DMC optical sensor warning!

While possible the new opto is DOA, highly unlikely. One reason you buy several new parts, in case of faulty item.

Suggest a couple of test processes that you may decide to use, or not.

In a darkened ambient light, use your phone camera to look at the unshuttered opto gap ( or unmount the opto, while still connected ) the IR led will be visible on the camera as a white light. That will confirm IR LED is functioning. This works on past phones, have no experience with modern multicamera devices.

More fiddly would be to break out the photo transistor connections and put a meter across the Emitter and collector, slow rotate the motor/shutter and look for high volts and near zero low volts, that will confirm correct slotted opto function per se.

Take it that the mechanical dimension replacement opto does fit?

Electronics repair is a game of patience and process, can be unrewarding though when repaired, very rewarding. HTH j.
 
Thanks, some things to try later....
To be honest Im seriously thinking of just changing the whole DMC thing for another ignition system, lost the whole summer trying to get this misfire/shutting off sorted.

I was in touch with Witt and they said it was highly unlikely that the box was at fault and suggested changing the opto sensor...

Il try and check out the sensor but ill let the supplier know i think its died and see what they say....

cheers

STU
 
Changed to other ignition system may provide best outcome, since you have contacted Uwe or staff, my thinking would have him test the item in question. Is your unit hard wired or later plug type? Since ( appears ) the opto is on a plug, it may be the latter, all a guess here. Part of customer service, did he suggest how you would replace the slotted opto and with what part? Wrote to Uwe in the 90's and no reply ever came my way...unfair or no, it is what it is. Then designed the iis, another story.

Have seen a notable number of intermittent and or dead DMC units over the decades, problem when servicing VTR's in the day, folk would ask me what is a good brand of VTR? How would i know, all i see is faulty ones.... sic. So it is with DMC, problem DMC(s) came to my attention and need to be measured against the supplied number or all units over the decades. Uwe was one of the first for Laverda dedicated digital ignition.

What i will say ( for DMC modules ) is "hard potting" the internal pcb was a mistake, in warmer countries, worked on DMC mounted Ducati's also. Bunch of dead DMC's here somewhere, nostalgia...perhaps, j.
 
If no sparks in test mode, then I suspect it is not the sensor. And yes I have seen the Moto Witt modules go bad. The ones on my 3CL and RGS died many years ago which is why the bikes now have a IIS ignition.

The one on my RGS, Wolfgang sent me a new one and he took the bad one back to Germany on one of his trips. Uwe Witt took it apart and said the module failed from me using ignition cols with too low of a resistance. Which was not the case, they were 3 ohm TEK coils.
 
1200ts said:
The one on my RGS, Wolfgang sent me a new one and he took the bad one back to Germany on one of his trips. Uwe Witt took it apart and said the module failed from me using ignition cols with too low of a resistance. Which was not the case, they were 3 ohm TEK coils.
Click to expand...
Ignitech box does not care what Ignition coils are being used, on street bikes I use 3 ohm Nology Pro-Fire Ignition coils but my race bikes run 3 x single output 0.6 ohm Nology Pro-Fire ignition coils, one each cylinder and never had an issue

Stu, if you have installed a new Optical sensor and still no luck with the ignition then install an Ignitech box, it will work with the Optical sensor
Just tell Ignitech you have an Optical sensor as they need to change something internally in the box to suit that signal form, their standard is for Inductive triggers which have a wave type of signal as opposed to Optical and Hall Effect which are either on or off
I use Hall Effect triggers on all my ignitions
 
Specious assertion on the DMC being de-potted and failed coil drive transistors failed, Bruce... Uwe may like to re-assess running that line past old techs. This has more to do with DMC module known characteristics than a personal matter, as such Uwe has respect overall, give or take statements of dubious origins. The latter, can do much harm, if not obvious to Uwe. j.
 
I never believed Uwe's explanation as to why the module failed. The ignition always had 3 ohm TEK coils. The module failed on a particularly hot day of over 100 degrees. I think the potting of the module was a bad idea and the internal components run too hot.

