Rectifier for a 1989 Sears riding mower.

[check]

OK, so if I hook up the two yellow wires and read the red one, it should show 12 volts or so of DC current? And it doesn't matter which yellow wire goes to which of the two wires coming out of the flywheel? If so, then the red wire on the new part hooks up to a wire somehow connected to both the red "discharge" warning light on the dash and of course the battery (in order to charge it). (Or maybe the red discharge warning light is on an independent circuit?)

 

[JerryK]

Yup, hook up the yellows [ either way ] then you should read a positive voltage on the red when she is running. The voltage could be anywhere between 12-16 volts or so not hooked up to the battery. Plus, it's not really solid DC, it is pulsed, but should be pulsing fast enough that most meters will read fairly correctly. Once you hook it up to the battery, the battery acts like a big capacitor and you probably would have to use an oscilloscope to see any fluctuation [ the actuall DC pulses ]. The new red wire should hook up to the same place the old rectifier output hooked to. You will have to trace it out.

 

[check]

Yup, hook up the yellows [ either way ] then you should read a positive voltage on the red when she is running. The voltage could be anywhere between 12-16 volts or so not hooked up to the battery. Plus, it's not really solid DC, it is pulsed, but should be pulsing fast enough that most meters will read fairly correctly. Once you hook it up to the battery, the battery acts like a big capacitor and you probably would have to use an oscilloscope to see any fluctuation [ the actuall DC pulses ]. The new red wire should hook up to the same place the old rectifier output hooked to. You will have to trace it out.

OK, thanks a bunch. Will be going up to the cottage this Friday, and can check it out over the weekend.

Thanks again, everybody. This has been very helpful. Long live TBN!

 

[check]

OK, thanks a bunch. Will be going up to the cottage this Friday, and can check it out over the weekend.

Thanks again, everybody. This has been very helpful. Long live TBN!

Quick update - it works! Thanks so much again, guys. My friend is so happy, as he could not find the relevant part anywhere up North, and he doesn't use a computer, nor the internet. So now he says I can borrow the mower any time I want, and even store it over at my place - nice! (Another reason why I won't be getting a mmm for my Kubota BX25.):cool2::thumbsup:

All's well that ends well, and let's hear it for TBN!

 

[JerryK]

 

[JRobyn]

Now that it's fixed, it doesn't really matter, but lately I've been having good luck getting all my small engine and lawnmower parts at Jack's Small Engine. Their parts diagrams are usually good.

That said, I just got a WRONG control cable for a TroyBilt mower, even though it is the one shown and the part number shown on the diagram for this exact model number mower. Spent 2 hours on the phone with MTD (manufacturer), who really couldn't help even though THEY were the ones who produced both the mower and the diagram. They could not explain why the cable I ordered was different, except to guess that maybe the cable and its attachment had been changed partway through the production run. They suggested a visit to the local MTD dealer for some sort of "adapter".

So the local dealer that MTD referred me to is out of business! Then I called another really good local repair shop I've used before. They said that MTD stamps the part number on their cable sheaths, so just get that off the old cable and order one of those. They were exactly right, and it turns out the part depiction and part number shown on the MTD parts diagram is WRONG. Jacks has the correct p/n cable in stock and is crediting me back for the wrong one. Only problem - cable I ordered 1st is $10, correct cable is $20. :mur:

 

[GLyford]

Yeah, I have noticed for some of the older gear that gaps are starting to appear in the manufacturers online part data, and it is getting less reliable. That's about the point where I start going back to basic principles and throw anything on the machine that works...but then, I am not after collector restorations either, just basic functionality.

 

[2458n]

MTD makes product for most of the big brands. They own what was at one time separate companies. Check the site for names that MTD now owns and you can see why finding parts can be a challenge. No reason for them to carry a ton of old inventory from a bunch of now defunct companies-they sell new stuff.

 

[buickanddeere]

As previously stated just about any old rectumfire and regulator can be used.
The voltage regulation does matter as some are just a zener diode and short over production to chassis, that style is not not recommended . A regulator that uses a solid state regulated supply and over current protection is recommended. Some systems combine the rectumfire and regulator into one unit.