Re: Europa-List: Starter Diode

[Kingsley Hurst <kingsnjan@westnet.com.au>]

Hello Dave,

I haven=99t got your previous posts in front of me but I assume you wa
nt to put the diode across the starter solenoid.  

If my assumption is correct, you should connect the anode to the starter mot
or side of the starter solenoid and the cathode to the positive (starter swi
tch) side of the solenoid. 

If you have had it connected the other way around and tried starting the eng
ine, the diode would have been forward biased trying to carry the full curre
nt of the starter motor and more than likely will be ruined. 

Either check the diode with a multi meter ( on ohms scale) to ensure it cond
ucts in one direction but not the other or use a new diode. 

When connected correctly, on pressing the starter button (or key switch), th
e diode is reverse biased and has no effect..... all the current passes thro
ugh the solenoid.  On releasing the starter button (or key switch), the coll
apsing magnetic field in the starter solenoid tries to induce a high voltage
 spike but this is swamped by the diode because the diode short circuits the
 current induced by the collapsing magnetic field in the coil. 

Hope this hasn=99t made it more confusing for you.  I could and probab
ly should have just said ..... connect it like the manual says. 

Best regards
Kingsley in Oz. 

Sent from my iPhone

> On 7 Jun 2021, at 7:17 pm, david park <dpark748@me.com> wrote:
> 
> =EF=BBAllan have you put ANODE to switch contact?
> 
> Dave Park
> 
> 
>>> On 7 Jun 2021, at 09:35, Alan Burrill <alanb@dpy01.co.uk> wrote:
>>> 
>> =EF=BBAre you sure the diode is not faulty?
>> 
>> You can check it with an meter set to read resistance. Should be high res
istance one way and low the other.
>> 
>> Have you tried connecting it the other way round?
>> 
>> Alan
>> 
>> Sent from my iPad
>> 
>>>> On 7 Jun 2021, at 09:02, david park <dpark748@me.com> wrote:
>>>> 
>>> =EF=BBBud,
>>> Still confused as Europa Manual wiring diagram shows Anode to Earth? Not
 switch.
>>> Regards
>>> Dave Park
>>> 
>>> 
>>>>> On 7 Jun 2021, at 01:06, Bud Yerly <budyerly@msn.com> wrote:
>>>>> 
>>>> =EF=BB
>>>> Dave,
>>>> I didn't see anyone commented on your diode.
>>>>  
>>>> Pretty much any diode will do.  If you get it backwards, the saving gra
ce is the start solenoid is looking for 12 volts.  Of course, the solenoid m
ust be grounded.
>>>> Most mistakes are the ground is left off the solenoid when putting on t
he diode.  Another problem is guys don=99t insulate the anode side of t
he diode and it shorts. 
>>>>  
>>>> The Rotax manual doesn't comment on the diode.  But it is an accepted p
ractice to extend the life of the contacts in the starter solenoid.  The Eur
opa Electrical Chapter  25 advises to use an IN5404 but any will do.
>>>>  
>>>> IN5404
>>>> <image001.png>
>>>> 
>>>> silicone diode is shown above.  Anode or plus side is on the starter sw
itch tab and the cathode or negative goes to the ground bolt holding on the s
tarter solenoid.  I use at least a #18 or 16 wire from the solenoid fastenin
g bolt to the main firewall ground.
>>>>  
>>>> Best Regards,
>>>> Bud Yerly
>>>>  
>>>> -----Original Message-----
>>>> From: owner-europa-list-server@matronics.com <owner-europa-list-server@
matronics.com> On Behalf Of david park
>>>> Sent: Wednesday, June 02, 2021 2:44 PM
>>>> To: europa-list@matronics.com
>>>> Subject: Europa-List: Starter Diode
>>>>  
>>>>  
>>>> I fitted a starter Diode and engine would not start. Orientation was as
 described with band end cathode on starter terminal and other end to earth?

>>>> Have I got wrong diode.
>>>> Any advice appreciated
>>>>  
>>>> Dave Park G-LDVO
>>>>  
>>>>  
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