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TR4/4A HELP not able to get my TR4 started

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Nice, thank you Art. Is there a special tool to take that notched ring off around the red light housing? Or do you just have to be clever.
 
There was a fellow selling the tool on eBay, but I don't have a link handy. I used needle-nose pliers for many years, then finally made my own.

But, there is no reason to remove it unless it's broken or you want to paint the dash or something; the bulb holder just pulls out of the back of the red plastic piece.

As you'll note in Dan's diagrams, the "ignition warning" red light is a special case, it is NOT grounded. One side of the bulb connects to the 'D' terminal at the control box (which should be hot when the engine is running); the other side connects to the ignition circuit (white wire) (hot when the key is on).

Also note that the bulb's resistance changes dramatically when it is 'lit', so you can expect to find that it has a much lower resistance than it's 2.2 watt power rating would indicate. But all you are really looking for is continuity through the bulb, it's exact resistance does not matter.

Book says 1/2" - 3/4" when pressing on the belt on the longest run (between crank & generator.
 
TR3driver said:
Also note that the bulb's resistance changes dramatically when it is 'lit', so you can expect to find that it has a much lower resistance than it's 2.2 watt power rating would indicate.
Click to expand...

Randall, would that explain why we use a 35 ohm resistor on our bench testers (we don't use a bulb) instead of say 65 ohms for a 2.2 watt bulb?? I never realized there was such a dramatic change in resistance when an incandescent bulb lights. Here I am thinking we're simulating a 4 watt bulb.
 
I don't think so, Art. I'd say the difference is due more to the difference between alternators and generators. A DC generator starts mostly on the residual magnetism left in the housing (hence the need to 'polarize' them, what you are really doing is magnetizing the housing & pole pieces) and doesn't need the light at all. But many (not all) alternators rely on the current through the bulb to 'tickle' them into life. The rotor doesn't retain enough magnetism to overcome the voltage drop through the diodes.

When I installed an old Ford Motorcraft alternator in my TR3A, I found that the bulb was too small for the alternator to start reliably, and added a resistor across the bulb. But it was less than 35 ohms, more like 10 as I recall. My Chevy also had a resistor across the bulb (so it's alternator would keep working even with the bulb burned out), that was around 10 ohms as I recall.

Likely your tester works OK with a higher resistance, because you spin the alternator faster during testing. The TR3A alternator would start with just the bulb, if you revved it to 6k rpm or so (at the alternator).
 
Actually, we slowly bring the alternators up to speed to record the "turn-on-speed" which is usually between 900-1500 rpm alternator speed. We set these parameters in the database for each alternator on a pass or fail. Of course, pulley size of the alternator is factored in. It's one of the tests the alternator must pass. We do not rev it high to get them going...quite the opposite. We monitor the voltage at the "light" circuit before we start spinning it, and after turn-on, simulating the light circuit. We do this so the operator doesn't have to monitor anything. Every test during the cycle is "pass" or "fail".

Curious thing about the lower resistance. We have an old tester that is used occasionally for Delco 10SI units, and that has an actual light circuit. To get the 10SIs to fire up, I did have to add a resistor across the light circuit to get them to activate, yet I don't have the problem on our regular testers with the 35 ohm resistor.

I'll take a look at the wiring diagrams of the testers tommorrow just in case I'm missing something.

Thanks for the input.
 
I'll see if I can dig out the shop manual for the Chevy. That's where I copied the resistance from. I just checked "The 12v Doctor's Alternator Book" and it says typical values are from 75 ohms to 300 ohms (with a 5 watt light).
 
I just got the battery back in the car. Before being hooked up, I was at 13.5 volts. After hooking it up and cranked it up, I was down to 12.8. Trying to do some further testing tonight.
 
Art, I found the Chevy manual, and it does say 10 ohms. But it also says that it is needed to protect the diode trio, so I'm not sure what to make of that. My car had a 15SI but the wiring was the same as the 10SI.
 
