Rectifier board for Craftsman generator

[Joe Stewart]

Hello generator experts. I'm trying to repair a 2400 watt Craftsman generator, model #580.328330. Serial #030228. You can look at my previous post for photos of the whole machine. A reputable source advised me to replace the "board, bridge rectifier" sears part #66850. I took the old one out and attached a couple of photos of it. The old one looks ok to me but I understand that it still could be defective without any obvious external signs. This rectifier board gets very hot while the generator is running. Anyway Sears wants $48.50 plus shipping and tax for this part and I'm not sure that the whole generator is worth this amount. Someone told me to buy it elsewhere since it would be a lot cheaper, but I'm having trouble finding a source for this part. I believe that Generac built the generator section for Sears, although there is no manufacturers plate on it. My question is: Where can I buy this rectifier, besides Sears? I'll try Generac this afternoon but I am wondering if they will be able to work with a Sears part #. Thanks for any input! Joe Stewart

[Jim Rankin]

Test the rectifier board with an ohmeter. Check each diode on it and make sure it conducts in one direction, but not both. resistance in the direction it conducts is usually 600 ohms or there abouts. resistance in the opposite direction is infinite.

The board should build up some heat, it is probably in the airflow through the generator end to keep it cool, and many times they are attached to finned aluminum heat sinks. Another alternative is that there is a shorted winding and the rectifier board is handling short circuit current and getting hot as a result.

Try your picture again with less resolution. Some cameras have an email or web setting that is something like 640x480.

[Joe Stewart]

Thanks for the reply, Jim. I'm not sure which are the diodes or even if this thing has any. I've tried to attach the photos again so you can see what this thing looks like. I went to the local Generac place and to two electronics suppliers and they told me that they cannot get a replacement. So I guess this is a Sears item only, unless anyone else has any ideas. Thanks. Joe Stewart

[Joe Stewart]

Here's one more photo.

[Kevin K]

The board looks like it is custom made for Sears, and you probably cannot find one anywhere except Sears.

From the picture, it looks like a standard bridge rectifier containing four diodes (the black rectangular item), a MOV (the blue item), and a resistor soldered to the board. If you can solder, you can replace the components for a few dollars. The MOV will conduct when it's voltage threshold has been exceeded, probably on the order of 250 volts. Unsolder it and measure the resistance, it should be open. The bridge rectifier can be replaced for a couple of dollars. For example, GBU610DI, 1000volts, 6 amp, available from DigiKey (www.digikey.com). You can probably find a similar device at Radioshack. The 1000 volt 6 Amp is overkill, but it will be safe. Make sure the replacment is the same physical size. Be carefull when replacing the bridge rectifier, it is polarity sensitive. One end is marked + and the other end -. Make sure you mark the board when you remove it so it can be replaced correctly.

[Joe Stewart]

Thanks for the reply! It looks like all the solders for this board are buried in hardened resin in the base of the black plastic tray. Do I have to break out this resin and then replace it somehow when I'm done replacing the components? Joe Stewart

[EricWood]

That's too bad. Couldn't tell for sure from the picture, but thought it looked partially potted. Repaired a little 2000 watt set once, because it quit making voltage. Replaced the $1.59 MOV from Radio Shack and it was back in business.
I guess it's a matter of how important it is to you as to whether to pay the $48+ to R&R the assembly. I found the same module elsewhere on the internet for the same price Sears quoted you. If a guy knew the resistance of the field, and the proper AC voltage level to the rectifier, you could build it for quite a bit cheaper (and more robust).

Is the potting material a varnish-hard type of substance, or is it more like 3-week old jello? If the softer kind you may be able to dig it out of there. Could possibly even get the board out of the hardened stuff with small dremel tools and a ton of persistance (if you like a challenge!)

[Joe Stewart]

The resin appears to be the hard stuff. I guess I'll go to Sears tomorrow and order the replacement unit because I'd love to see this machine make electricity. I paid $51.00 for the whole generator off e-bay several months back and the kawasaki engine runs great! Hardly looks like theres but 20 hours on it! I sure appreciate the input, and this excellent forum which allows for this exchange of information! Joe Stewart

[Clyde M]

Please post the numbers that are printed on the back of the board, from the picture you posted (it's shape and location of mounting), I'd say it looks alot like the 84132 power regulator that goes in a Generac 4000XL. I have also noted that at least one other Craftsmen genset (5500)( generator side) was built by Generac. Wire numbers and colors the same etc... I do not know if Generac parts would be cheaper. Clyde

[Joe Stewart]

Thanks Clyde, the numbers on the back of the board are "9833". The numeral9 and the last 3 are slightly smaller than the 8 and the second 3 - not sure if this has any significance.

[B.Sparks]

The "9833" is probably a date code and not an actual part number.
9833 = made in the 33rd. week (August) of 1998.

[Kevin K]

I have had good results using a heat gun to soften hard epoxy, making it easy to remove. Be sure to record any numbers on the parts, and the resistor color code in case the parts are damaged due to overheating. In any event, I would replace all three parts.

[pugs]

According to what I have the Sears 328330 is a Generac 8846-0.

Generac sold its small generator division to Briggs and Stratton, so you can get parts there. Your part number is good if you add a GS to the end...and it has a list price of 48.50. However when I look at the parts breakdown for that generator...I cannot find that part...oops...scratch that, I found it. It is very strangely drawn.

