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Discussion Starter · #1 ·
Hi All,
Out for a ride the other day and my recently acquired T140 died on me due to electronic failure. Its a 1978 T140V but with Boyer Bransden electronic ignition. I found a fuse had blown so tried the spare I carry with me and that blew immediately even with the ignition off. When I got the bike home I found the zener diode had been shorting, the insulator had melted, the diode had shorted and transferred metal to a nearby lead to the coil. I removed the diode which was in visibly poor condition and found it had short circuited as my meter was reading to infinity in each direction. With the diode still unattached I replaced the fuse - this time it didn't blow and my electrics, lights, etc were working again. Although my knowledge of electrics is very poor I'm fairly confident as a result of all this that the diode is faulty and needs replacing.

My questions are:
1) will the diode failing have caused any other damage, particularly to the electronic ignition?

2) is it ok to see if the bike will start without the diode connected and run it very briefly to see if everything else is working or?

3) the zener diode was mounted to the plate on the frame near the oil filler in the position shown by the screwdriver in the photos below and there is a good coat of paint on the frame. The diode did appear to be earthing here but probably didn't get a lot of air circulation to cool it in this position so I'm wondering if overheating caused it to fail. Is this location suitable for the diode or should it be moved?

Many thanks for any advice given.
Graham


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The zener is a rather crude method to prevent the battery from being overcharged/boiled dry. Insulate the wire to the zener and go ahead and start the bike. My guess is the failed zener did nothing to anything else. That's what the fuse was for. Protected the wiring from overheating.

Suggest you go with a more modern regulator/rectifier. Just keep in mind that there is a slight leakage to ground with Podtronics and Tympaniums that will draw down the battery over extended parking periods (I'm walking weeks/months, not days). Although the instruction say to wire them so they are connected directly to the battery, I prefer to either connect them thru the igntion switch so they are disconnected when the switch is off, or thru a relay that is turned on and off by the ignition switch.

John Healy will tell you that there is no leakage to ground. But Bob Kizer (RIP), the man who created the Pod said there is. And I personally had one draw down the battery on a parked vintage bike. Installed a relay to switch the connection to the battery on and off and problem went away. Only ride that particular bike a couple times a year.
 

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the zenner should be fitted to a "heat sink" - normally the original ali air box - or an ali plate if the air boxes are removed -- this may be why the Zenner cooked itself
as Snakeoil suggests - convert to a modern reg /rec - much better and similar cost
 

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Hi Graham,
is it ok to see if the bike will start without the diode connected and run it very briefly to see if everything else is working?
(y) But turn on all the lamps before attempting to start the engine and don't rev the engine.

the zener diode was mounted to the plate on the frame near the oil filler in the position shown by the screwdriver in the photo
The diode did appear to be earthing here but probably didn't get a lot of air circulation
The plate should've had an area of at least 25 square inches. The air flow in that position would've been fine (original Zener heatsinks were located behind the left-hand sidepanel) if the plate was large enough.

Is this location suitable for the diode or should it be moved?
Irrelevant; as @Snakeoil Rob and @wol have posted, replace the dead Zener and the separate rectifier with a combined regulator/rectifier. Reasons are:-

. current new Zeners are unreliable, at least some have been known to allow DC to rise to 19V, which'll kill the bike's EI; (n)

. new Zeners are more expensive certainly than the cheapest of the two regulator/rectifiers listed below.

Regulator/rectifier ("reg./rec.")
keep in mind that there is a slight leakage to ground with Podtronics and Tympaniums that will draw down the battery over extended parking periods
Simple answer is you wouldn't use a Tymp and, if you fancy a Pod, use the 3-phase one; however, there's a cheaper alternative that's just as reliable. (y)

Longer answer - If the alternator stator has two wires out of the primary, it's original '78 low-output or replacement single-phase, it can be connected to a 3-phase reg./rec. The reason you'd use a 3-phase reg./rec. is, if you ever want/have to change the stator, they're all the same physical size and they all cost pretty-much the same ... so logically(?) you'd buy a high-output 3-phase as that'd be "the most bang for your buck". Were you to follow that logic, if you bought a 3-phase reg./rec. now, any new stator can be connected to it in the future. (y)

Currently, the cheapest 3-phase reg./rec. is Regulator Rectifier & 5 Way Male Plug For Honda CB250 CBR400 CBR600 900RR 1100XX | eBay - be aware this is a particularly good deal as it includes the connecting plug; however, there are only two available; normally the reg./rec. and plug have to be bought separately, although that isn't a big deal and not expensive.

