I have used DB electrical for a number of years mostly for starters and alternators for odd ball equipment like I needed a starter for a Cushman truckster. I need a alternator and starter for a Deutz power unit. I installed several of there 24V to 12V kits on JD tractors over the years. I have never had any issues with anything I have bought from them.
L275 alternator not charging. Diagnose & overhaul questions
- Thread starter timsch
- Start date
Thanks all for the inputs, and specifically the recommendations for alternative suppliers. I didn't know about either of those two places mentioned above before this. That's comforting to know.
Got the rotor out. Bearing stayed in the housing, but it appears to be in good shape. Brushes move freely & look good as do the surfaces on the rotor they contact. The rotor passes continuity tests as i've seen online.
Checking the stator windings, one video said there should be no continuity between any of the three pairs (roughly 10, 2 & 6 o'clock below) . The three had continuity between 10 & 2. None between either of those 2 or those @ 6.
There is some flaking off of what looks to be copper material. A missing section is seen at the bottom of the following pic.
Checking the stator windings, one video said there should be no continuity between any of the three pairs (roughly 10, 2 & 6 o'clock below) . The three had continuity between 10 & 2. None between either of those 2 or those @ 6.
There is some flaking off of what looks to be copper material. A missing section is seen at the bottom of the following pic.
So one phase is missing (@6). Check the solder joints and for broken wires and broken tracks on the board that holds the bolts. And maybe corrosion around the contact bolts.
The flaky stuff is paint peeling of the rusting stator. Nothing to worry about. You can try to clean it up a bit and maybe give it a bit of rust protection (wax etc.) but be very careful not to scratch the green laquer of the copper winding.
With respect to the bearings I would replace them if excessive force had gone over the balls when pulling out the rotor.
edit: if you reuse the bearings I would take the cover disks off, clean out the old grease and give them fresh grease (not too much, excessive filling leads to heat buildup).
The flaky stuff is paint peeling of the rusting stator. Nothing to worry about. You can try to clean it up a bit and maybe give it a bit of rust protection (wax etc.) but be very careful not to scratch the green laquer of the copper winding.
With respect to the bearings I would replace them if excessive force had gone over the balls when pulling out the rotor.
edit: if you reuse the bearings I would take the cover disks off, clean out the old grease and give them fresh grease (not too much, excessive filling leads to heat buildup).
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I found this website, for example: https://alternatorparts.com/
Also aliexpress.com has a lot of alternator parts.
Since I use duckduckgo.com as a search engine I find much more and different web shops compared to google. I think if you do not pay enough protection money to the latter they will not show your web site.
When I did the continuity check I posted on above, I measured across each pair (10, 2 & 6 o'clock). All had continuity. I then measured between adjacent pairs and also got continuity, which according to this video are supposed to be isolated. I rechecked, and I have continuity between all 3 adjacent pairs (10-2, 2-6, 6-10). No obvious problems with the wires that I see, although now that I don't have to be concerned about the flaking bits, I can clean a bit more agressively.
Reading your response, Hugo, it looks like you're stating that the one that didn't have continuity is the one that is the problem. I probably didn't describe what I did well enough previously about where I had continuity. If I'm misunderstanding, let me know.
Reading your response, Hugo, it looks like you're stating that the one that didn't have continuity is the one that is the problem. I probably didn't describe what I did well enough previously about where I had continuity. If I'm misunderstanding, let me know.
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If the three bolts are the stator winding directly they should all have continuity. But there could be rectifier diodes on the board where the stator windings are soldered. In this case continuity depends on the voltage polarity of the Ohmmeter. Earlier generators had external diodes, later ones had the Diodes integrated in this plate.
Here is an internal diagram of a generator where you can see the three phase stator and the rectifier diodes:
Do you have a workshop manual for your tractor? The details of the generator would be described in there.
Here is an internal diagram of a generator where you can see the three phase stator and the rectifier diodes:
Do you have a workshop manual for your tractor? The details of the generator would be described in there.
Yes, I do have the shop manual, and it does have a good diagnostic section that I'm working through. It shows the stator and diode plate separated in this graphic
Top-side of diode plate is shown in post #23. Here's the underside:
Are the diodes fixed to the plate and the wiring coming in from below to be soldered in? Do i heat the diode on top to pull the wire out the bottom? I don't suppose the diagnostic check steps for the diodes can work with them wired up.
Top-side of diode plate is shown in post #23. Here's the underside:
Are the diodes fixed to the plate and the wiring coming in from below to be soldered in? Do i heat the diode on top to pull the wire out the bottom? I don't suppose the diagnostic check steps for the diodes can work with them wired up.
