Few Electrical Questions - Workbull

Howdy Gents & Happy Labor Day Weekend

I somewhat tore apart a MF 202 Workbull and I have some wiring questions now that I'm putting it back together. I'm pasting a before and after/proposed diagram. The way this was wired has me scratching my head, and I lost some of my tape on the wires telling me where they go, so in the diagram anything marked 'unk' means unknown.

My questions will focus around my proposed diagram, please let me know if you see any issues I'm not asking about as well. And thanks in advance!!

1. Is the ammeter I bought 'strong' enough to be wired between the battery and alternator? This is what I have:
http://www.ebay.com/itm/Ammeter-Amp-Gauge-fits-Massey-Harris-81-82-201-202-203-333-404-444-555-303-I-24/232259520208?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649


2. Given that I have an ignition switch with a 'start' post, do I really need to use the starter button or could I skip that? My assumption is that they do the same thing and that either one or the other is needed (but not both).

3. Neutral Safety Switch - Assume this connects inline between the start switch (whether using the start from the ignition switch or starter button) and the start post on the solenoid. (I have a 4 post + ground solenoid)

4. Assume I don't need to use the 'i' post on the solenoid?

5. Not 100% sure where to connect the #1 wire from the alternator. Can I hook this to the acc on the starter?
<image src="http://forums.yesterdaystractors.com/photos/mvphoto2914.jpg"/>

1. I?ve used 30-0-30 gauges with alternator and got along ok as long as battery stays charged up

2. Try it, it should work

3. Yes, Neutral safety switch goes between start activating switch and S on start solenoid

4. You could use a 6 volt coil, or 12 volt ?external resistor required?, and add a resistor between coil +and ignition switch. Then run wire from I on solenoid to the resistor side of the coil. Resistor will drop 12 volts to 6 to operate 6 volt coil, but when starter cranks the engine, solenoid will activate the I post and send 12 volts to the coil, bypassing the resistor, for hotter starting spark.

5. #1 on alternator can go to ACC on switch, or through a diode, resistor, or indicator light to the coil side of ignition switch.

Alternator output should go to one side of ammeter, and other side of ammeter to battery connection at start solenoid.

Ignition and light switches should power from alternator side of the ammeter

Instrument lights should power from a light switch

With engine not running and lights and/or ignition on, ammeter should swing slightly to negative. If it goes positive reverse ammeter connections.

Thanks RVirgil, really appreciate the help! Everything seems to be working, which is always a plus.

On the coil, after too much reading, I'm going to leave as 12v but add a .6 ohm resistor to compensate for the higher voltage from the alternator (14 vs 12 volt).

What I've yet to figure out is why a true 12v coil doesn't incorporate extra resistance (~.5ohm) to compensate for the higher alternator voltage. My guess is maybe due to starting on a weaker battery. I'm sure there is some logical reason.

Thanks again and happy labor day

Glad to help. With added resistance don't be surprised if you have a harder starting problem.

The original generator probably charged at least in the upper 13 volt range. I have 3 tractors with alternators, direct 12 volt coils, and no added resistor. I've had no problems with alternator charge level.

Direct 12 volt (no external resistor required) coils are designed to run off of a well charged battery with no resistor. If you do have problems, I would be checking out the alternator regulator.

6 and 12 volt are basic designations. Both operate above that level.

Well, maybe I'll leave as-is and see what happens. With this exercise i have found out that on my 8N I'm using a resistor that seems to measure .8ohm on a 12v coil (maybe this is the .6 resistor and due to temp it shows .8, probably 90 degress, not sure). The 6v coil set up seems to make a lot of sense, if bypassing the resistor for starting. It was a post from soundguy that discussed 12v being better if run with a .6 ohm resistor. My 8N made it about 350 hours or so before I burned up the points, but that was probably due to me not adjusting the point gap periodically, it was practically 0 when I checked, surprised it even ran.

Since you're on such a roll, let me ask you one more question if I may... Back to the workbull I've been putting back together. When reading volts on the alternator and battery, its so erratic that I cannot get a reading. So I'm trying to figure out how to test the alternator's voltage regulator and I just can't quite figure it out. From what I see online, I should stick something into the D opening. I'm not sure which opening is the D, none stand out as correct, they all just seem like cooling holes. In the attached image I'm taking a guess. I did remove both the #1 & #2 terminal wires and still got the same unreadable readings.

To make it short, what hole would I insert a screwdriver? Picture attached.

Also, I saw something about connecting tabs A & F. I assume F is the field, same as #1. Not sure what the 'A' tab is. Or if this is even a good idea. I also saw something about connecting all 3 posts to the battery, but I'm hesitant as I'm afraid I may fry something (like myself).

Or if you think something else may be affecting the volt readings, I'm all ears. I'm also going to replace plugs and wires, as the last person had 12v going to a 6v coil.



Thanks again!!


<image src="http://forums.yesterdaystractors.com/photos/mvphoto3067.jpg"/>

Does your 8N have a front mount or side mount distributor. Front mount uses a special resistor, side mount does not.

If you are using a digital volt meter the erratic readings are normal. Generator and ignition hash can interfere with digital pulses in the meter and cause it to go crazy. You will need an analog meter to read these voltages.

Grounding the D opening is only a go/no go test, won?t tell you much about the regulator. All that does is force it to full charge. Best way to check alternator is to get analog meter and check battery voltage with engine running or take alternator to an auto parts place and have them check it.

Are they A and F or R and F. R and F were common on older Delco with external regulator and some of the early internal regulated.

Voltage to #1 pin on alternator excites it to begin charging when first started up. Then Trio diodes in alternator feed power to regulator. If you unhook this pin before starting engine it probably will not start chraging. It should be connected to coil side of ignition switch. Do not connect it to battery and make it hot when engine is off. The #1 should also have an isolating diode, resistor, or indicator light or the line may back feed the switch and the engine will keep running when switch is turned off.

#2 pin is reference voltage and tells regulator the battery charge level. This pin is often connected to battery charge output wire.

Thanks again!

The 8N is a side mount. I rebuilt this one a couple years ago, obviously my memory isn't the best cause I had to start my electric learning curve all over again! I'm assuming someone gave me the advice to add the resistor when I went through that process. The logic of the small resistor is that the coil is meant to operator at 12v but the battery charges at 14v. Maybe bad logic, dunno. But seems to work just fine, although maybe plug life would improve without the resistor (less fouling perhaps).

I was using a digital meter. I hooked it up to an analog voltmeter and it was not jumpy. Now just need a better analog to see what the actual reading is (mine goes to 300 v so tough to tell exactly what its outputting). I had hooked the digital gauge up to the 8N just to make sure it was working correctly and it actually read that without being jumpy. I guess less 'hash' on that old gal vs. the workbull.

On the A,F,R thing... Mine is marked 1 & 2, although there is another hole labeled 'R', that apparently is for a tach (read that somewhere). Either way, no big deal at this point as it appears to be a digital multimeter issue vs. alternator issue.

I have the #1 hooked to the ACC on the ignition switch. And realistically the ignition is never put in the ACC position, so I'm not worried about it being energized without the engine running. Figure this way I don't have to put a diode etc in the wire as if I had it hooked to the on/ign terminal of the switch (which feeds coil).


Thanks again for the help. Hopefully with a little more tinkering she'll be rocking and rollin.