This power supply gives me a 2Vpp ripple regardless of the output settings:



Here with output set at 2V DC.
This is the unit (is this repairable or should I junk it?):

 

The output set at 2Vdc with 2Vpp ripple?
Is it only at the positive side or it also at the negative side?
If you have Oscilloscope then choose a DC range which could handle over 40Vdc to measure the output of the rectifier diodes (it might be used Bridge rectifier diodes) that it from the transformer, or the input of the voltage control board, if you get the big ripple voltage then it could be the problem is at the filter capacitors.

 

Hi ScottWang, thanks for your reply! Where can I find a schematic for this supply?
My scope can handle 40Vdc, and I can see where the (rather small??) bridge rectifier sits, but I prefer to work from a schematic if possible?
Where would the voltage control part sit, which are the filter capacitors?

Thanks!

 

The board is all in one, what I called that the voltage control part is around the two 14 Pins and 16 pins ICs.
1. Using Oscope to measure the negative power (Gnd, -V) to make sure is it ok or not?
2. What's the rated voltage and ? uf of two big capacitors?
3. Using Oscope to choose a DC range which could handle the rated voltage of two big capacitors to measure two big capacitors of the left side in the second picture.
4. What are the ic numbers of 8, 14, 16 Pins?

 

That looks like a mains switch mod supply to me. DO NOT go measuring around in it unless you know what you are doing. There will be directly rectified mains power there. Very dangerous!
Here is a link to an old thread talking a bit about them...
https://forum.allaboutcircuits.com/threads/review-qw-ms3010d-30vdc-10a-power-supply.141258/

 

Hi dendad, indeed, that is why I need a schematic. The thread you show I had seen, thank you.
Connecting a scope to mains is the last thing I would do if ever.
So unless I find very specific information on this power supply I will not touch it any further.

The large ripple on the output worries me because of the fact that this is a switched power supply.

 

From what I have experienced, that power supply might be useful for powering motors, solenoids, lamps, battery chargers, and other projects where power supply noise would not matter.

It would not be recommended for applications where low noise power is essential such as logic and amplifier circuits.

 

This power supply has been sitting unused for the past 6 years because of this enormous ripple.

Today I needed it for some DC motor powering and took it from under the dust.

Dead as a duck.

Junk.

 

Hah, interesting. Check @MrChips review of the same model. Actually, barely a technical review but instead a QA review. Utter disaster.

https://forum.allaboutcircuits.com/threads/review-qw-ms3010d-30vdc-10a-power-supply.141258/