Or the cheapest source for genuine Pod reg./rec. in GB I know of is TMS; if you scroll to the bottom of the linked webpage, "VR.10124/P SOLID STATE REGULATOR/RECTIFIER 12v THREE PHASE GENUINE PODTRONICS".

There are cheaper reg./rec. between the cost of the Ebay one and the cost of the Pod (e.g. the Wassell "LUCAS" one listed immediately above the Pod) but I just wouldn't.

I prefer to either connect them thru the igntion switch so they are disconnected when the switch is off
Snag with that is the ignition switch cannot disconnect the alternator from the ignition; the alternator is quite capable on its own of powering the ignition. (n)

I haven't read any posts on any forums by anyone whose bike is using either of the above 3-phase reg./rec. of any "leakage to ground"? In any event, you'd connect their DC wires directly to the corresponding battery terminals and include a fuse in one of the wires; if you had any concerns about "leakage to ground ... over extended parking periods", you'd just remove that fuse.

1978 T140V
found the zener diode had been shorting, the insulator had melted, the diode had shorted and transferred metal to a nearby lead to the coil.
zener diode was mounted to the plate on the frame near the oil filler in the position shown by the screwdriver in the photo
View attachment 793543
Mmmm ... there's a lot more going on in that photo. ...:-

. If the Zener was mounted on a plate by the oil filler, how did it reach that Red wire with the deposited metal? There appears to be exposed copper wire by the deposited metal; did the Zener come loose from the plate first and rub through the Red wire's insulation?

. The ignition coils mounting plate needs straightening. The bend suggests something very heavy pressed on it ... The visible coil's anti-vibe rubber appears to be perished; if so, new aren't expensive.

. The bike might be '78 but the wiring loom is '79-on, the Black wires out of it beside the Boyer-Bransden Transistor Box give it away:-

.. '79-on Triumphs were 'negative earth' as standard, the Lucas/British Standard colour code for 'negative earth' wires is Black;

.. pre-'79 Triumphs were 'positive earth' as standard, the Lucas/British Standard colour code for 'positive earth' wires is Red.

. Irrespective of whether your bike's electrics remain '78-standard 'positive earth' or have been converted to 'negative earth', the connections labelled on the B-B "Transistor Box" never change, White is always connected to negative, Red is always connected to positive, Black is always connected to only one coil negative.

. On top of the use of a '79-on wiring loom on a '78 bike, the wiring connecting the B-B "Transistor Box" to the B-B trigger unit "Stator" (under the circular cover on the engine timing chest) is even more piss-poor - Bransden used Black/White and Black/Yellow so he could repurpose existing points wires in pre-'79 harnesses. '79-on Triumphs had Lucas Rita EI, it used White/Orange and White/Purple to connect its "box" to its "trigger unit"; whoever wired your bike hacked off those short bits of White/Purple wire from the loom. (n)

Your next post, useful photos. would be:-

. the bike's battery terminals and connected wires;

. the bike's front end - speedo., tacho., idiot lamps, ignition switch position.

Hth.

Regards,
 

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Discussion Starter · #6 ·
Hi Stuart, thanks for the reply.

(y) But turn on all the lamps before attempting to start the engine and don't rev the engine.
I've just started it with lamps on and ran it very briefly, and was relieved that all seemed ok.

One of the regulator/rectifiers you suggest sounds like the best solution but I worry about my ability to wire it in correctly, particularly as the wiring has been 'modified, as you've noted. If this is very easy or I could be given a dummies guide I'd probably be ok. I would be reluctant to buy the unit from the ebay ref you gave me Regulator Rectifier & 5 Way Male Plug For Honda CB250 CBR400 CBR600 900RR 1100XX | eBay purely because the item is located in China. It may be ok, but I'd prefer to buy form a UK seller, even if I end up buying the same item at a higher price. I had thought a like for like Zener replacement would be simplest for me to do, but having read your warning about the new ones I'm not so keen on doing that. The 3-phase reg/recs you mention seem to have an extra wire connected to them (5 wires instead of 4 with single phase) - would this simply mean two would need joining together?

Mmmm ... there's a lot more going on in that photo. ...

