Superberg

I had a similar problem with my boards some time ago. The problem in the end end was a layout issue on the board with the optocoupler based psu delay circuit. In my case the -400V worked fine and +400V was not rising. Check what board you have and maybe remove the optocoupler. Sent from my LG-H930 using Tapatalk

Thanks Soren, It looks like I am lucky enough and have the version 1.8 that is messed up! I had a hard time finding the "correct" cicruit diagram and gerber files for my boards. In additiona to that, I didn't check the layout properly and I was getting confused because of the resistor values since the output current source in my case also uses 600R insted of 1k. I thought that 600R was for the CPC! Only once you told me to look at the CPC I noticed the layout issue! I removed the CPC and now it works. I am getting 409 V at the output now. I have to tidy up the board a bit cause I burned the 3k resistor in the process and don't have a replacement. Thanks a lot again, I should have posted earlier! At least now I understand how the whole PSU works ? Martin

Hi, Yes, I did populate the CPC since at the beginning I didn't have have enough time to think what was what in the circuit. I am using 2k8 resistor since that was on the solder mask! I also tried with 4k7 at some point but it didn't seem to help. What would be your advice? Remove the CPC change the resistor? To what value? It is very strange though that the positive supply works and it is built in exactly the same way!

Hi, I am new to this forum and I would need help regarding the power supply for KGSSHV Carbon. I have built the positive and negative power supply on single boards version 1.8. The positive supply runs without any issue but the negative does not start. I spent a few days on this already and I am not sure what to try anymore. The problem is that the output voltage sits at 18.56 V and remains there with only 0.46 V across the 20k sensing resitor. Both current sources are running since I am measuring 10 V on LT1021-10 and 12 V across the zener diode. The problem seems to be related to STN9360 and the circuit around it. The emiter to base voltage is approx. 8.56 V with base being positive. The input current source provides approx. 0.76 mA (checked with 20 V DC source, R1=2.8k as on the silk screen). Drain of the SiC MOSFET sees full 460 V as it should but the Gate Source voltage is only 2.58 V. I am not sure what to check anymore. Maybe someone has an idea where the problem could be? I replaced almost all the semiconductors in the meantime but nothing helped. The strange thing is that the positive supply is populated in exactly the same way (same component values) and it runs without any issue from the beginning. Regards, Martin