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Reggie3cl
Guest
Did your ride to work take you past a tack factory? 
DoC!
Hero member
Must have been a camera bike in the Tour de Frogs......Tacky comment I know. 
Er yes, I know, pointless effort trying to pin down the problem.
DoC!
Er yes, I know, pointless effort trying to pin down the problem.
DoC!
sonicboom500
Hero member
Sounds like a dry joint or broken wire, the initial current arcing or passing through some remaining strands
warms it up enough to expand and make a better contact.
Once it is warm it will work reliably and repeatably but once it cools down it opens up again and it's pot luck.
Usually over time the arcing erodes what little contact you have or the last strands part and it's dead.
Years of stripping R/C buggies and touring cars for intermittent faults usually ended with one of these causes.
It's impressive to see what 30 amps can do to a shorted speed controller.
Used to check the wires with a battery and a headlamp bulb with both filaments connected.
It would draw enough current to show a resistance quite clearly.
Or you could just buy some new smoke.
warms it up enough to expand and make a better contact.
Once it is warm it will work reliably and repeatably but once it cools down it opens up again and it's pot luck.
Usually over time the arcing erodes what little contact you have or the last strands part and it's dead.
Years of stripping R/C buggies and touring cars for intermittent faults usually ended with one of these causes.
It's impressive to see what 30 amps can do to a shorted speed controller.
Used to check the wires with a battery and a headlamp bulb with both filaments connected.
It would draw enough current to show a resistance quite clearly.
Or you could just buy some new smoke.
sonicboom500
Hero member
Just a PS to my last post.
You have to select a load appropriate to the wire diameter being tested.
Automotive bulbs give a fairly clear indication of the current stability and are available in enough
wattages to give cheap loads.
The twin filament headlamp bulb was for motor wires and cycling nicads.
I had a strip of bulb holders with different wattages and connected the combination that gave the required load.
You have to select a load appropriate to the wire diameter being tested.
Automotive bulbs give a fairly clear indication of the current stability and are available in enough
wattages to give cheap loads.
The twin filament headlamp bulb was for motor wires and cycling nicads.
I had a strip of bulb holders with different wattages and connected the combination that gave the required load.
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Reggie3cl
Guest
Hmm, well that certainly sounds like the symptoms I've got. That said, I still had no go even with the unit definitely getting power as indicated by a bulb and the coil positive feed jumped directly from the battery. Suppose there could be a problem with the wiring from the trigger, but of course that's all new.
I would have thought that a 21W indicator bulb would show up any problems- the unit must draw a fraction of what that does.
I would have thought that a 21W indicator bulb would show up any problems- the unit must draw a fraction of what that does.
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Reggie3cl
Guest
Already have bypassed the unit and rigged up a separate feed for the coils to no effect.
Am going to try the circuit with a headlamp bulb to see if there is anything up as Kevin suggested, but certainly no amount of wiggling and pulling wires has shown up anything thus far.
It's so dead when it doesn't work maybe there is something wrong with a wire from the trigger, I dunno.
These things make me really grouchy (especially as quality shed time is at a premium right now) as unlike some I can't stand not having my bike ready and able to go when it's supposed to be. Chucking it in the back of the garage and using the GS is not an option.
Am going to try the circuit with a headlamp bulb to see if there is anything up as Kevin suggested, but certainly no amount of wiggling and pulling wires has shown up anything thus far.
It's so dead when it doesn't work maybe there is something wrong with a wire from the trigger, I dunno.
These things make me really grouchy (especially as quality shed time is at a premium right now) as unlike some I can't stand not having my bike ready and able to go when it's supposed to be. Chucking it in the back of the garage and using the GS is not an option.
andrew112_uk
Senior member
If you have taken a direct feed to the coils then it rules out a dis' in the ignition circuit ( No expert here but I had a similar infuriating problem and still have the "hot wire" under the seat from my investigations) and a short circuit would presumably blow a fuse.
Sooooo, is anything wrong with the connector on the DMC box? ( my problem was the plug being pressed sideways by the side panel) How is the earth to the box?
Just my humble thoughts... I know how infuriating it can be
Andrew
Sooooo, is anything wrong with the connector on the DMC box? ( my problem was the plug being pressed sideways by the side panel) How is the earth to the box?
Just my humble thoughts... I know how infuriating it can be
Andrew
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Reggie3cl
Guest
Hey, all musings welcome!
Have an earth for the unit to the frame and then a direct wire straight to negative on the battery just to be on the safe side.
Think the plug is OK but will check again.
