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Crumbtrail TV Forums: TV Equipment: TV Repair Forum:
Testing carbon resistor.

 

 


yorled
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Feb 15, 2011, 1:45 AM

Post #1 of 3 (1097 views)
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Testing carbon resistor. Can't Post

  I have a new resistor which is out of circuit (on the bench) and out of curiosity I measured this resistor;colour code is as follows: 1st band is red while 2nd and 3rd is black and 4th band is gold.

I use two different analog multimeter to measure its ohmic value and the readings are as follows;
1st reading which is 19 ohms came from a NIPPON AMERICA meter,ST385 with the dial set at X1 ohms range/scale.
The 2nd reading which 0 ohms came from the other meter,YX-360 TRB,with the dial also set a X1 ohms range/scale.
N.B. (1) The ohmic value of this resistor should be 20 ohms
(2) With both meters range set at X10 the reading were 2 ohms x 10 = 20 ohms.

I would like to know why the readings are differ at the X1 ohms scale.
Does one have to shorts the meter lead at 0 ohms when checking for ohmic values regardless of which ohmic range the meter set on?



tmoney45
New User

Feb 15, 2011, 2:35 AM

Post #2 of 3 (1092 views)
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Re: [yorled] Testing carbon resistor. [In reply to] Can't Post

Hello Yorled,
Based on the color bands, it's a 20 ohm +/- 5% resistor. Red Blk = 20 and the next blk= zero (no) zeros afterwards. Gold = +/- 5% tolerance. Yes, you must short the probes and zero the ohmmeter seperately for each scale. If you try zeroing it on one scale, I'm sure you'll see that it needs to be zeroed on another scale. It's usually quite evident. Also, at low resistance readings like this, the leads become a significant part of the reading and how well you make contact with the resistor will have an effect.


yorled
User

Feb 15, 2011, 11:33 AM

Post #3 of 3 (1084 views)
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Re: [yorled] Testing carbon resistor. [In reply to] Can't Post

Hello tmoney,
Thanks for the info, that was more than a mouthful.

 
 
 


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