And these same "bad coils" that caused the module failure have been working perfectly with the IIS ignition for over twenty years.
 
Much is about technical acumen, USA, Germany and Australia, in this case. As we know Bruce, Drive transistor failure can be interpreted, over current usually open circuit emitter to collector as a guide ( S to D for IGBT ), over voltage or reverse impulse Voltage E-C or Source to Drain punch through, short circuit. Also Base to Collector ( Base to Drain IGBT ) punch through an indicator of what actually caused the device failure. Not that all this is of general concern here.

Found the Gen 4 devices from IR ( International Rectifier ) to be well robust and reliable, there were no unexpected device failures in the history of iis boards, through hole ( TO220 ) or SMD devices. High Grade clear conformal coating to mitigate moisture issues, module pcb and crank encoder pcb. Did by situational outcomes, have an open ended outer case format, allowing some extra cooling over a sealed outer case form.

Stu, can you confirm the Omron slotted opto is in fact a physical drop in replacement? Please, for the library records here. Confident the electrical compatibility is valid, if not superior to the oem part.
 
So the replacement sensor arrive from Texas, after fedex managed to loose it for a few days.....
All connected temporarily up and bingo sparks aplenty when the Witt is in test mode, ill get it fitted properly and see if it fixes my cutting out issue!

Stu
 
Jota996 said:
So the replacement sensor arrive from Texas, after fedex managed to loose it for a few days.....
All connected temporarily up and bingo sparks aplenty when the Witt is in test mode, ill get it fitted properly and see if it fixes my cutting out issue!

Stu
Click to expand...
If I remember correctly, with the bad sensor and in test mode, it did not spark?

With the new working sensor, if you disconnect it and put it in test mode does it spark?

I would think the ignition module would not care when in test mode whether the sensor is good, bad or even connected?
 
Similar thoughts here Bruce, though may be conditional internals for the DMC, a well thought out test invocation would have two test routines ), one for the "pickup" ie input to DMC correct and one for coil drive confirmation, as i do on the iis "E"ncoder and "F"ire all coils/plugs.

Also as the crank encoder board ( Opto and HE ) the encoder is supplied by constant current source, not Voltage, the small constant current source circuit uses a led for the Vref on the CC driver Base. When 10-20mA is being sourced the ref led lights ( decimal point on the 7 segment display iis latter ) if the encoder board is not connected the indicator led will not light. Double confirmation on the encoder board is the yellow led that signifies valid supply to encoder pcb. Given the whole encoder works on constant current there is no restriction of adding in a red smd led to each HE pickup ( also on later vesrion of the opto encoder ), that feeds the opto isolators on the main module pcb, nifty if i do say so myself.

Backgroundd for readers of this, design and fabrication of constant current makes the encoder board short or mis-wire proof, you cannot electrically damage an iis encoder board no matter any miswire or wire to frame ( worn insulation perhaps, had one encoder cable resting on an exhaust pipe one client, only misfired when hot, the insulation was not permanently melted and would self repair until the exhaust got hot next time ). Funny one that one..well maybe to me funny....j
 
Wired everything up properly and now have a running engine, sadly no chance to road test at the moment here in the uk as the roads have all turned to rivers.... :-(

If this doesnt fix it Im changing the ignition....

Stu
 
So with the advent of a fine sunny day here in North Northumberland I risked a test ride and he is back to wonderful normalness... after reg/rec tested and checked, wiring all checked, new plugs, leads, japaneses coils, the misfire is sorted. so it was the optical sensor or wiring after all.

to recap, the original opto sensor was working on test, 0 setting on the DMC box and started the bike ok
There was a an occasional misfire at higher revs when running.
A replacement opto sensor was sourced from Mauser Electronics following the advice of cleverer people than me on here...
This was fitted and proved to be DOA.
Replacement supplied and tested on the 0 setting, all ok
All fully rewired, set to 9 on the DMC etc so bingo!!

