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I have this resistor on a board.

Can someone can help me determine the value from the photo?

I did a ohms reading, and actually just around 22k Ohm. Which cannot be right. I asked about this in a previous post, but guess I needed a separate thread.

enter image description here

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    \$\begingroup\$ Why 22k cannot be right? \$\endgroup\$
    – Justme
    Commented Aug 10, 2020 at 17:16
  • \$\begingroup\$ SMT resistors (at least the smaller packages) do not directly specify Ohms - there's not enough room. They use some specific code that (I believe) is unique to the vendor. \$\endgroup\$
    – td127
    Commented Aug 10, 2020 at 17:17
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    \$\begingroup\$ @td127 there's a canonical coding for SMD resistors. it's two digits of mantissa, and one for the exponent. The value is mantissa · 10^(exponent) Ω. \$\endgroup\$ Commented Aug 10, 2020 at 17:26
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    \$\begingroup\$ You didn't happen to measure the resistor in the circuit, did you, mnemonic? \$\endgroup\$ Commented Aug 10, 2020 at 17:27

2 Answers 2

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SMT resistors have gotten so small, they are often now coded with a scheme that does NOT show the actual resistance value. (Not enough space to print the traditional code)

It's called the EIA-96 system.

https://www.hobby-hour.com/electronics/eia96-smd-resistors.php

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  • \$\begingroup\$ I did not know this. Thanks. \$\endgroup\$
    – mnemonic
    Commented Aug 10, 2020 at 19:30
  • \$\begingroup\$ Cool, I did not know this either (that the code was standardized). \$\endgroup\$
    – td127
    Commented Aug 10, 2020 at 21:36
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  1. You can't measure the value of a resistor with it in the circuit. You must remove it from the board.
  2. Surface mount resistors are usually marked with a 3 or 4 digit code.

For a 3 digit code, the two left digits are a number and the right most digit is the number of zeros to append to the value. 103 is the value 10 with three more zeroes appended - total value is 10000, or 10 kiloohms.

A four digit code has three value digits to the left and one digit for the number of zeroes. 1002 is 100 with 2 zeroes appended - that's 10000, or 10 kiloohms.

The code on your resistor is a little unclear.

It is a 3 digit code. The left most digit is either 6 or 8. 624 would be 620 kiloohms, 824 would be 820 kiloohms.

You'll have to take it out and measure it if you can't get a better look at the left most digit.

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  • \$\begingroup\$ @Passerby: It's a surface mount part. You can't practically disconnect one side. \$\endgroup\$
    – JRE
    Commented Aug 10, 2020 at 18:01
  • \$\begingroup\$ although looking at those indents, an attempt was made \$\endgroup\$
    – user16222
    Commented Aug 10, 2020 at 18:52
  • \$\begingroup\$ Hey guys. I am just replying to say I know exactly how the marking works on these resistors, and yes, I did measure in circuit as the rest reflected their markings correctly. I know a parallel combination of circuits can throw the expected value of, but as said I was wondering why the marking looks like that. I dont own a hot reflow system, so regular soldering and wick is what I use. Desoldering gun I have yes, with a silicone tube made on top of teflon piece to suck, but doesnt work all the time. I mean for instance a marking of 103 will mean 10K resistor. So I understand all this perfectly \$\endgroup\$
    – mnemonic
    Commented Aug 10, 2020 at 19:18
  • \$\begingroup\$ And a 0 alone marking could mean a sensing resistor. So what is the first character in there, IN CASE, its a bad resistor when I managed to lift the one side from the board at least? Or will circuit analysis be my only way to get a estimate. \$\endgroup\$
    – mnemonic
    Commented Aug 10, 2020 at 19:24
  • \$\begingroup\$ @mnemonic: How to remove a resistor without breaking it. \$\endgroup\$
    – JRE
    Commented Aug 10, 2020 at 19:34

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