Help with Resistor Identification

Chad de Aguiar · Sep 12, 2019

Hi there

First time posting on forums for help because I frankly can't get this right haha.

I've got a power supply unit for a Tube Condenser Microphone that's blown a couple of components. A capacitor burnt out which I've already identified and I have a replacement on the way but for the life of me, I can't figure out this resistor. I've tried the colour code calculators and they seem to just not work. Any help identifying the unit would be greatly appreciated!

It is a metal film resistor for sure but the colour code doesn't seem to work.. From the left, the colour strips seem to be white, brown, silver, black, black and red. Please help if possible. Thanks guys

rjenkinsgb · Sep 12, 2019

I'd read it from the opposite end and say it's 20 Ohms, most likely

Where is it in the circuit?

Chad de Aguiar · Sep 12, 2019

I tried that but it doesn't seem to work with the colour code identifier ending on a white strip.

It's sitting between one leg of a transistor (at least I think it is) and a capacitor and diode. The negative pole of the capacitor that swelled was on another leg of the transistor (and it's positive pole was connected to what I assume is power out the tube in the microphone). Sorry I wish I could tell you more but I'll send a couple of photos and try annotate them as beat I can.

rjenkinsgb · Sep 12, 2019

Looking at the other photos, they appear to be four-band (for resistance value) type, with the two close together being tolerance and temperature coefficient,

Red-black-black-silver is then two ohms, brown is 1% tolerance and white should be TC, but white is not a standard code. It may be manufacturer specific.

Measure the value of one of the good ones to verify that is the correct reading direction; blue grey black brown should be 6800 Ohms.

tvtech · Sep 12, 2019

I always battle with any resistors other than standard marking ones. Imma 5 to 10 percent tolerance guy. My codes are OK... but often I battle with stuff that has discoloured.

Kieran123 · Oct 1, 2019

Hi
Can someone help me with this please?
I'm confused with the colours.

Pommie · Oct 1, 2019

Looks like orange, black, brown which would be 300Ω. Is there another that you can measure?

Mike.

KeepItSimpleStupid · Oct 1, 2019

red-blk-brn-gold = 20.1

tvtech · Oct 1, 2019

Brown Black Red Gold
Standard 1K resistor 5% tolerance

Nigel Goodwin · Oct 2, 2019

Kieran123 said:
Hi
Can someone help me with this please?
I'm confused with the colours.

As is obvious from the previous replies, the resistor has seriously over heated, and the colours have changed so it's pretty well guess work what the colours are supposed to be.

The only obvious one is the gold (5%) tolerance band.

So could be 300 ohm, could be 1K (I'd edge towards 300 ohm, although it isn't an E12 value it is an E24 one) - what it can't be is 20.1 ohm, silly suggestion by KISS

What exactly does the resistor do?.

Kieran123 · Oct 2, 2019

Thank you for answers. No Pommie this is the only one on a board. Just bought a 300 ohm resistor and will give it a go. Yes Nigel the tolerance is definitely a gold one and the second band black.

JimB · Oct 2, 2019

My best guess is Brown Black Brown Gold, which would make it 100 Ohm 5%.

I understand that others think that the multiplier band is Red, rather than Brown.
I have considered that possibility, although the multiplier Brown is darker than the first number Brown it has also been subjected to much higher temperature, hence the darker colour.

JimB

tvtech · Oct 2, 2019

JimB said:
My best guess is Brown Black Brown Gold, which would make it 100 Ohm 5%.

I understand that others think that the multiplier band is Red, rather than Brown.
I have considered that possibility, although the multiplier Brown is darker than the first number Brown it has also been subjected to much higher temperature, hence the darker colour.

JimB

Brown Black Brown. Yes Jim. That makes a lot of sense mate

One hundred ohms with 5% tolerance.

Pommie · Oct 2, 2019

As you have the original and can look at it under sun light, what colours do you see?

Mike.

Kieran123 · Oct 3, 2019

Just put another one in and it has started to shine, great. I hoped it will be an easy fix. Any ideas where else the problem might be?

tvtech · Oct 3, 2019

Shine as in glow or get hot?

Pommie · Oct 3, 2019

Wow, big circuit board with thousands of components and one big resistor. Must be important. Which bit started shining?

Mike.

tvtech · Oct 3, 2019

That big black cap looks like a missile armed and ready to launch

Kieran123 · Oct 3, 2019

This is a bosch dishwasher pcb. It took a couple seconds for the new resistor to get extremely glowing hot and obviously it has blown again. No other dischwasher parts were conected so basically there was no load on pcb.

ChrisP58 · Oct 3, 2019

Kieran123 said:
This is a bosch dishwasher pcb. It took a couple seconds for the new resistor to get extremely glowing hot and obviously it has blown again. No other dischwasher parts were conected so basically there was no load on pcb.

Sounds like there is something else on the board that has failed short, and the resistor is secondary damage.

You'll need to find the primary fault before replacing the resistor again, or it will keep on blowing.

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