lauson/tecumseh h55 charging system

[1961551 2]

hi, everyone. the h55 is going together. my charging system is bad. im going to have my charging coils rewound if i cant find one soon. it is a 3 amp dual coil stator plate. i think a charging coil went out due to a faulty diode. one is bad. it takes two. does anyone know where i can find the replacement diodes for the 3 amp rectifier board system? i know its old and possibly obsolete. but im hard headed, and i dont give up. thanks to all. jimmy in n.c.

[oldandred 15]

check with the shack known as radio shack they have a replacement if you get the right person

[Save Old Iron 1,566]

Jimmy,

see if radio shack has the 6amp 50 volt diodes - the 6 amp rating will give you some level of overkill to help with unexpected current spikes from battery charging, etc.

http://www.radioshack.com/product/index.js...oductId=2062591

If the diode you removed from the stator has a "1Nxxxx" number on it - then it will give you an idea of the exact requirements for the replacement diode.

If you have a 3 amp charging system, I might suggest steering away from a 3 amp rated diode if you can.

[pfrederi 17,741]

I read the owners manual for a H-60 with the same charging system. It says that "If your battery shows signs of overcharging you should remove one of the 3 amp rectifiers (I assume that means diode). This will cut charging current approximately 50%. Overcharging may result from continued long operation of unit and is normal under such conditions."

I am not a electron guy but wouldn't using 6amp diodes result in a higher charge rate????

[formariz 11,987]

Jimmy

Most likely your system is not charging due to a faulty diode.If the system is run without the battery in place it burns out the diode.Star by eliminating that possibility before anything else.I have lots of the original type diodes .

I will send you a couple with the wiring diagram you requested.

[Save Old Iron 1,566]

Paul, good question.

A 3 amp vs 6 amp rating on the diode - think of it as a rating on a fuse. A 6 amp diode will PASS a greater amount of current before it overheats and self destructs. If your stator only supplies 3 amps - you will never overheat or overstress the 6 amp diode.

If your trying to charge a defective battery, you may max out the current drawn from the stator and the diode will give up long before the stator does. So in a way, the diode acts like a fuse. A very inconvenient fuse to replace.

My additional 2 cents here would be to place a fuse in the charging wire out to the battery - maybe a 3 amp fuse.

If you develop a short circuit in your output to the battery - let the fuse handle that.

Cas, is that the right rating on that fuse ? 1/2 amp and 400 volt

[formariz 11,987]

Hi Chuck

Yes that is the correct rating on the ones I have.I have used them for years without ever having one fail.The original ones with the 3 amp rating some how never lasted long.

Here is what the original one looks like

[Save Old Iron 1,566]

Thanks Cas,

I love this whole learnin' experience.

I have been in electronics since the 60's and I have to say I have never even seen a diode like this. Were they designed originally for some industrial or maybe a military application ?

[formariz 11,987]

I have found in the past references to this type of diode being used in military equipment. Seems to be a design used to facilitate quick replacement, almost like a fuse.

[Lane Ranger 10,970]

I found this information last year supplied by Ed Stoller and it has the most complete analysis of the 3 amp system used on the Tecumseh engines of any other soruce I have seen. I made two replacement rectifier boards using the techniques that Ed Stoller outlines in the attached article for my H60 Tecumseh engines used on my Lawn Rangers.

Here is the link so that you can see pictures:

Go to Section 5.12 with this link

http://home.earthlink.net/~edstoller/id11.html

If you have one of these old motors this guidance will work for you to restore it at really low cost.

Radio Shack as mentioned in this link on the Lauson H55 is a good source for some of the amps and other supplies. I used Mouser's :http://www.mouser.com/

and they have both online and printed catalogs. Reasonable prices also.

I tested mine after completing two boards and they tested out between 13.7 and 14.3 (Ed notes 14.7 volts output) and that is enough to recharge a battery and run a set of headlights.

********

3 Amp, One and Two Diode, Rectifier Created April 19, 2006, 3AmpRect.wpd

5-12-0 General,

Some of the older Tecumseh engines had a small stator under the flywheel and the Rectifier assembly on a board as shown in Figure 5-12-1,H 60A.jpg. Often the diodes fail and are no longer available, so this section is about how to replace the diodes with ones that are readily available, Figure 5-12-2, H60B.jpg. The circuit diagram is shown in Figure 5-12-3, H60Dia.jpg.

Figure 5-12-1

Figure 5-12-2

Figure 5-12-3

5-12-1 Replacement:

The original diodes were held in place with a fuse holder like clip that are riveted in place. I drilled the rivets out and replaced them with 4- 40 screws. The clip was replaced with a terminal lug shown in figure 5-12 -2. The replacement diodes are 1N5406 soldered to the new lugs. It is important have the banded end of the diode towards the fuse. Radio Shack has 3 Amp diodes; there 1N5402 has a 200 Volt rating which is a comfortable margin. If the original clips are held tight, one could solder the diodes directly to them.

Figure 5-12 - 2 Testing:

To test the complete system, disconnect the wire to the BAT + terminal and run the engine at about 3000 RPM. You should measure about 14 Volts DC at the BAT+ terminal. You can also measure the AC voltage across the two GEN terminals, about 30 Volts AC. To check the diodes, shut the engine down and disconnect the wires to the GEN terminals. Most newer multi meters have a diode test function. Using this to check the diodes, you should measure about .5 Volts in one direction and open in the other direction ( by reversing the red and black meter leads). If you don