Better not: ATTEN APS15-3A

[Phil1977]

I thought I could use a small linear power supply for the bench and got a good offer from a quite reputable German supplier: The ATTEN APS15-3A.

From the first glance it looked like a no-brainer: 15V, 3A, analogue current meter, digital voltage meter.

But looking inside changed the mood:
- A really chaotic design. The device uses 5 (five!) PCBs, partially connected with flexPCBs.
- Mains lines directly touch PCBs on the secondary side so that soldered pins scratch on the insulation - and that´s no double or reinforced insulation (see second pic)
- The 5V for the USB-port are generated with a switching mode buck converter (XL4015E). Usually I'm not afraid of switching mode DC DC's, but if I explicitly buy a linear power supply then it should be completely linear.
- The 5V of the USB-port are not galvanically isolated
- No constant current mode, only overcurrent protection
- The transformer has a quite loud hum

There are also a few positive points:
- The control of the output voltage is set by a digital encoder. In it´s fine-setting (by pressing the button) the voltage can be controlled in 2.5mV-steps.
- No ripple of the XL4015 is visible on the main output with a standard scope in AC-coupled 10mV/div settings.
- The fan is temperature controlled
- Nice compact form factor
- A beeper warns you when the OCP is triggered