[Diy_efi] Re: looking for help with a prom N82S181

David Cooley n5xmt at bellsouth.net
Wed Nov 10 17:21:13 GMT 2004


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never seen an Ohmmeter that delivered unlimited current...=0D
Most modern DVM's have a standard ohms setting which supplies minimal
current (micro-amps) and a "diode" setting that supplies 3V or so to ensu=
re
diode junctions are biased on for testing...  I have been playing with TT=
L,
CMOS and discrete devices for 30 years and never has anything been damage=
d
by measuring in a circuit with an ohmmeter... =0D
 =0D
-------Original Message-------=0D
 =0D
From: Phil Hunter=0D
Date: 11/10/04 12:12:20=0D
To: diy_efi at diy-efi.org=0D
Subject: [Diy_efi] Re: looking for help with a prom N82S181=0D
 =0D
(Ludis Langens wrote:)=0D
 =0D
> My instructions to Marcello are:  Pull out an ohm meter.  Find what pin=
s..
=0D
 =0D
NO!!! This is a good way to destroy ICs. Ohm meters have a voltage across=
=0D
the leads, this voltage can turn on internal diode junctions and the=0D
resulting "unlimited" current can destory devices anywhere along the trac=
e.=0D
 =0D
rgds,=0D
philh=0D
 =0D
_______________________________________________=0D
diy_efi mailing list=0D
diy_efi at diy-efi.org=0D
http://lists.diy-efi.org/mailman/listinfo/diy_efi
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<DIV>never seen an Ohmmeter that delivered unlimited current...</DIV>
<DIV>Most modern DVM's have a standard ohms setting which supplies minima=
l current (micro-amps) and a "diode" setting that supplies 3V or so to en=
sure diode junctions are biased on for testing...&nbsp; I have been playi=
ng with TTL, CMOS and discrete devices for 30 years and never has anythin=
g been damaged by measuring in a circuit with an ohmmeter...&nbsp;</DIV>
<DIV>&nbsp;</DIV>
<DIV id=3DIncrediOriginalMessage><I>-------Original Message-------</I></D=
IV>
<DIV>&nbsp;</DIV>
<DIV id=3Dreceivestrings>
<DIV dir=3Dltr style=3D"FONT-SIZE: 11pt"><I><B>From:</B></I> <A href=3D"m=
ailto:diy-efi-d at t-n-e.com">Phil Hunter</A></DIV>
<DIV dir=3Dltr style=3D"FONT-SIZE: 11pt"><I><B>Date:</B></I> 11/10/04 12:=
12:20</DIV>
<DIV dir=3Dltr style=3D"FONT-SIZE: 11pt"><I><B>To:</B></I> <A href=3D"mai=
lto:diy_efi at diy-efi.org">diy_efi at diy-efi.org</A></DIV>
<DIV dir=3Dltr style=3D"FONT-SIZE: 11pt"><I><B>Subject:</B></I> [Diy_efi]=
 Re: looking for help with a prom N82S181</DIV></DIV>
<DIV>&nbsp;</DIV>
<DIV>(Ludis Langens wrote:)</DIV>
<DIV>&nbsp;</DIV>
<DIV>&gt; My instructions to Marcello are:&nbsp;&nbsp;Pull out an ohm met=
er.&nbsp;&nbsp;Find what pins...</DIV>
<DIV>&nbsp;</DIV>
<DIV>NO!!! This is a good way to destroy ICs. Ohm meters have a voltage a=
cross</DIV>
<DIV>the leads, this voltage can turn on internal diode junctions and the=
</DIV>
<DIV>resulting "unlimited" current can destory devices anywhere along the=
 trace.</DIV>
<DIV>&nbsp;</DIV>
<DIV>rgds,</DIV>
<DIV>philh</DIV>
<DIV>&nbsp;</DIV>
<DIV>_______________________________________________</DIV>
<DIV>diy_efi mailing list</DIV>
<DIV><A href=3D"mailto:diy_efi at diy-efi.org">diy_efi at diy-efi.org</A></DIV>
<DIV><A href=3D"http://lists.diy-efi.org/mailman/listinfo/diy_efi">http:/=
/lists.diy-efi.org/mailman/listinfo/diy_efi</A></DIV></TD></TR>
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