If the Zener was mounted on a plate by the oil filler, how did it reach that Red wire with the deposited metal? There appears to be exposed copper wire by the deposited metal; did the Zener come loose from the plate first and rub through the Red wire's insulation?
I may have misled you when I mentioned a 'plate' - its not a plate as such, what I meant was the flat area below the filler port that is part of the frame. I've added some more photos below and the screwdriver is sitting in the hole previously occupied by the Zener. The paintwork probably 'insulated' the Zener to some extent. I had been thinking of transferring a new Zener to a heat sink, but not now if I go for the combined regulator/rectifier. The damaged red wire (to the LHS coil) looks like it may have been squashed under the Zener at some stage (though it wasn't under it when I removed the Zener this time) and looks like its overheated. I can't see any exposed copper wire (but see what you mean in the photo), though some may have been present beneath the blob of transferred metal. The wire was touching the diode and I guess that was shorting and arcing - there is a corresponding small blob on the side of the diode where these were in contact.

.On top of the use of a '79-on wiring loom on a '78 bike, the wiring connecting the B-B "Transistor Box" to the B-B trigger unit "Stator" (under the circular cover on the engine timing chest) is even more piss-poor - Bransden used Black/White and Black/Yellow so he could repurpose existing points wires in pre-'79 harnesses. '79-on Triumphs had Lucas Rita EI, it used White/Orange and White/Purple to connect its "box" to its "trigger unit"; whoever wired your bike hacked off those short bits of White/Purple wire from the loom.
"Piss-poor" describes a lot of this bike I'm afraid - a classic case of buying in haste and repenting at leisure. Although money has been spent on it there's a lot not right with it and its the only vehicle I've regretted buying in over 40 years of motoring. But enough of that.

Your next post, useful photos. would be:-

. the bike's battery terminals and connected wires;

. the bike's front end - speedo., tacho., idiot lamps, ignition switch position.
I've added some more photos which I hope are useful and would be grateful for further comments. Plenty more that is non standard as you'll see. Not sure where the switch gear came from but there seems to be a start button so maybe an ES model if from a T140 at all.

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No worries about an Ebay reg/rec from China, it has been residing in my Trident for 7 years without any problems. I believe Stuarts unit is as old or older. I will leave the rest of the questions for Stuart to answer, know nothing about differences between 78 and 79 Triumph loom.
 

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the handlebar switches you have are 79 onwards T140
the 3 wires to your rectifier suggest you may have a 3 wire alternator stator
main difference between 78 and 79 loms are relating to the 3 wire alternator and the associcated rectifier - may also include wiring for the electric start models
 

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Discussion Starter · #9 ·
the handlebar switches you have are 79 onwards T140
the 3 wires to your rectifier suggest you may have a 3 wire alternator stator
main difference between 78 and 79 loms are relating to the 3 wire alternator and the associcated rectifier - may also include wiring for the electric start models
Thanks for spotting that, I've just checked and there are 3 wires coming from the alternator.
 

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Discussion Starter · #10 ·
No worries about an Ebay reg/rec from China, it has been residing in my Trident for 7 years without any problems. I believe Stuarts unit is as old or older. I will leave the rest of the questions for Stuart to answer, know nothing about differences between 78 and 79 Triumph loom.
Thanks, maybe its worth a try then - the one thing I previously tried to buy direct from China via eBay never turned up so I didn't think I'd bother again. The feedback for the seller of this reg/rec isn't perfect either as some people have said they've not received their item.
 

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Hi Graham,
just started it with lamps on and ran it very briefly, and was relieved that all seemed ok.
🤞

added some more photos which I hope are useful
Very. (y)

Although the earlier brickbats for piss-poor wiring, View attachment 793605 appears to indicate the '79-on harness has basically been used to wire the bike's electrics 'negative earth'.

Nevertheless, you should confirm the Brown(?) wire connected to the battery positive terminal is connected to the Brown/Blue wires connected to the rectifier View attachment 793609 and were connected to the Zener View attachment 793540 .

However, then we return to the brickbats ... '79-on models grouped a different (4-position) ignition switch and the idiot lamps in a console usually mounted between speedo. 'n' tacho. (which also had different mountings). Otoh, your bike has the correct-for-'78 2-position (on/off) ignition switch mounted in the correct-for-'78 position ... So the wirer has bodged a connection between the end of the Brown/Blue wire and one of the wires to an ignition switch terminal View attachment 793610 - educated guesses again say the Purple/Yellow wire, the connection to the Brown/Blue is inside the headlamp shell?

