[Diy_efi] WB testing problems MORE!!!

bcroe at juno.com bcroe at juno.com
Tue Apr 23 06:28:49 GMT 2002


Steve, 

The board would probably work with the cap out or a 
smaller value.  

I'm sorry if not clear before, any electrolytic capacitor is
going to have leakage.  Tantalum too, just less.  But a 
paper/film cap should have negligible leakage.  Such 
caps are common up to 0.1 ufd, I'd try something like 
that to see if the problem is cured.  If the 0.1 causes 
a shift in voltage, its an indication there is some 
AC voltage present which takes a scope to read.

Values up to .47 ufd or 1 ufd are less common but 
available.  Putting several of these in parallel to get 1 
or 2 ufd should be adequate for the job.  

I never saw a non polarized electrolytic that small, are 
you sure?

Bruce Roe

On Mon, 22 Apr 2002 21:14:37 -0400 Stephen Andersen
<SAndersen at advan-tek.com> writes:
> Just replaced C12 with a 2.2ufd non-polarized electrolytic
> tonight and it had NO effect.  
> 
> I have not tried to alter R38 yet, but I dunno what to 
> do.  I need to get this thing working!!!
> 
> Any more ideas?  Should I try the tantalum caps
> or something else?  Voltage is near ideal with the 
> cap out of the circuit.
> 
> Someone help me get the smoke back into the wires!!!
> 
> Steve
> 
> > -----Original Message-----
> > From: diy_efi-admin at diy-efi.org 
> [mailto:diy_efi-admin at diy-efi.org]On
> > Behalf Of bcroe at juno.com
> > Sent: Saturday, April 20, 2002 4:02 AM
> > To: Stephen Andersen; bcroe at juno.com
> > Cc: diy_efi at diy-efi.org; RRauscher at nni.com; bcroe at juno.com
> > Subject: [Diy_efi] WB testing problems
> > 
> > 
> > Since the source of the problem is C12 leakage, you 
> > could get rid of the leakage.  First make sure C12 is 
> > correctly polarized in the circuit.  You could get a more 
> > expensive tantalum cap of about that value.  To eliminate
> > the leakage completely get some non polarized caps.
> > 2 or 3 caps in parallel of 1 ufd each should do it.
> > 
> > Bruce Roe

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