Sachse went bang

[graeme]

I've had a Sachse on my RT for about 4000 kms and it has been very good.
Last week during a ride the engine stopped and I found the black box had blown apart.
Any clues as to what might have caused this?
The RT has a scrambler alternater and SS regulator, 12 volt battery etc.
Coil is a Kawasaki 3 ohm and checks out ok.
The battery is a little low at just under 12 volts.

I would like to buy another black box but I would like to know why this one went bang and the smoke escaped?

Graeme

[CaptonZap]

I'm not familiar with the box you are talking about, but I am familiar with electronics.
Generally, the only component that has enough force, when it self destructs, to blow the box apart is an electrolytic capacitor. And most likely, if you look inside the box, it will be apparent what went poof. If there is a moist oily substance inside, that is almost certainly the capacitor that went.
Depending on what type of cap it was, reverse polarity will blow them. An internal short and high current will do the same. Find a HAM radio guy who is into the electronics, and he will probably be able to tell you what went by looking at it, but not necessarily why it went. Check all the external parameters. Battery voltage, regulated voltage, polarity, proper resistance of coils, no shorted wires, etc.
Sorry I can't be more definitive, but a lot of electronic trouble shooting is visual.

CZ

[graeme]

Hello Captain,

It's definitely a capacitor that went bang, I'll try and post some pictures.
I have sent an email and pictures to Sachse but as yet no reply.
I'd have to buy a new box from Sachse to get the RT going so I can test the reg but I'm hesitant to spend near $300 with the chance to blow another one if I can't find out what caused the smoke to escape.
Wiring, connectors, battery, and coil all look and test ok.

Graeme

[graeme]

first pic shown the force to lift the top and bottom of the box, next 2 pictures are with the lid removed.

[motoital]

My best guess would be some sort of electrical feedback caused the e-cap to vent. The ZDG3 instalation manual leaves a lot to be desired in my book. Did you use a fuse on the power supply? Also the ground can be critical.

[graeme]

Yes 10 amp blade type fuse.
I had fitted an Acewell tach / speedo and had strange tacho readings so I earthed the engine, frame and Sachse directly to the battery when the bike was first built.
So yes all is grounded to the battery directly.

Thank you for your suggestions.

Graeme

[motoital]

Yeah Tach signals can be iffy. Have you thought about putting a diode on the Tach signal? https://en.m.wikipedia.org/wiki/1N4148_signal_diode

Have you heard back from the manufacturer yet? I am curious.

Good luck!

[ducwiz]

Greame,

what do mean with "SS regulator"? And your SCR alternator - is it a Ducati widecase type?
A blown electrolytic cap for me indicates a possible overvoltage, i. e. caused by a foul regulator.

Hans

[graeme]

Hello Hans

Regulator from a 900 SS
The 450 RT has an alternator from a wide case scrambler
I use the two yellow wires and blanked off the red wire.
It could have over volted but the small 12 volt Yuassa lead acid battery has not boiled and shows less that 12 volts.
It could have over volted for only a short time I guess ? Long enough to damage the Sachse and stop the engine but not long enough to damage the battery???
Won't know for sure until I can run the engine again.

Motoital, no haven't heard from Sachse yet

[ducwiz]

Hi Greame,

if the 900SS regulator was running with a 2-wire alternator, everything is fine. If it had been formerly used with a 3-wire stator, it is definitely the wrong type. But - no overvoltage could have occured in both versions, if the Faston connectors had a tight fit on the corresponding lugs.
If you combine a 12V regulator produced for a 3-wire alternator with your 6V-2wire system (by dismissing the red wire) you never will reach the maximum power output. The 2wire-regulator is mandatory for this.
Solid-state electronics may die very fast by an overvoltage, while lead batteries can stand this for minutes to hours (power-dependent).
It would be very interesting to refit a new capacitor and see whether the ignition circuit has survived. Did you discuss this with Sachse/Patzer?

cheers Hans