Zener
screwdriver is sitting in the hole previously occupied by the Zener.
If the bike is wired 'negative earth', afaik you would have even greater difficulty obtaining a new Zener, as that has to be specifically 'negative earth' (most, if not all currently, available are 'positive earth' to suit standard pre-'79 electrics).

Damaged red wire
If this wire is the Boyer-Bransden Transistor Box Red wire, or is connected to it, as on the Box label, it's +ve; the other end of the wire on the LHS coil is connected specifically to the coil's "+" terminal?

While it's academic now:-

. if the wire's conductor strands aren't exposed, it can't have been "shorting and arcing"; (y)

. if exposed +ve strands had touched anything except the Zener's spade terminal, because it's 'negative earth', the fuse is only 20A, would've blown;

. otoh, squashed under the Zener, which gets hot when it's working, the wire's insulation would've been damaged by the heat. (n)

Regulator/rectifier
3 wires to your rectifier suggest you may have a 3 wire alternator stator
... that the rectifier is square View attachment 793609 confirms it and the stator are '79-on 3-phase. (y)

No worries about an Ebay reg/rec from China, it has been residing in my Trident for 7 years without any problems.
feedback for the seller of this reg/rec isn't perfect either as some people have said they've not received their item.
No worries, I only picked that one because it was the cheapest on Ebay and included the plug, there are any number of sellers of the same reg./rec. Next-cheapest is Voltage Rectifier Regulator For Honda CBR600F2/F3/F4 CBR900RR VT750 Shadow UK1 | eBay. However, you'll need to buy the matching plug separately, the seller of this one is located in GB, however2, it is almost twice the price of the cheapest from China.

worry about my ability to wire it in correctly
Understandable.

Either an Ebay reg./rec. plug or a Podtronics 3-phase will have three Yellow wires; these are connected each to one of the stator wires out of the primary; doesn't matter which to which as the alternator generates AC - Alternating Current. :)

Either an Ebay reg./rec. plug or a Podtronics will have a Red wire, this is DC+, connect it to the battery +ve terminal.

An Ebay reg./rec. plug will have a Green wire, a Podtronics will have a Black wire, these are DC-, connect it to the battery -ve terminal.

Either the DC+ wire or the DC- wire should have a blade fuse and holder in it. Without removing the primary chaincase, you won't know whether the stator is 10.5A @ 5,000 rpm or 14.5A @ 5,000 rpm so I advise another 20A fuse in the holder between reg./rec. and battery.

As you will need to connect bullet terminals to the Yellow wires ends, ring terminals to the Red and either Green or Black wires ends, and you'll want to fix the crappy wiring and replace the red- and blue-insulated Bodger's Terminals with properly-crimped and -insulated ones, I advise a pot of coffee or tea and work your way through Autosparks "Electrical Components" and Vehicle Wiring Products "Products" webpages.

You'll find correctly-coloured wire; comparing to the unmolested terminals from the main wiring loom, recognisably the same "4.7mm" bullet terminals and their black-insulated connectors, "6.3mm" spade terminals and their soft translucent plastic insulators, crimping tools for both terminal types, to replace the bodges.

If you make a list of what you think you might need with links and post it here, I'll be happy to run through it and advise any unnecessary or cheaper alternatives. Also, no need to go for the expensive tools or lots of terminals and insulators. Once you have them, you can do decent wiring. (y)

added some more photos which I hope are useful
View attachment 793606 You should investigate what this capacitor is doing ...

Standard 'negative earth' wiring with Boyer-Bransden EI, the White/Yellow wire should be between the "ENGINE STOP" switch View attachment 793611 and the same ignition coil "+" terminal as the B-B Red wire.

So no idea what the capacitor is doing between a Black wire and a White/Yellow wire ... unless either or both wires have been randomly hacked off the loom and reused. :rolleyes:

View attachment 793607 In addition to the bodged connection between '79-on wiring loom Brown/Blue wire and '78-position ignition switch, you should expect:-

. Potentially more bodging to the '78-position lever lighting switch ('79-on 4-position ignition switch also did lighting connections).

