Assimilator problem.

Hi all,Mike here,new member and long time Commando owner.
Ive had my Mk 2 850 for years and few real problems with it but it's only used part time,mostly summer riding.
My mate has just bought a 74 Mk 2 and we've been sorting bits and pieces over the past few weeks,it's only done 7 thou miles but has been sitting around a lot,however it is tidying up nicely and runs well.
Through testing we deduced the original tin can assimilator was defunct so replaced it with a new encapsulated solid state unit and the warning light went out as per schedule,however this unit failed and we thought the earth terminal may have lost its spade connector and rubbed intermittently on the stainless braided oil feed pipe causing a fault.A new replacement unit was fitted,but this too seems to have failed.At 50 pacific pesos a time we need to find out what is causing this.Surely we would not get two faulty units.They did not fail immediately but probably within miles of use.Alternator output was 24-30 volts with Stu revving approx.3.5-4 thousand revs.Have checked Zener connection and dumping voltage,seems to be OK but not 100% sure.
Has anyone had anything similar?I have checked dozens of threads in 'Search' but nothing like this.

Thanks, Mike.

Hello Mike, and welcome to the forum.

Gemini 3 said:

Through testing we deduced the original tin can assimilator was defunct so replaced it with a new encapsulated solid state unit

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Can you say exactly which type of encapsulated units they are? Or where they actually came from?

Thanks for the quick response L.A.B.
I will check on brand when I next see Stu.
There sure are a lot of enquiries on this site!
Thanks ,Mike.

If its one of the common solid state ones they don't go in place of the assimilator. Can I ask how it was wired? and as LAB says the make , type or a pic would be handy. The ones I use are about an inch square, 3 wires, 2 wires go accross the 12vDC (pick up a supply in the headlamp) and the other powers the warning light.

Gino Rondelli said:

If its one of the common solid state ones they don't go in place of the assimilator.

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I think the "Cool Cat" one is wired the same way as the original 3AW assimilator.

http://coolcatcorp.com/Merchant2/mercha ... ry_Code=EL
http://www.coolcatcorp.com/ss3aw.doc

Hi Gemini,

couldn't help notice you said "Alternator output was 24-30 volts with Stu revving approx.3.5-4 thousand revs."
Seriously 24-30 volts??

Hi David,yes the voltage is across the gn/y and gn/w leads from the alternator.This is AC volts.
Just checked my own bike and get similar,22v AC @ 2000 RPM and 32-35v AC at about 3000 RPM.
I haven't checked the make of replacement assimilator yet but it is a plastic/solid state copy of the old tin can with the same labelled connections.
From these readings I think the half wave rectifier should bring volts back to 11-16v DC and the Zener limit the volts to about 13.5v DC.
This seemed to be the case but after 3 dead ass's I wondered if anyone else had had a similar problem.
Stu's battery is fine although a bit low after a 100 mile run(with lights on),mine is the same,but I gues that's another issue.

Thanks for your help so far guys,Mike.