Trying to make some sense of the Lucas Test PDF you sent. In step 1 it says to "Disconnect leads from generator." I assume those to be the two leads on the generator, then take the DMM and attach one lead to the D terminal and one to ground. Where is the D terminal on the generator? I know there is a D terminal on the regulator, is that what it's referring to?
 
Right, two wires to the generator. The D terminal on the generator is the larger one (which is also linked to the D terminal on the regulator). The F terminal is the smaller (likewise linked to the F terminal on the regulator).

For test 1, voltmeter from D terminal on generator to ground (generator case).

For test 2, link F to D at the generator, voltmeter from either one to ground.

These two tests basically verify the generator, without the regulator in the circuit (so no question about where the fault lies). If either test fails, stop and repair the generator; then retest until it passes both tests.

For tests 3 and 4, the two wires get reconnected at the generator, and disconnected at the regulator (these tests basically just verify that the wires are good).

Then follow part 2, starting on page 5 of the booklet (this is the section that applies to the TR2-4 regulator).
 
BTW, I have a better scan of that booklet, which is small enough to email. It's on the web somewhere (but I forget where offhand). If you (or anyone) would like a copy, PM me your email address & I'll shoot it right over.
 
Randall,
Just tried to send you a PM, but you seem to be over your limit. The burden of being popular.

Thanks for clearing that up, I'll do the testing when I get home.

So I realized last night, the Voltage Regulator on my 64 TR4 seems to be from a TR3. Has only 5 terminals instead of 6, and they are screw on. This sucks because my repair manual is for a TR4 with the different Regulator. I'm wondering if that is why the red light never comes on, it may just not be wired. Was the TR3 VR in the TR4 a common thing or someone back in the day just made it work?
 
The TR3 and TR4 regulator are functionally interchangeable (actually, the switch was during the TR3A run). With the screw-terminal version, there are just two wires under the 'D' screw; one for the generator armature and one for the warning lamp on the dash.

Not a common replacement AFAIK, but nothing wrong with the swap. No doubt someone needed to replace the regulator and the screw-terminal version was available.

PM situation should be cleared up now. I thought I had deleted all those old messages, but guess I was mistaken.
 
Ok, just got Test 1 complete, Randall et. al. if you could verify my logic in understanding the tests and my findings it would be much appreciated.

connected negative of MultiMeter to D terminal on the generator and postitive lead of MM to ground.
At idle I was getting 1.3 volts. As the engine speed went up towards 3K rpm, the voltage increased to 2.5 volts @ 3K rpm. My understanding is this is Reading C on test 1, Rising volts with rising speeds - thus internal short between D and F terminals, examine field coils and replace if necessary. Anyone concur with these findings?

I understood reading A to be 2-4 volts from idle up to 3K rpm, correct?
 
Is this electronics 100.
If not I'm in the wrong class.
 
Doug, I believe your results fall within case 'A'. I believe it should be read as "The voltage should be within the range 2-4 volts when the generator rpm is 3000 rpm."

In any case I am reasonably sure that your results do not fall within case B (open brush or armature); or within case C (field-armature short). For a field-armature short, the voltage would be above normal charging voltage (eg 20 volts), not just 2.5.

I would proceed to test 2. I hadn't realized it wasn't in this book, but the workshop manual warns not to let the generator voltage exceed 20 volts during test 2, as higher voltage may damage the insulation (ruining an otherwise working generator). That's part of the reason these things are so fragile, they will happily turn out enough voltage and/or current to kill themselves, without the regulator to keep them under control.
 
DNK said:
Is this electronics 100.
If not I'm in the wrong class.
Click to expand...
Don, this is closer to the "electric shop" class I had in high school. No electronics involved, just relatively simple electro-magnetics. (Which was a disappointment to me at the time, I could have taught that class!)

Should we start with making an electromagnet from a nail & some wire? :laugh:
https://www.iit.edu/~smile/ph9528.html
 
Must have missed that class when I took Home EC :laugh:
 
Prezactly, Frank!! It'll work in th' bottom of a bucket of err....
well, it'll just WORK, even if it's only HALF right. :laugh: :thumbsup:
 
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