One of the disadvantages of living up here is that I only know one person with a Laverda, which may have a Witt (I'm not sure) which I'm sure he'd lend to me, but his bike is a twin... :
Have an earth for the unit to the frame and then a direct wire straight to negative on the battery just to be on the safe side.
Think the plug is OK but will check again.
One of the disadvantages of living up here is that I only know one person with a Laverda, which may have a Witt (I'm not sure) which I'm sure he'd lend to me, but his bike is a twin... :
DoC!
Hero member
Keith Nairn could drive up there in a couple of hours - or you could borrow a trailer and take it down to Glasgow.
Of course that costs in time and money, and more than not it is something very simple that only time will find.
Have you checked the fuses or if there is a bad connection on the fuses?
DoC!
Of course that costs in time and money, and more than not it is something very simple that only time will find.
Have you checked the fuses or if there is a bad connection on the fuses?
DoC!
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Reggie3cl
Guest
Well, now here's a thing; I had to disconnect the box to warm it gently last time, and it did work again afterwards.
I took the box off yesterday so I could get at the switch without disconnecting it. It wouldn't fire, so I removed the box completely ready to send off for testing. Then to check something else I reconnected it and it fired fine.
Just checked it again after standing overnight and it's fine
Did this all start when I took the unit off cos the bracket had broken???
Could be a duff connection at the plug- power shows coming through at the terminal when testing the plug, but maybe the terminal inside the plug is damaged and not making a decent connection with the box?
I took the box off yesterday so I could get at the switch without disconnecting it. It wouldn't fire, so I removed the box completely ready to send off for testing. Then to check something else I reconnected it and it fired fine.
Just checked it again after standing overnight and it's fine
Did this all start when I took the unit off cos the bracket had broken???
Could be a duff connection at the plug- power shows coming through at the terminal when testing the plug, but maybe the terminal inside the plug is damaged and not making a decent connection with the box?
lawrence
Hero member
- Location
- Idaho, USA
Be alert for melted fuse holders
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Reggie3cl
Guest
Dry joint (I think)
I'm the one on the right...
In my defence it all checked out, it was just Kevin's description of a problem coming and going with a dry joint that made me wonder if there was a problem with the kill switch feed connection (the connctor block has been bypassed) so I rigged up a fly lead for a direct feed to the battery to where I thought the problem might be, and it seemed to be OK. I remade the connector and no probs thus far. Will test gain in an hour or so...
I'm the one on the right...
In my defence it all checked out, it was just Kevin's description of a problem coming and going with a dry joint that made me wonder if there was a problem with the kill switch feed connection (the connctor block has been bypassed) so I rigged up a fly lead for a direct feed to the battery to where I thought the problem might be, and it seemed to be OK. I remade the connector and no probs thus far. Will test gain in an hour or so...
Attachments
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Reggie3cl
Guest
FAHN CAHN!!!
Just about to put the bodywork on, thought I'd double check all was OK- buzzing away nicely on the test cycle, about 4000 rpm or so on the tacho and then AAAARGH!!!! cut out again. Ye bastid! Without touching anything I pulled apart the connector for the positive feed which produced a decent spark at the connector and without touching anything else plugged back in the fly lead to the battery. Nothing. And then after a few seconds off it went. None of the wiring from the positive feed is old and it goes nowhere near the kill switch when the fly lead is connected.
So it wasn't a dry connection in the positive feed from the kill switch. I've promoted myself to being the slightly less dumb looking one on the left...
Just about to put the bodywork on, thought I'd double check all was OK- buzzing away nicely on the test cycle, about 4000 rpm or so on the tacho and then AAAARGH!!!! cut out again. Ye bastid! Without touching anything I pulled apart the connector for the positive feed which produced a decent spark at the connector and without touching anything else plugged back in the fly lead to the battery. Nothing. And then after a few seconds off it went. None of the wiring from the positive feed is old and it goes nowhere near the kill switch when the fly lead is connected.
So it wasn't a dry connection in the positive feed from the kill switch. I've promoted myself to being the slightly less dumb looking one on the left...
KERMIT1200
Hero member
- Location
- Worcester,UK
Have you contact Witt and explained to him the symptoms.The rumour I heard was the latest 'black boxes' were suffering/could suffer due the use of non leaded solder.How true well!how old is your Whitt?
I think its time to speak to the man him self
Andy
I think its time to speak to the man him self
Andy
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Reggie3cl
Guest
Yeah, just sent him an email. My box is a sort of bronze colour and is two years old.