueger

I bought an LED in UK that is voltage sensitive, redcwhen too low, Amber when low and green when good.

Have not fitted it but tested, works well.

Peter
P G Gilvarry

Jud, it's the Equus Innova 3721 Battery and Charging System Monitor. Walmart has it for $17.29. Bud


Bud Krueger

Thanks. I'll be going to W-mart this afternoon anyway.

Jud
J. K. Chapin

The voltage sensitive LED works really well and is ideal as its so unobtrusive mounted on the bottom edge of the dash, so barely noticeable when parked.
Dave H
Dave Hill

Dave, can you give a bit more detail on that LED. I can't seem to be asking the right Google questions to look its source. TIA, Bud
Bud Krueger

The supplier is Gammatronix. You will find them on gammatronixltd.com or on ebay uk.
Dave H
Dave Hill

FWIW
I have a USB port with a digital voltmeter display. From Amazon. I removed the rain cover and mounted it on a small bracket just below the dash. The bracket is a separate item made for the port.


Mort Resnicoff

This thread was discussed between 05/02/2019 and 28/02/2019

MG TD TF 1500 index

This thread is from the archive. The Live MG TD TF 1500 BBS is active now.