. '79-on had four idiot lamps - Blue main-beam warning, Amber indicators warning, Green neutral indicator, Red oil pressure warning. However, while a '79-on wiring loom will have the Slate (Grey) wire that connected the Green idiot lamp to the neutral switch, unless your bike's engine has '79-on cases with a '78 engine number stamped on 'em, the gearbox casing won't have anywhere to fit the neutral switch; if your bike has pre-'79 cases, no idea why the wirer drilled a fourth idiot lamp hole and filled it. :confused:

Hth.

Regards,
 

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Snag with that is the ignition switch cannot disconnect the alternator from the ignition; the alternator is quite capable on its own of powering the ignition. (n)
You took me out of context, Stuart. That sentence went on and said, " or thru a relay that is turned on and off by the ignition switch.". The point was to disconnect the reg/rect from the BATTERY when the bike is parked. I ended up using a relay on the bike that originally revealed the leakage path of the Pod.

I'm curious why you say not to use a Tympanium? I'm out of date on the latest products. My guess is cost for the Tymp compared to other options. ;)
 

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Hi Rob,
curious why you say not to use a Tympanium?
Initially because it can't handle more than a RM21's output - would have to be changed if an owner subsequently wanted a more-powerful alternator. (n) Also, Tymps have had potential involvement in at least a couple of stator failures posted on the Forum. (n)

In the event, @Alestorm Graham The OP's bike has a 3-phase stator, no suitable Tymp.

You took me out of context
Your complete sentence:-
I prefer to either connect them thru the igntion switch so they are disconnected when the switch is off, or thru a relay that is turned on and off by the ignition switch.
... "either ... or ..." is two separate alternatives, one detailed between "either" and "or", the other detailed after "or".

The "Snag" with the alternative detailed between "either" and "or" is "the ignition switch cannot disconnect the alternator from the ignition; the alternator is quite capable on its own of powering the ignition. (n)"

The point was to disconnect the reg/rect from the BATTERY when the bike is parked.
That's as maybe. However, your first alternative has the unintended consequence I highlighted. If you used a relay, just simply post that?

Hth.

Regards,
 

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My cheapo Chinese reg/rec, as seen above, drains 0.8 milliamp from the battery while the bike is parked. I measured it ten minutes ago.

Check my working, but I think that will take 52 days to consume 1 amp hour of battery capacity. If I parked the bike for months, I’d take a lead off the battery. The leads are only on spade connectors.

Wiring it for the key switch to isolate the reg/rec from the battery and then fitting relays to isolate the charging system from the ignition is not sensible, unless your reg/rec has a much greater parasitic current drain than mine.
 

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Discussion Starter · #15 ·
Hi Stuart,
Thank you again for the reply.
Although the earlier brickbats for piss-poor wiring, View attachment 793605 appears to indicate the '79-on harness has basically been used to wire the bike's electrics 'negative earth'.

Nevertheless, you should confirm the Brown(?) wire connected to the battery positive terminal is connected to the Brown/Blue wires connected to the rectifier View attachment 793609 and were connected to the Zener View attachment 793540 .
I'm pretty confident the bike is negative earth. The brown cloth covered wire goes into to the spade fuse holder and a similar wire from the other side of this is connected to a brown/blue wire. A continuity test indicates that this brown/blue wire is connected to the rectifier and in turn to the Zener. In addition a continuity test between the -ve terminal on the battery and an earth point on the frame reads infinity (zero), and, with my multimeter set to 20v, I get a reading of 12.87v if I connect the positive probe to the +ve on the battery and the negative one to the same earth point.

Zener
If the bike is wired 'negative earth', afaik you would have even greater difficulty obtaining a new Zener, as that has to be specifically 'negative earth' (most, if not all currently, available are 'positive earth' to suit standard pre-'79 electrics).
There were a couple of zeners advertised as negative earth on ebay the other day, this one (now sold) for eg, Genuine Lucas 49589 Zener Diode Negative Earth for Triumph/BSA/ Norton | eBay, though I assume that what looks like a + sign on it doesn't refer to the earthing. As a point of interest, would a Zener of this type have been used on a bike with a three phase alternator, as we've established mine is, and/or in conjunction with electronic ignition (ignition may not be relevant I guess as the Zener is to do with (over)charging)? My reason for asking is that I also saw this one for '81-'83 bikes which specifically says its for 3 phase. I wonder if the Zener I had wasn't up to the job in the first place - I also wonder if me not running the bike with any lights on helped finish it off. The lights fitted are led's, so do these require a greater output and tie in with the 3 phase alternator I have? Genuine Lucas 47266 Three Phase Triple Pack Zener Diode Triumph T140/TR7 1981-83 | eBay

