Strange Resistor Color Code Identification Help YL,VL,GLD,GLD,BLU - Page 1
Forum section: electronics / beginners

author: Mikek400
author_rank: Regular Contributor
timestamp: April 08, 2020, 02:47:16 am
content: I have a dark brown 2W(I think) carbon composite resistor that hasthe color code Yellow Violet Gold Gold BlueI have no idea how to read this resistor with gold being the third digit. It measures open circuit on the ohm meter so I can't find its value that way.It is at the input of a SMPS on a refrigerator control board before the full wave bridge diode array.I have seen pics where the resistor appears to be a different code than mine. The other code I have seen is Yellow Violet Gold Silver Blue.The TNY267G before the transformer is shorted out and that seems to have killed the resistor.It is R65 on the right hand side of this picture at the bottom above the blue MOV. This isn't my board but one of the many pictures I have seen of it online with the silver stripe instead of gold.Any help would be greatly appreciated! I've got a new TNY267GN and some opto isolators that seemed to be burnt out along with new caps on the way from digikey. Hopefully can get this thing fixed.

author: Mikek400
author_rank: Regular Contributor
timestamp: April 08, 2020, 02:54:49 am
content: Here is the actual resistor.

author: golden_labels
author_rank: Super Contributor
timestamp: April 08, 2020, 03:10:37 am
content: Possibly:digit1 | digit2 | multiplier | toleance | temperature coefficientThat would be: 47·10-1Ω, 5% tolerance, 10ppm/K.

author: admiralk
author_rank: Regular Contributor
timestamp: April 08, 2020, 03:25:01 am
content: Quote from: Mikek400 on April 08, 2020, 02:47:16 amAre you sure you are reading that the right way around?

author: Mikek400
author_rank: Regular Contributor
timestamp: April 08, 2020, 03:27:50 am
content: No, Im not sure which way is correct. It could start from blue but then it would be blue gold gold violet yellow, which doesn't make any sense at all either.I think the reply from golden_labels makes the most sense. I thought it might be a 4 band resistor code with some extra band at the end. The only other conclusion I can come to is that they ran out of paint and substituted gold for some other color, but seems unlikely.

author: SilverSolder
author_rank: Super Contributor
timestamp: April 08, 2020, 04:14:47 pm
content: What an odd resistor...I found this ancient color coding scheme, which supports @golden_labels' suggestion (but does not cover the temperature coefficient).

author: drussell
author_rank: Super Contributor
timestamp: April 08, 2020, 04:35:09 pm
content: I agree withgolden_labelsabove, probably 4.7Ω 5% tolerance, 10% temperature coefficient.That sounds about right if it is intended to provide a little bit of "cushioning" on a power input.How exactly is it being used in the circuit? When you say it is being used before the bridge rectifier, you mean it is right on the mains coming into the primary side of SMPS, right? It is difficult to know for sure just looking at the top of the board how it is connected.The difference between the gold/silver band that you have seen elsewhere would be 5% vs 10% tolerance, which wouldn't be critical in this application. Interesting that it does look like carbon instead of the typical flameproof fusibile-style resistor that would often be used in such a position if that's really what it is.

author: David Hess
author_rank: Super Contributor
timestamp: April 08, 2020, 05:03:39 pm
content: 4.7 ohms 5%

author: madires
author_rank: Super Contributor
timestamp: April 08, 2020, 05:13:26 pm
content: It's a fusible resistor 4.7Ω 5%. The blue color band is the manufacturer's way to indicate the resistor type. Other manufacturers may use a different color.

author: Mikek400
author_rank: Regular Contributor
timestamp: April 08, 2020, 09:22:07 pm
content: drussell,It is directly connected to mains coming in and then connected to the bridge rectifier. That being the case, what madires says about it being a fusible resistor makes a lot of sense, because it would be working as a fuse as well.Thank you everyone for your help and input. I don't have any fusible resistors so I might just add a small fuse to the input for safety after replacing this and getting it working.