Rectifier for a 1989 Sears riding mower.

[JerryK]

Your old motor probably had a sub 10 amp output, so if you put one in that is made to carry a larger current/dissipate the heat like the newer motors put out, you should be OK. A small motor repair shop can explain this to you and point you in the right direction. Your ' device ' probably only has one or two diodes in it, and no voltage regulation at all. That's what they used back then...

 

[PILOON]

Most Sears power products are made by MTD but each one has specific differences, enough that shops don't want to service.
Also sears want to sell you a complete assembly and not the component to repair.

PS I don't like to purchase Sears for that reason.

 

[check]

So, I went over to my friends place who has the mower, and we had a closer look. There are only two wires coming out from underneath the flywheel, and they are black and red. The third wire is apparently for a little light comes on when your battery is not charging. So, I'm going to get the three wire one that is shown on the Briggs and Stratton website. We are pretty sure that that will do the trick.

 

[JerryK]

Cool... LIFE IS GOOD....!!!!!

 

[check]

OK, so I ordered the part from Sears, and they also had a separate harness to deal with the third wire. Thanks, guys, will keep you posted!

BTW, I am impressed that I can still get parts from Sears for a 27 year-old engine!:thumbsup:

 

[check]

OK, new part arrived. What's wrong with this picture? Obviously the wrong part. (The smaller one in the foreground is the old part.)

Like, with two yellow wires, how do I know which one does he see in which windows DC? And is it true that, if I reversed them, I will burn out the new part?

Something is rotten in Denmark, even though the lady at Sears parts said that this was the right part for this B & S motor.

 

[Barry 1]

The 2 wires coming out from under the flywheel from the "Alternator" put out AC. Hook them up to the 2 Yellow wires.
When it is running,the red wire will put out DC+,and it should somehow go to the battery.

 

[JerryK]

No picture came thru.... The winding behind the flywheel ' usually ' is double ended, and if two wires are coming from under there, those are the two yellow wires. Inside the rectifier ' usually ' these two yellow wires go to two diodes. The two diodes are hooked together, and this connection has the third wire hooked to it... which is the output going to the battery. The two diodes only let the current flow in one direction, and you end up getting a pulse of voltage out of it thru each diode depending on which half of the coil underneath the flywheel is 'excited' by the magnet at that time. The voltage pulses flow thru the diodes to the center connection and out the third wire to give you the unregulated pulsing voltage that your tractor needs to operate and supply current to recharge the battery.... [ ??? ] [ this is actually uncomplicated... we used to have to put up with mechanical regulators and starter/generators... which were real finicky... ]

 

[check]

OK, new part arrived. What's wrong with this picture? Obviously the wrong part. (The smaller one in the foreground is the old part.) Like, with two yellow wires, how do I know which one does he see in which windows DC? And is it true that, if I reversed them, I will burn out the new part? Something is rotten in Denmark, even though the lady at Sears parts said that this was the right part for this B & S motor. dde22

Oops! Forgot to attach the picture.

 

[JerryK]

Yup, like Barry1 said whilst I was slowly typing out my long winded answer.... two yellow wires go to the coil. The output on the new one, the red wire, is the output. You have to decipher the wire colors on your old connector and splice in the new one.. using the old connector on the new part. Good Luck...!!!!