Gophert CPS-3220 oscillation

[radud5]

Hi all,

I have Gophert CPS-3220 without any schematic.
I find inside TNY274 for permanent 12V and TL494G
I have oscillation for low load:
   12V 0,08A ... 0,15A  0,27A ... 0,33A
   5V  0,04A ... 0,55A  0,73A ... 0,87A
   4V 0,04A ... 0,8A 1A ... 1,12A
   2V  0,03A ... 0,95A  1,2A  ... 1,55A
   0,1A 2V ... 15V
Oscillation is stronger on low voltage.

Please help me with solution to reduce oscillation on low load.
Thanks,

[HB9EVI]

too little info here; how do you know there are oscillation? did you scope it? can you show us?

[radud5]

Video

I couldn't record the oscillation sound. It has a high frequency.

[electr_peter]

I know this is an old topic, just wanter to clarify few points.

Video above seems to show setup of Gophert CPS-3220 set to 5V at some high current limit, DL24P set to 0.1A CC load and some oscilloscope presumably connected to current shunt.
After turning 0.1A CC mode on, load current oscillation is visible on both scope screen and current meter while voltage is rock solid at 5V.
This indicates that DC load is oscillating, not Gophert PSU.

DL24P electronic load is far from perfect, OP tried to improve it cheezeball-dc-load-dl24p-pump-or-dump

[HB9EVI]

can be, cannot be. the video shows pretty much nothing, that's likely why there were no further replies.
both devices, the scope and the load are just toys; you can hardly call that measuring, and TO didn't come back to thread, so it's nothing but speculation

at least my Gophert 6017 works without any oscillation at any random current and voltage

[electr_peter]

Well, provided data is sparse, this is my interpretation what's available.
It is known problem (in general) for DC load to sometimes be unstable (especially at low 0.1A current for specific DL24P, see other threads). On the other hand, Gophert 3220 (capable of 32V/20A) probably didn't notice 0.1A load at 5V, PSU was in CV mode (current setting was higher). And there was 5V reading with or without load.
Oscillation could occur if PSU is set up for CC mode or on CV/CC edge and loaded with active load, this was not the case.