Guest Anything-but Posted October 4, 2018 Share Posted October 4, 2018 Just about to pull off the M25 today and the abs light started flashing, "bugger" I think to myself. Carry on a few miles home and it starts spluttering and then dies, immediately suspected the battery to be faulty, so get a new one, give it a charge and fit it. Skip to a few hours later and it happens again! Had to call the Rac this time and once he had his multimeter on it clearly wasn't charging. Now, before I buy the bits, would this be the regulator or alternator at fault and how could/should I check? Cheers. Link to post
Andy m 23,544 Posted October 4, 2018 Share Posted October 4, 2018 Sorry to hear of your trouble. The alternator has three wires, usually black that go into the regulator. Go across these in pairs and check each pair has a resistance and is similar. These are the alternator windings. If you can, start the bike and do AC volts across each pair. Be careful, go in the back of the plug with it connected if you can. Typically 90V AC. Check the regulator has a good earth. If 3x88V is getting to the alternator and nothing is coming out you have a condition known as a ****** regulator. If in doubt just change the regulator, its the cheapest bit and they do fail. Giggle all plugs and buzz out the loom first though. Andy Link to post
Guest Anything-but Posted October 4, 2018 Share Posted October 4, 2018 11 minutes ago, Andy m said: Snip.. Yea, was pretty much going to grab the regulator 1st as I always found Honda and robust regulators don't make good bed fellows. Can't for the life of me find my multimeter so that'll be the 1st port of call tomorrow before the real cash gets splashed! Bty, is the reg specific to my model... '15 NC750X... or does the earlier Nc700s/x ones fit? Link to post
trisaki 2,029 Posted October 4, 2018 Share Posted October 4, 2018 2 hours ago, Anything-but said: Yea, was pretty much going to grab the regulator 1st as I always found Honda and robust regulators don't make good bed fellows. Can't for the life of me find my multimeter so that'll be the 1st port of call tomorrow before the real cash gets splashed! Bty, is the reg specific to my model... '15 NC750X... or does the earlier Nc700s/x ones fit? Check part numbers on Fowlers web site -same numbers mean same part Link to post
embee 7,288 Posted October 4, 2018 Share Posted October 4, 2018 (edited) As discussed elsewhere, the MOSFET reg/recs as fitted to the NC are very reliable. It's worth checking the connector first. The 3 wires from the alternator can sometimes get burnt terminals in the plugs and sockets, common in some other bikes, and usually you can just renew the connections. I've used simple crimp spade connectors when fitting the MOSFET items to other bikes, the 3 wires from the alternator can go to any of the 3 wires into the reg/rec. You just need to make sure you get the output wires the correct way round. This image is a typical sort of item, taken from google (Not an NC) The wiring diag for the 700 shows the plugs/sockets are directly on the reg/rec (no flying leads), usual 3 yellow from the alternator, red pos and green neg output. Edited October 4, 2018 by embee 3 Link to post
SteveThackery 3,090 Posted October 4, 2018 Share Posted October 4, 2018 Do alternators fail much, these days? I don't have access to any data, but I would have thought them to be extremely reliable, due to their great simplicity - a magnetic rotor and some coils of wire. Putting aside physical damage, probably only vibration could induce a failure, and that would be at one of the internal connections. I wouldn't be surprised if they will survive being run into a short circuit. 1 Link to post
kayz1 2,928 Posted October 5, 2018 Share Posted October 5, 2018 (edited) I have a 700x dct alternator here if needed..if it fits and you have a manual bike it will give you a few more watts: Edited October 5, 2018 by kayz1 Link to post
Andy m 23,544 Posted October 5, 2018 Share Posted October 5, 2018 8 hours ago, SteveThackery said: Do alternators fail much, these days? Things like coils don't, its connections. Speed up a flow soldering line, change the supplier of cleaning fluids, replace soldering with bonding or crimping, push a tool to a few extra units. There is little room for growth, not many people in Europe or the US need a third car, not many in India can afford a second one. Things started to last longer when the Japanese used quality as a way to break into the market and the Koreans and so on followed, there are fewer replacements required. The manufacturers are under pressure to make more, so they drive down costs. The tweaking to save 2p per million units is what can leave you with problems. You could have an NC that would do 100000 miles with nothing but oil changes for £20k purchase price. We'd all buy Tracers because they are cheaper and have a bigger choice of colour! Andy 3 Link to post
embee 7,288 Posted October 5, 2018 Share Posted October 5, 2018 This is a very good fault finding guide if you want to do thorough checks, applicable to most bikes with permanent magnet rotor alternators. https://cdn.shopify.com/s/files/1/1091/5694/files/fault-finding-diagram.pdf?235929069374954073 2 Link to post
Guest Anything-but Posted October 5, 2018 Share Posted October 5, 2018 9 hours ago, kayz1 said: I have a 700x dct alternator here if needed..if it fits and you have a manual bike it will give you a few more watts: Been trying to check this with fowlers, but none listed of my model to cross reference the part number (unless more knowledgeable people have experience)? But thanks everyone for the pointers, will be getting my hands dirty today so will update later on. Link to post
Guest Anything-but Posted October 5, 2018 Share Posted October 5, 2018 4 minutes ago, embee said: This is a very good fault finding guide if you want to do thorough checks, applicable to most bikes with permanent magnet rotor alternators. https://cdn.shopify.com/s/files/1/1091/5694/files/fault-finding-diagram.pdf?235929069374954073 That'll definitely come in handy later, ty. Link to post
kayz1 2,928 Posted October 5, 2018 Share Posted October 5, 2018 Alternator number:: 29122 that is all that is stamped on it. Lyn Link to post