Damaged red wire
If this wire is the Boyer-Bransden Transistor Box Red wire, or is connected to it, as on the Box label, it's +ve; the other end of the wire on the LHS coil is connected specifically to the coil's "+" terminal?
The damaged red wire runs to the LHS coil "+" terminal and is 'joined' to the Transistor Box red wire at the double bullet connector shown in the 4th of my original photos (sorry, haven't worked out to do the attach link for the photos yet). Not sure how to explain the blob of metal on that wire but it was stuck to the outer part of the diode, the bit that I assume is insulated from the central part incorporating the spade connector. The wire appears to have been melted locally at this point so some copper may have been exposed - that said, I can't see any, but.............??

Wiring in a reg./rec. doesn't seem too bad having read your reply and I may well have suitable connectors, but I'll need to re-read what you've said and come back to that, probably tomorrow. I will also try and see what that capacitor is connected to - at the moment I know the black lead to it runs to the battery's negative terminal but I'm not sure where the white/yellow goes.

However, then we return to the brickbats ... '79-on models grouped a different (4-position) ignition switch and the idiot lamps in a console usually mounted between speedo. 'n' tacho. (which also had different mountings). Otoh, your bike has the correct-for-'78 2-position (on/off) ignition switch mounted in the correct-for-'78 position ... So the wirer has bodged a connection between the end of the Brown/Blue wire and one of the wires to an ignition switch terminal View attachment 793610 - educated guesses again say the Purple/Yellow wire, the connection to the Brown/Blue is inside the headlamp shell?

Standard 'negative earth' wiring with Boyer-Bransden EI, the White/Yellow wire should be between the "ENGINE STOP" switch View attachment 793611 and the same ignition coil "+" terminal as the B-B Red wire.

. '79-on had four idiot lamps - Blue main-beam warning, Amber indicators warning, Green neutral indicator, Red oil pressure warning. However, while a '79-on wiring loom will have the Slate (Grey) wire that connected the Green idiot lamp to the neutral switch, unless your bike's engine has '79-on cases with a '78 engine number stamped on 'em, the gearbox casing won't have anywhere to fit the neutral switch; if your bike has pre-'79 cases, no idea why the wirer drilled a fourth idiot lamp hole and filled it. :confused:
As far as the lamps in the headlight shell are concerned, the two green ones are for the indicators, red I'm assuming is from the oil pressure switch, and blue is for main beam. No neutral indicator which I'm not really bothered about. As far as the engine stop switch is concerned, it doesn't do anything and, I'm presuming, is not connected to anything - not ideal.

Thanks again, I'll have a re-read and anothe look at things tomorrow.
Graham
 

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My cheapo Chinese reg/rec, as seen above, drains 0.8 milliamp from the battery while the bike is parked. I measured it ten minutes ago.

Check my working, but I think that will take 52 days to consume 1 amp hour of battery capacity. If I parked the bike for months, I’d take a lead off the battery. The leads are only on spade connectors.

Wiring it for the key switch to isolate the reg/rec from the battery and then fitting relays to isolate the charging system from the ignition is not sensible, unless your reg/rec has a much greater parasitic current drain than mine.
I don't remember what the leakage draw was on my Pod. It was installed on a 68 Honda 305 Scrambler. Rode it in May and when I went to ride it in April, battery was dead. It came back with a charge, but sure did not do anything for battery life leaving it discharged that long. Took the Pod out and went back to the old system where the battery is the regulator. That worked fine with the exception that running wide open all day for multiple days pretty much boils the battery dry. So, I put the Pod back in with a relay and never looked back.

I don't doubt your calcs. But my empirical data tells me I took the correct path, at least for this bike, and this POD.
 

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I don't remember what the leakage draw was on my Pod. It was installed on a 68 Honda 305 Scrambler. Rode it in May and when I went to ride it in April, battery was dead. It came back with a charge, but sure did not do anything for battery life leaving it discharged that long.
Parking the bike from May until April of the following year can destroy a battery even if there’s no current drain. It has to be maintained with a charger.
 

