1 megohm resistors that only measure 400-500K ohm- should they be replaced ?

[DeserTBob's Futile Efforts]

how critical is it, that resistors of 1 megohm value markings, measure
that value

I have an old R2R set that all the resistors measure OK in, except for
(2) of the 1M-ohm values

can a small Fluke digital multimeter measure that high a resistance
accurately, with the 9v battery inside ?

 

[redbelly]

how critical is it, that resistors of 1 megohm value markings, measure
that value

I have an old R2R set that all the resistors measure OK in, except for
(2) of the 1M-ohm values

can a small Fluke digital multimeter measure that high a resistance
accurately, with the 9v battery inside ?

It depends on the application, but your reading could easily be off if
you're measuring the resistors without removing them from the
circuit. The circuit could have a parallel resistance that brings the
measured value down lower.

Most DVM's worth anything can measure over 1M-ohm, and most Fluke
DVM's are worth something. And if it couldn't measure 1M, the display
would indicate an open circuit, rather than report a value that is
incorrect.

You would need to remove the resistors from the circuit in order to
get a meaningful measurement. And, for a dollar you could get some 1M
resistors from Radio Shack (if you're in the USA) if it turns out you
need to replace them.

Regards,

Mark

p.s. this would have been more appropriate for sci.electronics.basics

 

[John Larkin]

how critical is it, that resistors of 1 megohm value markings, measure
that value

I have an old R2R set that all the resistors measure OK in, except for
(2) of the 1M-ohm values

can a small Fluke digital multimeter measure that high a resistance
accurately, with the 9v battery inside ?

If you mean an R:2R DAC network, the LSB-end resistors are sometimes
half the normal values.

John

 

[JeffM]

(was: 1 megohm resistors that only measure 400-500K ohm- should they
be replaced ?)

how critical is it[...]

If he gets this unit fixed, it will appear as SPAM on these groups.
http://groups.google.com/group/sci....er-businesses+qq+Charles.M.Nudo.Jr+*-catalina
news:[email protected]

 

[Peter Bennett]

how critical is it, that resistors of 1 megohm value markings, measure
that value

I have an old R2R set that all the resistors measure OK in, except for
(2) of the 1M-ohm values

can a small Fluke digital multimeter measure that high a resistance
accurately, with the 9v battery inside ?

Yes - no problem.

However, when measuring high value resistors be sure that your body is
not part of the circuit being measured. If you use your fingers to
hold the resistor leads against the probe tips, your body resistance
will be enough to bring the indicated value down from 1 meg to 500 K
or less.

If you are measuring the component while it is soldered into a board,
there maybe other components in parallel with it that cause a
lower-than-expected reading.


--
Peter Bennett, VE7CEI
peterbb4 (at) interchange.ubc.ca
new newsgroup users info : http://vancouver-webpages.com/nnq
GPS and NMEA info: http://vancouver-webpages.com/peter
Vancouver Power Squadron: http://vancouver.powersquadron.ca

 

[ChairmanOfTheBored]

Yes - no problem.

However, when measuring high value resistors be sure that your body is
not part of the circuit being measured. If you use your fingers to
hold the resistor leads against the probe tips, your body resistance
will be enough to bring the indicated value down from 1 meg to 500 K
or less.

If you are measuring the component while it is soldered into a board,
there maybe other components in parallel with it that cause a
lower-than-expected reading.

Good call. Even "coffee breath" is enough to alter high value
resistors. Especially at higher voltage excitations.

 

[DeserTBoB]

how critical is it, that resistors of 1 megohm value markings, measure
that value

I have an old R2R set that all the resistors measure OK in, except for
(2) of the 1M-ohm values

can a small Fluke digital multimeter measure that high a resistance
accurately, with the 9v battery inside ? <snip>

Don't help this eBay con artist and spammer, Charles M. Nudo, Jr., of
Drums, PA, "66-catalina" on eBay. He is one of the worst eBay
spammers ever to hit Usenet via Google Groups, which has already
banned 28 of his accounts for spamming, threats of violence, divulging
personal information and the like.

Take his spam-gram, copy including header, and forward to his ISP,
Frontier.net, adding "SPAM FROM YOUR SUBSCRIBER" to the fwd title, to:

[email protected]

Also, cc:

[email protected]

So far, 28 of his Google Groups accounts, as well as two of his AIOE
accounts, have been terminated for spam. Let's clean him out for
good!

 

[Robert Baer]

how critical is it, that resistors of 1 megohm value markings, measure
that value

I have an old R2R set that all the resistors measure OK in, except for
(2) of the 1M-ohm values

can a small Fluke digital multimeter measure that high a resistance
accurately, with the 9v battery inside ?

Up to 100 Megs, with 1% (as a guess without knowing model and/or
specs) accuracy.
Are you sure that other resistors are *not* in parallel with the
"suspect" resistors?

 

[The Real Andy]

(was: 1 megohm resistors that only measure 400-500K ohm- should they
be replaced ?)

how critical is it[...]

If he gets this unit fixed, it will appear as SPAM on these groups.
http://groups.google.com/group/sci....er-businesses+qq+Charles.M.Nudo.Jr+*-catalina
news:[email protected]

I never see the spammers, but I always see your spam reply.


plonk....

 

[JeffM]

(was: 1 megohm resistors that only measure 400-500K ohm-
should they be replaced ?)

how critical is it[...]

If he gets this unit fixed, it will appear as SPAM on these groups.
http://groups.google.com/group/sci....er-businesses+qq+Charles.M.Nudo.Jr+*-catalina

I never see the spammers, but I always see your spam reply.

plonk....

Seems like you're all mouth and no action.

....or are you just incompetent?
There a lot of people that don't want to see spam-related stuff.
THEY configure their newsreaders as such
and I make it easy for them to weed out this stuff.

Too bad you only have half a brain.

 

[DeserTBob's Futile Efforts]

(was: 1 megohm resistors that only measure 400-500K ohm- should they
be replaced ?)

how critical is it[...]

If he gets this unit fixed, it will appear as SPAM on these groups.
http://groups.google.com/group/sci.electronics.repair/browse_frm/thre...
news:[email protected]

I never see the spammers, but I always see your spam reply.

plonk....

good post- DeserTBob has established himself as the urinal piss-bubble
foam of Usenet, killfile is the remedy for him