DC-DC AdjustableCE07271 Step Down Module not changing voltage

Hi there, Core Electronics

a few months ago I purchased two of these DC-DC Adjustable Step-down Module 5A 75W | Core Electronics Australia and only got around to unpacking and using them today to work on a project, now that I finally have a break :slight_smile:

For context, I was expecting to be able to apply 12-13V and set the output to 5V, as this is within the spec range, and then ideally, have it maintain 5V even if the input falls down to 11V.

According to the instructions, adjusting the screw of the potentiometer closest the input should alter the output voltage, however, it seems to have no effect. When I connect 12V to the input I measure the exact same 12V (12.32 in practice) on the output, regardless of how much I adjust the pot. Similarly, when I put 5V on the output I also got 5V on the output. The red light is not on. So it appears the module is just following the input…

The current mode appears to be working - I hooked a potentiometer on the output and when I moved it close to short briefly, the blue LED turns on. I did not have a high power resistor handy to test if it is really working.

To me this appears to be a fault, i.e. the voltage regulator is not working, unless I’m misunderstanding something completely obvious in the “instructions” shown on the page. This behaviour is the same on both my modules, so this is possibly still operator error - what further testing should I perform before I try and work out how to claim for a faulty product?


Hi Andrew.
Something similar has come up before and it turned out to be the pots not turned far enough.
You do realise these 2 pots are at least 10 or probably 20 turn pots. If they were turned up any way near maximum the device probably would just repeat the input voltage.

If they were turned up to anyway near max it would probably some 15 full turns or so to reduce below 12V, The max input is 38V, quite a long way when you are turning a small screwdriver.

Turn the current limit to Max while adjusting voltage to prevent any current limiting.

When these pots get to their extremities they produce a faint clicking sound as it ratchets over without breaking anything.

The set up procedure is.

  1. With current limit at max set required voltage. No load.
  2. If current limiting is required set current limiter pot to min (fully anticlockwise). short out the output with current meter. Increase pot until required current limit point is reached. The voltage will reduce while doing this but this is normal.
  3. Device should be ready to use.
    Cheers Bob
    PS. If this turns out to be the problem don’t be embarrassed, It has happened many times before you.

Hey, that worked - thank you!

I had to wind it out a very long way, to get to 3.3V in the end :slight_smile:


Hi Andrew
Yes I think those pots are 20 turns. Can seem like forever when the rotation using your fingers on a small screwdriver is probably about 1/3 turn and with 38V possible input you are only using the bottom 10% or so.

As this comes up every so often if Core are reading this (I imagine they are) I wonder if it would be a good idea to include some explanation of the setting up techniques and warnings about 20 turn pots. It may prevent some perfectly good units being returned as supposedly faulty. We only see the ones that make the Forum. There are probably a lot more that ere not generally known.
Cheers Bob
PS. Thanks for sharing the result.


Good idea Bob @Robert93820 ! I’ve added it to the to-do list for when we get a moment.
And glad to hear you got it working @Andrew123957 :slight_smile:

Hope you both had an enjoyable Christmas!