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Parking the bike from May until April of the following year can destroy a battery even if there’s no current drain. It has to be maintained with a charger.
Yes, you are 100% correct. April should have read September. Not sure where April came from. I touch-type and sometimes I think my fingers are awake while my mind is asleep.
 

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Hi Graham,
pretty confident the bike is negative earth.
(y)

Zener
zeners advertised as negative earth on ebay the other day, this one (now sold) for eg, Genuine Lucas 49589 Zener Diode Negative Earth for Triumph/BSA/ Norton | eBay, though I assume that what looks like a + sign on it doesn't refer to the earthing.
Uh-uh, what looks like a + sign has a triangle underneath:-

... symbol for a diode.

would a Zener of this type have been used on a bike with a three phase alternator
As standard, '79-on non-electric start twins were fitted with the 'low output' 3-phase stator (47252), rated by original Lucas the same 10.5A @ 5,000 rpm as the single-phase 47205 stator it replaced; original Lucas rated a single Zener for 12.5A.

When the Co-op fitted the high-output 3-phase stator (47244) to electric-start twins, original Lucas deemed more than one Zener was necessary; had the Co-op continued with Zener connected across the battery, they'd have had to fit two - e.g. that's what my T160's with high-output 3-phase have (because their electrics are still 'positive earth').

The snag with multiple Zeners connected across the battery is they have to be in parallel and 'matched' for switching characteristics and, if one fails, all have to be replaced by another 'matched' set. (n)

However, if multiple Zeners are connected between each stator AC wire and 'earth', they don't have to be 'matched'; (y) the "Triple Pack" was connected to the AC wires between the stator and the rectifier. Aside, reason I can't use "Triple Packs" on my T160's is the component is specifically 'negative earth'.

and/or in conjunction with electronic ignition
Zener connected across the battery just regulates DC Volts and Amps, limiting the stator's more-variable AC Volts and turning any excess Amps generated into heat. EI wasn't fitted as standard 'til '79 but aftermarket EI (including the Lucas Rita fitted OE '79-on) had been available and fitted since the early 1970's; aside again, both my T160's have aftermarket Lucas Ritas.

reason for asking is that I also saw this one for '81-'83 bikes which specifically says its for 3 phase.
Mmmm ... it's "3 phase" because original Lucas supplied 'em to connect one Zener to each phase/wire of a 3-phase stator. However (apart from 'earth'), nothing to stop anyone connecting just two of the Zeners to the two wires of a single-phase stator - Commandos fitted with the RM23 high-output single-phase had a Zener connected to each stator AC wire, between stator 'n' rectifier. That said, they also had a weird half-wave rectifier that didn't earth through its mounting, so maybe we're wandering too far ... :cool:

wonder if the Zener I had wasn't up to the job in the first place - I also wonder if me not running the bike with any lights on helped finish it off. The lights fitted are led's, so do these require a greater output and tie in with the 3 phase alternator I have?
Working backwards through the above quote:-

. Far from it, LED are touted for these old heaps because they require less of the usually-feeble alternator output but produce more actual light than standard incandescent bulbs. (y)

. If the Zener had been mounted correctly - possibly bare-metal contact with the frame if the surrounding tubes provided the 25 square inches necessary for heat radiation - even if the 3-phase on your bike turns out to be high-output, single Zener is "up to the job" - although the 12.5A Zener rating is notionally less than the high-output 3-phase 14.5A @ 5,000 rpm rating, the Zener only has to turn excess generated Amps into heat; by definition, running engine, the ignition coils draw ~3.5A so, even if you were maintaining 90+ mph no lamps on for a long period (T140 :cool:), single Zener shouldn't have a problem.

Wiring in a reg./rec. doesn't seem too bad
(y)

The damaged red wire runs to the LHS coil "+" terminal and is 'joined' to the Transistor Box red wire at the double bullet connector shown in the 4th of my original photos
the blob of metal on that wire but it was stuck to the outer part of the diode, the bit that I assume is insulated from the central part incorporating the spade connector. The wire appears to have been melted locally at this point so some copper may have been exposed
View attachment 793543 (click on the link and the photo. will display in another browser tab).

I'm assuming there are actually two double bullet connectors in the photo. - one connecting two harness Black wires and the B-B Transistor Box White wire; the second connecting two Red wires and two White/Yellow wires? If yes:-

. While it's piss-poor, it's usable; immediate problems sorted, I can suggest how the connections can be done better?

