Can anyone help me ID the corroded? resistor R32 in this image? It is about 11mm long and 5mm wide. I think it's a 300k 1w resistor, but the packaging is throwing me. The board is from a UPS which is working fine but I was going over it while replacing the batteries and saw this. I know "toss it" but I am curious what it is. R49 in the background is similar but more of the typical shape.

 

The resistor is 15Kohms, 1%, I would guess from it's size that it is a one watt resistor. I think the black stuff on the lead is the remains of some insulation.
Regards,
Keith

 

I was reading the color code bottom up for R32, since most charts don't have a tolerance code for black. How does one know which way to read it?

The black tube is insulation. It's the green fuzzy stuff on the leads and at the board that concerns me.

 

I was reading the color code bottom up for R32, since most charts don't have a tolerance code for black. How does one know which way to read it?

The black tube is insulation. It's the green fuzzy stuff on the leads and at the board that concerns me.

There's usually a gap between the bands for the tolerance. Heat could have changed the color.

There are other rules that you can use to decide which end to start from. Black and gold aren't valid for the first band; unless the resistor is zero ohms (a single black band). There are always exceptions to rules.

I wouldn't worry too much about the corrosion. Just clean off what you can so it doesn't get worse.

 

I was reading the color code bottom up for R32, since most charts don't have a tolerance code for black. How does one know which way to read it?

The black tube is insulation. It's the green fuzzy stuff on the leads and at the board that concerns me.

The bottom band looks like black in the picture, that indicates 1% tolerance. See attached chart: It is confusing because there are so many different ways the value and tolerance are indicated.
Use a bit of baking soda in water and an old toothbrush to gently clean the corrosion away. It looks as though battery acid got on the lead.
Keith

 

I'd prob replace it myself but definitely clean it and reflow it at least. Maybe the corrosion has done a little more damage to it then we can see. Its been heating up pretty bad it looks like.

 

I was reading the color code bottom up for R32, since most charts don't have a tolerance code for black. How does one know which way to read it?

The black tube is insulation. It's the green fuzzy stuff on the leads and at the board that concerns me.

There is a simple way to know the correct sequence for reading the stripes, but it does require a bit of study. That is to apply the MAZALOWSKI PRINCIPLE, which is to consider, "Is this answer reasonable?" Reading from the bottom up would give 0351ohms, which is not reasonable for two reasons, first, because leading zeros are never used for resistors, and second, because 351 ohms is not a standard value for 5%, 10%, or 20% tolerance resistors. But you do need to be familiar with the table of standard resistance values as well.

 

I would go with the 15k 1% also, but measuring would confirm, it is still intact!.
Max.