Thanks to all for the info rev the correct sensor.
If you do this make sure you check the function of each wire as the colours are different on the Mauser one at least..

cheers

Stu
 
Great news Stu. I'm chuffed you got it sorted.
A fine example of how this forum comes together for a bit of problem solving.
 
Gestalt Laverda, members scattered around the globe. There is a great deal of disappointment when a fault endures, only increases the near euphoria when you do "sort it" as the poms would say.... did well in the end Stu, for applied efforts.

All the same, as Bruce makes clear, the DMC is voltage supply susceptible, some variants may be more or less so. High and low volts known issues, what needs to be kept in mind is automotive alternator "load dump", this produces minus 50-80V spike when the ignition is turned off. Actual negative voltage spike into the 12V buss, various items like battery ( another plus for low impedance battery ) and rectifier may mitigate this known spike. Perhaps a hefty diode reverse biased across the supply to the DMC may be of some value.

12 months ago i had a remote control golf buggy take out its motor drive module multiple times, after i repaired them ( also potted, which i de-potted ) the clue was that not only the motor drive transistors had shot through, also the PWM controller chips were damaged, this is common on bipolar transistors not nearly so with IGBT. Soldered two 3amp diodes reversed biased across the battery supply connections on the PCB, no more damaged pcb from motor load dump ( the motors were hefty permanent magnet type ie similar in electrical "appearance" as the PM alternators on motorcycles ). HTH j
 
While we're at electrix i had an issue with a blown fuse on the recent club ride to Jamieson. Bike had been started and stopped several times, running faultlessly for hours. Dunny break and came out and the motor turned maybe one rev and the starter button went dead. Was a blown fuse and my guess is I'm running the starter relay off the same circuit as new hi-output coils to compliment the Ignitech - the difference going from 3ohm with old plug leads, reisitor caps and non-resistor plugs was immediately noticeable, much cleaner at very high revs. Anyways, I did a quick calc using an online calculator and if it's correct - John will confirm :cool: - 3.0ohms draws 4amps (x 2 = 8amps), 0.5ohm draws 24amps!! (x 2 = 48amps!!). Astonishing, such a huge diff. Does that mean they're drawing 48amps whenever the engine is running?? A race bike running constant loss battery would need a decent battery to cope with that.

Fitting the new coils also seemed to coincide with stripping the Gates toothed belt that drives my ND alternator - quite possibly due to the increased current draw?
 
Electrical condition of CC Constant Current or "current limited" would have the low ohmic coils at around the 3-5amp span, not privy to ignitech design parameters. Doubt what you have is down to the design values for the ignition, type a better reply later, just rgo'ed the 79 Jota nd have a club plate to fit...HTH j
 
If you are still using the original regulator, get rid of it even if it tests OK. I have spent many wasted hours trying to sort ignition problems that were caused by a "good" regulator. My RGS had a ND regulator that would not regulate properly after a few miles and had warmed up. It would test OK back home but would regulate at 15.5 volts on the road causing all kinds of problems with the Moto Witt ignition. It would misfire or just turn it self off miles from home. These days I use regulators from a Yamaha R1 that are designed for an alternator with a much higher output than our bikes have.

The newest one from Shindengen is the FH020AA but any of the ones fitted to the Yamaha R1 (and many other Japanese bikes) are OK. I usually use the FH012AA as it is the most common and get them from the breakers or Ebay. Never bought a new one. Be very careful on Ebay. Lots of fake Chinese ones that don't last. A clue is a real one has an aluminum plate on the back.
 
iis_iis said:
Electrical condition of CC Constant Current or "current limited" would have the low ohmic coils at around the 3-5amp span, not privy to ignitech design parameters. Doubt what you have is down to the design values for the ignition, type a better reply later, just rgo'ed the 79 Jota nd have a club plate to fit...HTH j
Click to expand...
The Ignitcec we use does not supply power to the coil +, just the pulse to the - side.
 
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