Multimeter giving random results

[netdudeuk]

Hi

I've just got a load of 1% 1/4 watt resistors and was comparing the bands with what my DMM was showing.  Most 'strips' are ok but some of them have resistors which are way off the mark, like fifty percent.  I've scraped the wires to get better connections and replaced the battery but things are the same.  Also, the resistance reading would be constantly changing by a small amount

Any ideas please ?

Thanks

[karlmag]

Hi,

Bad quality resistors and/or wrongly labled ones?

I know it has happened.

Guess it might depend on if it's a reputable shop and if it's brand- or noname resistors too.

[alm]

Your DMM is unlikely to give stable values that are 50% off if you connect it to some resistors but not to others. If it's consistently off for the same resistors, then I would say you've got a bad batch of resistors. You sure it's not a red band that looks brown or something silly?

I know some Chinese vendors will paint carbon film resistors blue with a brown tolerance ring and sell them as 1% metal film. Did they start relabeling 1k resistors as 2k now?

[netdudeuk]

Quick responses thanks guys.

I got them from China and they are indeed blue with a brown tolerance ring and advertised as 1% metal film.

I'm ok with the colours but I did wonder at first how you were meant to know which way round some of them were as they looked tangible either way.

Maybe I ought to check every resistor before I use it.

[tszaboo]

Oh, China, that explains a lot. I think it is probably cheaper if you buy some Welwyn, Bourns, or Vishay. Time is money.