Newbie - Help me identify this power supply component?

Hi,

I'm new to electronics, and am trying to learn how switched mode power supplies work.

I'm reading as much as I can, and I find it helpful to learn by taking apart old power supplies to try and understand their operation.

I have come across this component today which I have not seen before.



It has 6 pins (although the bottom pairs are joined), and is circular in appearance. I normally search the part number to obtain a description of the part, but I cannot find any datasheet or mention of the part on Google. I thought it was some form of transformer, but the PCB abbreviation is L004, which suggests an inductor?

I am guessing that the text "Hi-POT" on the part means "High Potential", but does the other text, like 21k78 mean anything, or is it just the part number?

A second query I have refers to a pair of resistors that is also on the same board. I am used to decoding 4 band resistors, but not 5 band resistors.





I read the resistor as:

1st Band: Brown
2nd Band: Black
3rd Band: Gray
Multiplier: Brown (x10)
Tolerance: Green +/- 0.5%

Value: 1.08k Ohms (.5% tolerance).

Is this correct?

Many thanks for reading my questions, and any help is appreciated!

Transformer.

quantum5 said:

"Hi-POT

Click to expand...

Hi Pot. A transformer most have a seperation between Primary and Secondary. This is what keeps you safe from the power line. Hi Pot is a test where they test with 2000 volts.

quantum5 said:

It has 6 pins (although the bottom pairs are joined), and is circular in appearance. I normally search the part number to obtain a description of the part, but I cannot find any datasheet or mention of the part on Google. I thought it was some form of transformer, but the PCB abbreviation is L004, which suggests an inductor?

I am guessing that the text "Hi-POT" on the part means "High Potential", but does the other text, like 21k78 mean anything, or is it just the part number?

Click to expand...

I would suggest it's most likely an inductor, used as part of a switchmode PSU - simply because the top two pins look to be physical mounting points, and not connections, so it's only a single winding. If the top two are a winding, then it's a transformer.

You're not going to find anything on google, as all such items (both inductors and transformers) in switch-mode are almost always custom made.

actually that resistor is 1.09k which means that band is white. 109 appears on the [E196 chart] but 108 doesn't. i like it better when precision rexixtors have digits on them instead of color coding. 5-band resistors are too easily read backwards, and certain lighting conditions can lead to misinterpreting the colors of the bands. i once built a prototype board, and the engineer had specified 1% tolerance resistors in locations where precision wasn't an issue (pullup and pulldown resistors on logic gates). to save his company money shelling out for high priced 1% parts, we ordered 5% parts. the engineer said that was ok for the production boards, but he really needed the 1% parts on the prototype.... because he was color blind... i'm not color blind, but the resistors with text are unambiguous, and certain types of fluorescent lighting suppresses certain colors, like red, which makes telling brown, red, orange, and yellow apart difficult (under certain lights, brown and violet are hard to tell apart). one of the customers we had at that prototyping company had sodium vapor lamps on their production floor, which is THE WORST lighting for reading resistor color codes.

Transformer in some peoples opinion is correct, however you might say its a coupled inductor, as its the inductance of the windings thats important during the design stage.
The core looks like what in the Eu would be called a 'pot core'.

quantum5 said:

1st Band: Brown
2nd Band: Black
3rd Band: Gray
Multiplier: Brown (x10)
Tolerance: Green +/- 0.5%

Value: 1.08k Ohms (.5% tolerance).

Is this correct?

Many thanks for reading my questions, and any help is appreciated!

Click to expand...

Take a look here for a nice resource for getting the value of the resistors.