[TenTec] power went out

[John Molenda]

On 8/22/2011 6:13 PM, Stuart Rohre wrote:
> Certainly glad to expand on the check of fuses or switches.  It is a
> continuity check. Your ohm meter instructions should cover that.
>
> But, in general, you check on the lowest ohms range of a DVM, or DMM
> properly, or VOM.  All these meters typically have an ohms range and
> better meters have several.  You want the lowest range to force some
> current through the fuses and see if the connections are near zero ohms.
>    Expect even shorted test leads to have some resistance say 0.9 ohm, is
> typical.  Some meters allow adjusting that out.
>
> But, you apply one probe to one end of the fuse and the other probe to
> the other end.  It should read a very low value like 1 ohm.  Both should
> read the same if good.  If bad, the fuses will most likely read infinite
> resistance ie full scale or open circuit.
>
> Testing a DC power bus from positive to negative, (ground), would also
> be a case of looking for whatever resistance the output bleeder resistor
> is across the DC bus, and not an open circuit, of infinity.
> You have to have had the DC supply turned off long enough (some minutes)
> to let the charges bleed off normally from the capacitors.
>
> Don't ever measure ohms in an active circuit!  It can burn out VOMs, and
> may not be good on digital meters.  See your specific manual on your
> meter as to what is permitted.
>
> Be sure to unplug equipment from power lines before testing with meters.
>
> A switch should when closed (on), be no more than the 0.9 ohms or so, of
> the shorted two test probes alone.  At worst a few tenths of ohms.  Best
> is to compare a suspect switch to a similar on off switch.  You may find
> a similar switch on another equipment or from spares in your junk box.
> Another reason to make up a junk box, to have spare or known good
> components for comparison to tests on suspect components of the same type.
>
> For learning more about testing, see the books by John Lenk.  He has a
> whole series on electronics repair.
>
> Good Luck!
> Stuart Rohre
> K5KVH
>
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Thanks for taking the time to help out it is appreciated . John Molenda 
kb2huk