Power supply problem for TPA3255 amp

[kapes]

Question for @ICIETDIYEUR or anyone that might have encountered this issue. I built a 42V, 350W supply with a component that was used by @ICIETDIYEUR on his onoorus D1 custom amp to power one of the TPA3255 amplifier. I'm using a switch on the AC supply side to turn it ON/OFF when I turn ON/OFF my TV. If the TPA3255 amplifier is turned ON while I switch the AC supply (load is ON while I turn on the AC of the supply), the power supply output toggles between 28V and 17V every second. If I had my amplifier OFF while I turn ON the AC side, output is stable at 42.4V and stays that way if I now turn the amplifier ON. Any idea what could be going on? The power supply vendor (although responsive) doesn't seem to be helpful. They want me to take it to a local electronic store to get this fixed. I'm sure that would cost almost 5 times what I paid for the supply. Any help is appreciated

 

[Wolf11Man]

The supply is not able to deliver enough current at start up to charge its own and the amps capacitors. It sees a short and the protection kicks in. If you have the amp off, it can reach full voltage and the protection is not triggered. Now you can start the amp, the supply capacitors have enough stored energy to charge the amps caps over the critical protection voltage and everything is fine.
Try another supply that may be more tollerant with capacitive loads.

PS there may be some kind of influence of the other stuff (TV?) switched on at the same time on the same mains outlet. Making things worse while starting up.

 

[kapes]

I tried another 48V 240W supply that was supplied with another amplifier and that works fine. I'll try testing it without TV or anything else on the socket tomorrow and report back

 

[wwenze]

Switched-mode power supplies hate capacitive loads

 

[ICIETDIYEUR]

Hello Kapes.

I don't understand why you're experiencing this type of problem, and I think your power supply must be faulty...

Indeed, I have NEVER encountered a problem of this type with my power supply, despite having tried various possible 'situations', such as a power outage followed by a quick recovery during a listening session, which in your case could be compared to flipping your ON/OFF switch.

Without being present in front of your equipment to test it, you'll understand that I unfortunately cannot be of any effective assistance, and I apologize for that.

(Just for your information, on my power strip with ON/OFF button, I have my power supply and D1 amplifier connected as well as a DAC, a PC and its monitor.)