wild foamy Posted July 9, 2009 Share Posted July 9, 2009 okay, so today i decided to investiagate my charging problems... having replaced the dial lights (most of which were blown) i couldnt get the battery light to go off, i tested the relay and that was fine, so i refered to my Jawa manual for some other checks and found my regulator to have burnt out one of its contacts (melted the solder on one of the spades) but even with that repaired i cannot get a charge. i then moved on to the regulator unit which should have a field current of around 2amps being fed to it from the alternator at terminal "DF", but that was stone dead. i tried switching in the ammeter straight off the alternator brushes but am still getting nothing off it. im pretty sure its my alternator, possibly the windings but am not sure if/how i can test them, ive just added new brushes and the alternator was partly dismantled when i got it, there seem to be two small blocks mounted on opposite sides of the alternator with a small off-centre plate rotating between them (the movement of this plate corresponds to the diodes flashing on my bridge rectifier) these blocks are adjustable and i did not have a referance when re-assembling the alternator, maybe this has something to do with it? is there a way to manually excite the alternator using another battery to see if i can then get it to charge? any ideas appreciated Steve-o (Battery was charged for testing, should have been enough to excite the alternator?) Link to comment Share on other sites More sharing options...
wild foamy Posted July 9, 2009 Author Share Posted July 9, 2009 anybody?, any ideas would be helpfull, im at a dead end (not to mention my wits end... ¬¬) according to my workshop manual the small blocks and rotor are the "contactless ignition", so i doubt that has anything to do with it Link to comment Share on other sites More sharing options...
JimR Posted July 9, 2009 Share Posted July 9, 2009 anybody?, any ideas would be helpfull, im at a dead end (not to mention my wits end... ¬¬) according to my workshop manual the small blocks and rotor are the "contactless ignition", so i doubt that has anything to do with it Hi Steve, I hope the brushes are long enough & their tracks (slip rings) are clean. If this the case that damm coil that lives around the rotor may have died a death Regards Jim Link to comment Share on other sites More sharing options...
wild foamy Posted July 9, 2009 Author Share Posted July 9, 2009 i changed the brushes so they are brand new and i can feel the springs compressing when i push the housing onto its mount on the alternator case. i didnt clean the slip ring when i did it though, perhaps this could be the problem? today i tried it again and was getting 1.0ohms of resistance through the stator windings, and at about 4000rpm managed to get 1 volt out of the rectifier Link to comment Share on other sites More sharing options...
wild foamy Posted July 10, 2009 Author Share Posted July 10, 2009 working on the assumption that the stator is good (due to low resistance readings) im going to assume that it is the slip rings may need a clean, i've been doing a lot more digging on the 'net and found these two sites: Alternator testing Cleaning generator slip rings and brushes The first one outlines procedures for testing the stator windings and rotor, The second site contains info regarding cleaning the sliprings on an RV generator (considering the construction of an alternator im assuming the principal is the same) so, bit of wet and dry on the end of a stick should sort it out, watch this space ... i dont know why i joined the air force as a mechanic, i should have been a sparkie, i'd be great at that... kit out the chinooks with neons, alloys and the biggest soundsystem i could cram into the carge hold... Link to comment Share on other sites More sharing options...
wild foamy Posted July 12, 2009 Author Share Posted July 12, 2009 Surely there is someone on here who knows a bit about electrics?!. ive now cleaned the slip rings and am getting a field current of 0.15amps and 2v @ 2000rpm from the regulator. maybe a diode?, how do i go about testing the alternator diodes?, or the diode in the rectifier? any ideas are welcome, i dont know what to check next Link to comment Share on other sites More sharing options...
wild foamy Posted July 12, 2009 Author Share Posted July 12, 2009 a mate of mine suggested running a wire from the positive terminal on the battery directly to the coil to manually energise it and create a field current to see if that makes it charge... would that work or am i just likely to end up laying on my back at the opposite end of the garden with no eyebrows? im heading over tomorrow bright and early to get to work on it, need to strip the forks down to get them rechromed (thanks JimR! ) and take the back brake off aswell so will give it a try EDIT: If it helps, here is a diagram of the alternator, regulator, rectifier and charge light relay Link to comment Share on other sites More sharing options...