Guest Anything-but Posted October 5, 2018 Share Posted October 5, 2018 (edited) Well, with a reading of 0.3 ohms across all three wires I think you can say the alternator is toast. Guess at least I know what I have to buy now.... Everyone, would @kayz1 700x dct alternator fit my 750x without issues? Edited October 5, 2018 by Anything-but Link to post
Andy m 23,544 Posted October 5, 2018 Share Posted October 5, 2018 (edited) I'd say the opposite. This is a coil of wire so only variable in length and of low resistance. It seems unlikely all three are burnt out just enough not to go open circuit? The CB500 manual gives the coil resistances as 0.1 to 1 Ohm. Andy Edited October 5, 2018 by Andy m 1 Link to post
Guest Anything-but Posted October 5, 2018 Share Posted October 5, 2018 Hmmm, was going by the pdf posted above in section B, second step. What had actually happened was i'd changed the chain/sprockets 2 weeks back and i must have missed placing the wire out of harms way and it'd worn through on 2 of the wires (yea, possibly a expensive mistake i won't make again), when re-connecting the wires is there a particular order/arrangement to have the three wires in the connector seeing as i still have one in situ? Link to post
Andy m 23,544 Posted October 5, 2018 Share Posted October 5, 2018 (edited) We've all done similar. Yellow is yellow, no particular order. Don't ask me to explain why though. When the "firing order" is changed, my DC/mechanical/pneumatic brain screams that it ought to suck instead of blow too. However, imagine three cams on a shaft with one big wide follower. When any cam comes up the follower jumps, so the order doesn't matter. Andy Edited October 5, 2018 by Andy m 1 Link to post
embee 7,288 Posted October 5, 2018 Share Posted October 5, 2018 1 hour ago, Anything-but said: Well, with a reading of 0.3 ohms across all three wires I think you can say the alternator is toast. You need to be really careful about trying to measure resistances of less than 0.5 Ohms (for example). Try connecting the meter probes directly together, they "ought" to read zero, but almost never will, it depends on whether the probe wires have been allowed for and if there is any zero offset either fixed or adjustable within the meter. I'm with Andy, if they all measure the same and it's something like 0.5 Ohms (0.3 will do) then it's probably fine. The resistance between each yellow phase wire and earth should be high (hundreds or thousands of Ohms). The yellow wires are all the same as far as the reg/rec is concerned, they can go in any order. See the wiring diagram picture, they are in "delta" configuration and it just uses the output from each pair, doesn't matter what order the pairs are in. 1 1 Link to post
Guest Anything-but Posted October 5, 2018 Share Posted October 5, 2018 Thanks, all duely noted, now to the next bit....re-attatching the wires. Crimped or soldered best resistance wise? Will be shrink wrapped after of course. Link to post
Andy m 23,544 Posted October 5, 2018 Share Posted October 5, 2018 I'm old school and vote solder. Proper automotive crimp and shrink work but you need the right tool. Andy Link to post
Spindizzy 7,109 Posted October 5, 2018 Share Posted October 5, 2018 Solder every time and heat shrink. Better still put some silicone sealant over the finished joint then heat shrink so it makes a weatherproof seal. Do it once properly and forget about it. 1 Link to post
Graham NZ 1,186 Posted October 5, 2018 Share Posted October 5, 2018 An informative thread. I like to crimp and then solder before shrink sleeve covering. 1 Link to post
tw586 88 Posted October 6, 2018 Share Posted October 6, 2018 solder is not recommended in automotive applications. heats up the copper wire and hardens it, the vibration causes it to start snap at the solder joint. Link to post
Graham NZ 1,186 Posted October 6, 2018 Share Posted October 6, 2018 1 hour ago, tw586 said: solder is not recommended in automotive applications. heats up the copper wire and hardens it, the vibration causes it to start snap at the solder joint. I suppose that could happen but so far, and that's a long way, no soldered connector has ever failed. I can't say the same for just-crimped connectors. I've seen many with high resistance through overheating and some of those were on cooker wiring! 1 Link to post
Andy m 23,544 Posted October 6, 2018 Share Posted October 6, 2018 (edited) 5 hours ago, tw586 said: solder is not recommended in automotive applications. heats up the copper wire and hardens it, the vibration causes it to start snap at the solder joint. Really? Every loom on a Scania, Volvo, DAF, Dennis bus, trailer and Land rover has soldered joints as well as crimps. For repair work both are used. You have to make sure the cover is doing its support job, mechanical and insulation. Crimps or screw fasteners are supplied to workshops where possible only because solder requires more skill and has additional safety issues. The crimp and heat gun type are very good and very easy to use. That said, a garage monkey using nut crackers and a fag lighter can make a mess of those too. Mostly plug together looms are supplied, lowest possible skill level, highest revenue. Andy Edited October 6, 2018 by Andy m Link to post
tw586 88 Posted October 6, 2018 Share Posted October 6, 2018 44 minutes ago, Andy m said: Really? Every loom on a Scania, Volvo, DAF, Dennis bus, trailer and Land rover has soldered joints as well as crimps. For repair work both are used. You have to make sure the cover is doing its support job, mechanical and insulation. Crimps or screw fasteners are supplied to workshops where possible only because solder requires more skill and has additional safety issues. The crimp and heat gun type are very good and very easy to use. That said, a garage monkey using nut crackers and a fag lighter can make a mess of those too. Mostly plug together looms are supplied, lowest possible skill level, highest revenue. Andy Its must be a European thing. I teach auto engineering here is Australia, specialise in heavy and industrial. none of our equipment ( teaching resources ) have soldered joints, and our communication std,s for CanBus stipulate no joint is to be soldered, all connectors are to be Crimped Deutsch pin and there is now the std for all main battery cabling both 12 and 24v must be crimped. We have had a bad run of truck and equipment fires when main cabling fails due to high resistance causing the solder connections to fail and short out starting fires 1 Link to post
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