I have an old PS-303D from Conrad in use at home. Recently it showed a problem.
If I measure with my multi from V- to V+, the voltage reading is correct, current and voltage regulation seems to work fine. But when I connect V- with GND the supply turns off. Connecting V+ with GND is no problem. So I opened the case and did a little check ups. Soldering looks so far ok, and no visible damage has occurred. The GND is only connected to the case and via 2 ceramic capacitors to V+ and V- which seem ok. I looked at the schematic and I understand what each section is doing, but after a day of measuring I can't seem to find the error.
Can anyone point me to the right direction on how to approach the problem? Help would be greatly appreciated.