Re: [DML] RPM Relay - Problem Solved!

[DANIEL SHANE <daniel.shane@xxxxxxxxxxxxxx>]

Great news Dave,

but where did you get the schematic for the RPM relay
from

Dan

--- doctorDHD@xxxxxxx wrote:

> Problem: RPM Relay never shuts off after the car
> starts  even when the engine 
> dies.
>  
> Tom Niemczewski wrote me off  list and suggested I
> check out a few items in 
> the RPM Relay schematic.  I  went through a few of
> them with no luck and tried 
> experimenting to try to get to  the bottom of this
> seemingly simple problem.  
> After I tried and tried  unsuccessfully, so I
> measured all the voltages at all 
> the pins of the 555  timer.  Then I sent an email of
> to Tom with the info.  
> As I was  composing that email I reviewed the data
> that I collected and one 
> piece seemed  to stand out.  That was the fact that
> there was a constant 4 volts 
> on  the 6/7 pins of the 555.  Since it was below the
> 2/3 of the 10 volt power  
> supply it meant that the timer would be on. But this
> is a simple RC circuit  
> and thus the cap voltage should rise until it
> reaches the 10 volt  supply.  
> Something was keeping it low and thus keeping the
> timer on.  I scrutinized the 
> circuit some more and realized that either the 
> transistor across the capacitor 
> that is connected to pins 6/7 was leaky or the  cap
> itself was leaky.  Since 
> I had already replace the transistor, i  replace the
> cap and viola!  (Tom did 
> mention the cap in his original reply  to me but I
> couldn't believe it could 
> go bad.  Now I believe  it.)
>  
> I'm sorry if all this is too technical or boring for
>  some of you but is just 
> supports the fact that this group is a great bunch
> of  people that spend a 
> lot of their valuable time helping each  other.
>  
> So thanks Tom for your help on this one.  (I still 
> have that annoying tach 
> flicker but hopefully it will be solved too some 
> day.)
>  
> D² and 6530
> Dave Delman
>  
> BTW Tom was not the only one to lend a hand on this 
> one, Elvis was in there 
> too.
> 
> 
> [Non-text portions of this message have been
> removed]
> 
> 
> 
> 
> 
> To address comments privately to the moderating
> team, please address:
> moderators@xxxxxxxxxxx
> 
> For more info on the list, tech articles, cars for
> sale see www.dmcnews.com
> 
> To search the archives or view files, log in at
> http://groups.yahoo.com/group/dmcnews 
> Yahoo! Groups Links
> 
> 
>     dmcnews-unsubscribe@xxxxxxxxxxxxxxx
> 
>  
> 
> 
> 
> 





To address comments privately to the moderating team, please address:
moderators@xxxxxxxxxxx

For more info on the list, tech articles, cars for sale see www.dmcnews.com

To search the archives or view files, log in at http://groups.yahoo.com/group/dmcnews 
Yahoo! Groups Links

<*> To visit your group on the web, go to:
    http://groups.yahoo.com/group/dmcnews/

<*> To unsubscribe from this group, send an email to:
    dmcnews-unsubscribe@xxxxxxxxxxxxxxx

<*> Your use of Yahoo! Groups is subject to:
    http://docs.yahoo.com/info/terms/