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The stator resistance is way too low to be able to measure the diodes with the stator connected. You have to desolder the stator wires first. If you find shorted diodes it is not a mistake to replace all of them. Due to excessive current even the ones measuring good may be damaged already and fail later.
I am not familiar with this type of diode board. The ones I know have really fat diodes pressed into an aluminium carrier. Maybe you can take more pictures of top and bottom of the board.
I am not familiar with this type of diode board. The ones I know have really fat diodes pressed into an aluminium carrier. Maybe you can take more pictures of top and bottom of the board.
Thanks for all the assistance. I'm planning on putting it back together and testing again rather than tearing it down any further. Nothing looks bad so far internally and it all checks out so far, so I need to step back a bit.
I realize I had a major short between the ears on one of my 1st checks, so will start over, hopefully with my head somewhere other than in me arse.
I realize I had a major short between the ears on one of my 1st checks, so will start over, hopefully with my head somewhere other than in me arse.
And please report back, so that this thread can be of help to others.
Removing the stator wires is not that difficult. Do you have a decent soldering iron with enough heat output (50W ish and short, wide tip for good heat flow)? I would really test the diodes, now that you have come that far taking it apart.
I am not sure, with your initial post, do you suspect it to be faulty? The 12.5V you mentioned, was that engine running? If yes, this would be too low. Should be more like 13.6 - 14V, depending on temperature.
edit: sorry, your headline said it, missed that.
Removing the stator wires is not that difficult. Do you have a decent soldering iron with enough heat output (50W ish and short, wide tip for good heat flow)? I would really test the diodes, now that you have come that far taking it apart.
I am not sure, with your initial post, do you suspect it to be faulty? The 12.5V you mentioned, was that engine running? If yes, this would be too low. Should be more like 13.6 - 14V, depending on temperature.
edit: sorry, your headline said it, missed that.
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With all the corrosion on the diode plate assembly, it might be hard to get any correct and true readings in a diode test.
Do you have a way to clean the diode plate assembly? Such as a soda blaster, or even a very light & quick sand blasting with some very fine abbrasives. From the looks of it the pictures, the plate's isolators may be compromised with all the corrosion between the upper/lower plates, etc.
Also, it looks like your assembly will have 6 button type diodes between those plates. Somewhere under the corrosion, those plates are most likely (or were likely at one time) marked "positive" and "negative" to show the proper placement of the diodes polarity.
The diodes are sandwiched between the plates under those "bumps". There may be corrosion under those plates between the diodes preventing proper contact of the diodes. You may need to find a way to seperate the plates to properly clean all the contact points. Pay attention to the polarity of the diodes on each half of the assembly so that if they all clean up and test ok....you can reinstall them with the proper polarity positioning before reassembly.
It's alot of work to save $100, but the knowledge gained greatly offsets that. By the way, in one of your earlier pics showing a missing piece under the stator wiring (green wires): That material is some type of fiberboard insulation that protects and insulates the wires from the stator lamination plates. There's also fiber "tubes" in the slots that serve the same function of protecting the windings.
Sure, I'll keep this thread updated until it's resolved one way or the other. I do have a soldering iron with a wide tip that should be strong enough. I have a soldering gun if needed. I assume I apply heat to what's called the "outside terminal" in the pasted Fig.79 above and pull the wire out from below. Let me know if it's otherwise.
I do have a small sand blast cabinet that I can use to clean these parts with. And yes, it's not about saving the money - it's all about adding to my vast jack of all trades master of none toolkit.
I do have a small sand blast cabinet that I can use to clean these parts with. And yes, it's not about saving the money - it's all about adding to my vast jack of all trades master of none toolkit.
Since you have both a soldering iron and gun, you probably know about and also have what's called a "solder sucker". If not; It can be a necessary tool to help desolder and seperate components. A pretty simple device that once you heat the soldered connection and activate the "sucker" will suck up the molten solder from the joint. It can take a few tries to get most of the solder out of the joint.
Desoldering all the joints of a particular component and breaking the last little "bond" at each joint will make removing those components much more easier.
Looking forward to seeing what's between those diode plates and the condition of the insides. It almost looks like removing those insulating washers will let you lift one plate up and off each side in order to get at the diodes? They might need a little persuasion to seperate after all these years. From the labeling on your diode plate.... those are likely 50 amp rated diodes inside.
xrocketengineer
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BX1880, FEL, Grapple, 36 in. Forks, 48in. MMM, Quick Spade, Ripper
That looks like it. Good to know. It'll be a few days before I can get back to this. Thanks all. I'll update before long.