. Conductor of the damaged Red wire touching "the outer part of the diode" would've been a short-circuit - that part of the Zener is -ve, the Transistor Box Red wire is +ve.

. Otoh, just the insulation of the damaged Red wire touching the outer part of the diode, the insulation's just been damaged by heat.

I'd just replace the damaged wire. :cool:

Capacitor
I know the black lead to it runs to the battery's negative terminal but I'm not sure where the white/yellow goes.
If the Black wire's connected to battery -ve, the White/Yellow should somehow be connected to battery +ve (although that'd be yet another piss-poor bit ...).

Older Britbikes either intended to run without a battery or with a battery but also with one of Lucas's more-feeble alternators were/could be fitted with a capacitor, to provide enough charge to start the engine. Capacitor must be connected between the -ve and +ve parts of the DC wiring - across the battery, in parallel with the rectifier.

3-phase alternator, capacitor's as much use as chocolate fireguard:-

. if the battery's flat and if the bike hasn't been left unused for months without disconnecting the battery, something electrically-serious has happened, the last thing required is some idiot starting the engine without finding out what the actual electrical problem is;

. when (not if) the capacitor goes wrong, it'll flatten the battery ...

Lamps in the headlight shell
the two green ones are for the indicators
LED, that makes some sort of sense - as a general rule, diodes only allow current to pass in one direction, whereas the single incandescent indicator warning lamp passes current in either direction, using the wiring of the 'side' not flashing to earth the warning bulb. However, not only are there 'clever' LED that allow current to pass in both directions, indicators being used only intermittently (and 3-phase alternator), LED indicators are an expensive and complicated solution in search of a problem.

No neutral indicator which I'm not really bothered about
... and, as I say, '78 cases, no place for the switch

Engine stop switch
doesn't do anything
presuming, is not connected to anything - not ideal.
Something to investigate at some stage? Switch has White and White/Yellow wires, '79-on harness will have same to connect. The only reason the wirer might not have connected is the switch and harness connectors were different - to my certain knowledge, between '79 and closing, the Co-op tried/Lucas supplied at least three different connector types ... :rolleyes:

If you ever go to dismantle the switch, do it very carefully and inside something (I use a large clear plastic bag), reason is the moving switch block contains a small ball and spring just waiting to launch into another space/time continuum ...

haven't worked out to do the attach link for the photos yet
You can attach it same as you did in your first post.

Or you can copy it from your first post exactly the same as copying some text.

Hth.

Regards,
 

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Discussion Starter · #20 ·
Once again, many thanks, Stuart.

. Far from it, LED are touted for these old heaps because they require less of the usually-feeble alternator output and produce more actual light than standard incandescent bulbs. (y)
Of course, I should have realised that from the use of LED's elsewhere.

I'm assuming there are actually two double bullet connectors in the photo. - one connecting two harness Black wires and the B-B Transistor Box White wire; the second connecting two Red wires and two White/Yellow wires? If yes:-

. While it's piss-poor, it's usable; immediate problems sorted, I can suggest how the connections can be done better?
You're right, there are two double bullet connectors and they are connected as you say - you can see this a little bit better in the pic below. I would also be interested to learn how the connections could be done better.

Motor vehicle Automotive lighting Electrical wiring Gas Auto part



Capacitor
If the Black wire's connected to battery -ve, the White/Yellow should somehow be connected to battery +ve (although that'd be yet another piss-poor bit ...).
A continuity test shows that the White/Yellow wire at the capacitor is the other end of, or is otherwise connected to, one of the two White/Yellow wires shown in the double bullet above. These are connected to the red +ve wires that run to the Transistor Box and coil.

Zener

Uh-uh, what looks like a + sign has a triangle underneath:-

... symbol for a diode.
Interesting, thanks, I'll remember that one.

Engine stop switch
Something to investigate at some stage?

If you ever go to dismantle the switch, do it very carefully and inside something (I use a large clear plastic bag), reason is the moving switch block contains a small ball and spring just waiting to launch into another space/time continuum ...
I'll have a look at this over the winter.............I do wonder if the ball and spring is already missing as the switch doesn't feel very positive to me, but I'm not sure what these switches should feel like. I had the other type on my previous, all original, 1978 T140V (owned for around 20 years but sold, regrettably, around 20 years ago).

Thanks again,
Graham
 
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