Anway, there is a few pages of stuff to go through for checking the Generac Generators. I would strongly suggest finding someone in your area that might be able to copy the Generac pages for you or something...go through all the steps. It would stink to put a 50 dollar part in it only to burn it up again if the rotor or stator has issues.

[pugs]

Oops, I forgot. I have a similar one sitting in the shop...or it might be gone now. After all the tests, I found it probably needed a rotor or stator or both. The resistance tests are not very helpful with Generec...they will find a major problem but harder to find problems...another story. Basically you get to a point where you need to put a big dollar part in and try it...if that doesnt work then another big dollar part...for a cheapy generator...just ends up not being worth it.

But what I wanted to add is I have one here and I did some checking into an air filter for it because if I did get it working, it needed one. Well Generac sold the small generator division to Briggs. Ok, fine and dandy. Well Generac is who you need to go to for the Generac engine parts. Briggs for the generator end parts. Well Kawasaki made the engine on some of these. And Kawasaki sets up some deals with certain vendors that are "self servicing"...John Deere is the major one. Anyway, that means as a Kawasaki dealer they do not give me access to parts breakdowns or parts of those engines. If you can get one from Sears do it...otherwise you probably wont find one

[Joe Stewart]

Hey Pugs, thanks for all the info! That Generac model # will come in handy. Anyway, I ordered the rectifier from Sears about three days ago. Paid $48.50 for the part but it came out to $63.00 when you add shipping and tax. I haven't recieved the part yet. I'm keeping my fingers crossed that it will do the trick and get this beast generating. I suppose that if it doesn't work, I'll separate the engine from the gen end and sell the motor on ebay - that seems like a shame though - like I said, this machine looks like a low hours unit.

There's a parts breakdown for this generator and engine on the sears website, but like you mentioned, its not that detailed (for example, this rectifier as diagrammed does not look like the actual part from my machine).

Thanks to all for taking the time to address this issue! Joe Stewart

[pugs]

No problem. That part number you had is the old Generac #. If you need anything else for it you can probably use the Sears breakdown/numbers. Just take them to your local Briggs "power products" dealer. Actually any briggs dealer should do. You may need to put a GS on the end of the numbers or they may forward to something else entirely.

I might still have that one laying around here somewhere...I forget if I junked it or not. Its a nice little engine, its just too bad Kawasaki wont sell parts for it and that it has a tapered shaft so its kinda useless except for use in another Generac

[Joe Stewart]

OK, I recieved the replacement rectifier board from Sears and installed it. I started up the engine and measured output voltage with no load and it reads 121 volts. I was excited to think it was fixed, but then over the next couple of minutes of running, the voltage progressively dropped to 80 volts. At about five minutes it was down to 70 volts, so I shut it down. I did not have a frequency meter. The rectifier board was hot, mostly that black square thing that rises up out of the hard resin. I let it sit overnight and I went back out there this morning and started it up again - 120 volts immediately at start up. I shut it down immediately this time so I could do a little more investigating. Any ideas on what the problem could be? This really makes me wonder if the original rectifier board was doing this same thing. I may put the old one back in later today and see.

There was another part on the Sears parts diagram called the "diode assembly" part #67462 on the Sears website diagram. Could this be the problem? I see the part on the Sears diagram, but I cannot see the corresponding part on my generator. I was curious so I ordered this part also since it was only $13.00. Its back ordered though and has not arrived yet. All advice and ideas greatly appreciated! Joe Stewart

[Joe Stewart]

I was going to post a link to the Sears parts diagram so you can see how crappy it is, but it won't let me post a direct link. You would have to go to http://www3.sears.com/ and type in the model number which is 580.328330 and then go to the parts diagram for the stator assembly. The diode part referenced above is #37 on the diagram. The rectifier board which I just replaced is #28. Thanks

[BTPost]

Sounds like you have a problem with some shorted turns in the field winding,
that is causing more field current than the recitifers can safely provide,
without overtemping. Since this is not a rotating recifier, I would stick
an ammeter in the field circuit and see what the field current is, with no
load, and what it is with a 55% load, then compare that current, with what
the field diodes are rated for.

Bruce in alaska

[pugs]

Did you ever try putting 12 volts to the brushes and seeing what the output was at that time? Also if you can do a rotor current draw test. May give you some more info. Basically measure the resistance of the rotor across the slip rings and also measure the voltage fo the battery before you start the test. Calculate the current that the rotor should draw when you hook the battery up to it. Then hook it up and start the generator. Measure what it does draw while up and spinning. IMPORTANT: Put a small fuse in line with this test so you do not damage your meter. If it draws about what you calculated it is ok, if it does not you have problems. Also something very simple...if you hook 12 volts to the brushes you should get a constant output. It may not be 120V AC but it should stay constant as long as the battery voltage is constant. If it drops off...you have bigger problems. Basically this should eliminate any electronics and tell you if your rotor and stator are working.

Unfortunately it is looking like you have issues with the stator or rotor or both

If you want I can post all those rotor and stator resistance numbers later tonight...but basically as long as you have continuity between similar wires and no shorts to ground that is about all it will tell you. Doesnt mean it is good since heat and the forces when running it are different than when sitting still...