JimR Posted July 13, 2009 Share Posted July 13, 2009 a mate of mine suggested running a wire from the positive terminal on the battery directly to the coil to manually energise it and create a field current to see if that makes it charge... would that work or am i just likely to end up laying on my back at the opposite end of the garden with no eyebrows? im heading over tomorrow bright and early to get to work on it, need to strip the forks down to get them rechromed (thanks JimR! ) and take the back brake off aswell so will give it a try EDIT: If it helps, here is a diagram of the alternator, regulator, rectifier and charge light relay Hi Steve try to 'uncomplex' the electrics if the brushes & rings are good and a good no load voltage is coming out of the genny wires (ac rather than dc) you should have 20v ish at this test. if you have that it would point to the regulator (in my day you could strip them and clean & adjust the points) but on your 'modern' bike you may have an ic type of regulator which may have gone down !!!! dependant on how the fork tubes get over here is a bit dependant on how the charging circut is checked .. I guess u have a meter ! Regards Jim Link to comment Share on other sites More sharing options...
wild foamy Posted July 13, 2009 Author Share Posted July 13, 2009 I guess u have a meter ! yes i have been using several, had a standard DC meter monitoring the battery voltage and a fancy auto-range multimeter checking the AC current from the genny to the regulator, think i was getting a very small voltage (talking 0.5 volt) of field charge but will check again when i am next over there, which will probably be sunday Link to comment Share on other sites More sharing options...
Moderator Airhead Posted July 13, 2009 Moderator Share Posted July 13, 2009 Surely there is someone on here who knows a bit about electrics?!. Here Link to comment Share on other sites More sharing options...
blackhat250 Posted July 13, 2009 Share Posted July 13, 2009 think i was getting a very small voltage (talking 0.5 volt) of field charge Stevey mate . this is wot weve been go-in thru with mates RD400, Rewound altnator/ Rotor/ New volt reg/ rectifier/ The coils were wired direct from kill switch[ handle.bar] . this pulled battery down quickly. So we put in a Resistor. "cured that" Still no charge . So wading thru all the hair on floor [ were both bald now] fitted replacement Wiring loom . CHARGING ,, 14.6 volts at battery yippee [ we thot] ran it last weekend . 120 mls fine Went in to garage at nt Battery low . NOT CHARGING AGAIN [ matches were considered] So we are pulling hair from parts of body that cant be mentioned ELECTRICS Link to comment Share on other sites More sharing options...
wild foamy Posted July 13, 2009 Author Share Posted July 13, 2009 i have many-a-time considered dousing this cursed jawa in petrol and setting fire to it, but now that ive got the brakes and hopefully the forks sorted, that would be silly. if worst comes to worst i will put a car battery in a topbox and run it from that and charge it every week Link to comment Share on other sites More sharing options...
JimR Posted July 14, 2009 Share Posted July 14, 2009 i have many-a-time considered dousing this cursed jawa in petrol and setting fire to it, but now that ive got the brakes and hopefully the forks sorted, that would be silly. if worst comes to worst i will put a car battery in a topbox and run it from that and charge it every week Hi Steve, the answer will be simples (merekat wise) ... if you go a no load voltage check from the genny and get nowt (no load being the genny unpluged from the loom and the voltage checked at this point .... older Jawa's (not yours ? ) used to run silly voltages across the genny terminals (50+) when disconnected. If you have that it would be good to deem the genny to be ok and sherlock (through deduction) would discount the rec/reg .. which leaves the wires .... perhaps as DR Watson Regards Jim Link to comment Share on other sites More sharing options...
wild foamy Posted July 14, 2009 Author Share Posted July 14, 2009 hmm, any chance of relating those voltage tests to the wiring diagram? im kinda lost theres sweet f/a coming off the genny from the rotor (well, about .15 volt last time i checked on the brushes) so where do i stick the multimeter to check for a no load voltage? (sarcastic replies will be ignored) Link to comment Share on other sites More sharing options...
barkwindjammer Posted July 15, 2009 Share Posted July 15, 2009 I can see a red wire and a green wire, electrics baffle me Link to comment Share on other sites More sharing options...
wild foamy Posted July 15, 2009 Author Share Posted July 15, 2009 I can see a red wire and a green wire, electrics baffle me dont s'pose you got that in english? Link to comment Share on other sites More sharing options...
wild foamy Posted July 16, 2009 Author Share Posted July 16, 2009 spoke to an auto electrician today who suggested replacing the zener diode as it has most likely been damaged (plastic casing around it has melted and the solder on one of the tags had burnt off) anyone know what replacement zener diode i need?, if this dont fix the feckin thing it will be down the scrapyard, Link to comment Share on other sites More sharing options...
barkwindjammer Posted July 16, 2009 Share Posted July 16, 2009 Maplins?, if theres one near you, that cant be a difficult part to find I wouldnt think, ask the sparks at the RAF Link to comment Share on other sites More sharing options...
barkwindjammer Posted July 16, 2009 Share Posted July 16, 2009 on your wiring diagram I counted 6 diodes, are they all zener diodes?, Link to comment Share on other sites More sharing options...
wild foamy Posted July 16, 2009 Author Share Posted July 16, 2009 nope, feck knows what is going on with that wiring diagram. basically where those 6 diodes are i have just one big zener diode sat in the middle of a heatsink found some diodes and regulators on a website appropriately named FEKED EDIT: BWJ, maybe this will answer your question; Back in the 60s and 70s a lot of the little bikes had these single wave rectifiers. Now most bikes have full wave rectifiers that have four diodes Link to comment Share on other sites More sharing options...
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