Well the neighbour just bought an old toyota landcruiser. It appeared alright, but the alternator had packed up. This is usually just replaced with anything out of some other rusting hulk over here. The salt kills off the bodies long before the motors give out on this island.
The difference with this Toyota, was that the alternator had an oil gear pump intergrated into the rear of it, and it would be very difficult to find a similar one.... so it ended up at my place.
I did a few cursory checks, and decided that it had to come out. (it didn't bloodywell work)
It was messy to dismantle with the gear/oil pump on the back dribbling all over the table, but it appeared to have burnt three diodes out.
No, not the biggies, but the three small ones that supply voltage to the "control block".... now this can't be good.
Upon inspection, the regulator was integrated with the brush holder and an aluminium diecast box moulded into the top of the assembly obviously contained a control mechanism..... damn.
It's owner looked at the blackened mess on the bench and looked pretty sick ...just thinking about the time it will take to find a replacement on the mainland, and to get it shipped over here...... not to mention the cost.
An overwhelming pity came over me as I have been waiting for months now for my fibreglass to turn up to do my stator..... i weakened and said "yeah we can fix that".. The owner took on a new demeaner and wandered of confidantly that all would be well....oztules said so.
.... some times I wish I would just shut up and stop trying to be so helpful.
I unbolted the brush housing and pryed off the diecast thinggy, and found it was about an inch square,and 3/8th inch deep and full of black rubber. Somewhere in the rubber must be the volatage reg.....suddenly I don't feel too chipper and begin to think that I've bitten off more than I can chew. Why the hell can't they build em so's you can fixem..... It's not too much to ask surely.
Well I got the trusty heat gun and hoped that the rubberised stuff would melt and come out, leaving me a circuit board I could possibly decifer and fix..... I don't know where I get these optomistic ideas from.
The casting got stinking hot, the rubber didn't melt, and the circuit was never going to be revealed.... this was for keeps. After toasting my pinkies on the alloy a few times, I unceromoniously slipped the flatblade screwdriver into the stinking hot rubber, and ripped and tore and swore, and eventually the rubber came out in bits..... with little silver blobs in it about 1-2 mm across. These were the resistors and transistors mingled with the rubber. A surface mount fet or similar came out as well..... then a tiny circuit board with no holes in it.
Yep, you guessed it, surface mount technology, rubberised into the casting for a good "sealed forever arrangement". There was no hope in hell of fixing this now, the parts were distributed evenly in the rubber, and the circuit board had not a single component left on it, the hot rubber had removed them without trace....... this is past the point of no return.
First things first i decided, we'll fix the alternator, and then worry about the regulator.
So I replaced the little 1 amp or so diodes with some 6 amp/ 100amp surge types 700v... lets see em blow those up i sniggered. They had welded themselves into the plastic coated steel diode block, but his was easy to overcome as it was only physical difficulties. In ten minuites I had success, I had replaced three diodes.... whooppee...yahoo............. big deal. The excitement quickly faded.
It suddenly dawned on me that I had never built an alternator regulator before, and resolved to build a miniture regulator that could replace any reg in any alt in the future, and it is this that prompted me to put this in a diary.... some other poor slob may run into this problem, and here is a solution . There are probably better ones, but in the isolated back of beyond, this is doable.
I designed this board and etched half a dozen at once on a 3" piece of circuit board. Drilled it and soldered in the bits.
The composite jpeg is unweildly,
but the pcb will give you all the info required
http://www.otherpower.com/images/scimages/5171/altreg.pcb
You will need to get autotrax off the net (free version) to read and use this file
Tested it and found the best fit resistors for 14.1v. worked on the test bench.... but it still didn't fit the alumunium housing the surface mount board came out of.... it was too high.
So I milled the alloy down 1/16th" deeper and the board now just fits into it.
It uses a darlington fed by a zener bridge to establish the voltage plateau. when v>14.1, no voltage to the brushes, when v<14v, then voltage to the brushes. With just a dash of of hysteresis it is a simple but effective voltage regulator and will get you out of some expensive problems when your too far away from a good source...also the numbers were worn off the alt, so getting a match was going to be a real problem...every parts person wants the part number or no deal.
So If you have a hard to replace alternator that's just given out, check/replace the diodes, build this little controller, and it will work once more. (chance of the stator basket or the rotor being cactus is remote, and you could rewind if necessary) Parts were about three dollars, and it could have been used outside the alt housing, I just wanted it to be just like the original.... except working.
You could also use it to change the voltage to 24 or whatever as well, just by changing the zener or the resistor bridge.
Now it was just a matter of payment.... I decided that we'd do it the usual way...if he provided the beer, I'd provide a 20' high stack of tea trees from clearing the fenceline last year, and we'd have a bloody big bonfire and a few tinnies in the afternoon sun.... coz that's how we do things over here in winter.
(The fenceline was a few kilometers long, plenty more burning off to go.)
I feel I'm havin way too much fun...
..............oztules
