ALLO 5v power supply - 90 volts from dc terminal to earth

[Cprogrammer]

Does anyone have this power supply? Can anyone having a multimeter connect the power supply to the wall and measure the AC voltage between the negative terminal to earth. I am getting 90 volts between any of the terminal (positive or negative) to the ground. Also I have tried reversing the phase neutral polarity to the supply pins of the power supply. The voltage remains as 90 vots. I have measured the voltage for other similar power supplies I have and most of them have voltage below 20 volts. I am wondering if this power supply is a SMPS or a linear power supply (most likely it is a SMPS from the small size of the adaptor). Does anyone else here know what kind of power supply is this allo power supply - https://www.allo.com/sparky/5v-power-supply.html

 

The issue I have is almost all my equipment have floating ground (dac, amp). My plasma television was connected to the same power outlet and the day I got my sparky+kali+piano 2.1 connected to my rig and powered by the allo power supply, I started noticing a thin red line on the plasma television. Initially I did not draw any relation that this started happening from the day I connected the sparky+kali+piano2.1+allo power supply combo. While browsing some topic about someone else in this forum who has developed a technique to ground the negative of SMPS to earth, I decided to measure the leakage and found this 90 volts. The current must be very negligible because I don't get any shock. Also the DC output is exactly 5v. After disconnecting the allo power supply I find that the thin red line has disappeared. Luckily no damage has happened (probably because the leakage current could be negligible). But I am sure this will have some impact on the audio as the leakage will find some way to reach the ground. I am wondering If I an isolation transformer help in isolating my plasma tv from the rest of the equipment. Probably any equipment like a PC with a noisy SMPS also needs to be isolated.

 

Can anyone else here measure the voltage they get with their own power supplies. One just needs to connect the power supply to the wall, connect one terminal of the multimeter to the metal barrel of the DC jack and other terminal to a earth pin on the wall. It will be interesting to see what we get with other power supplies like the ifi power supply.

 

I have made linear power supplies using LM 317 regulator. Most probably I will do that and see if Allo can send me another power supply. I have temporarily disconnected the power to the allo board and in two or three minds but yet to figure out which will be the best option.

 

1. Buy another power supply

2. Make a traditional power supply with a trafo, lm317 regulators and large caps. This will be the cheapest but the ugliest for the lack of a proper unit for housing it.

3. Make a contraption to connect the DC negative of any such SMPS to earth.

 

Please refer to this document about SMPS grounding

 

[nbpf]

Here are my measurements:

 

Allo 5V/3A :                        84.5V  (negative and positive)

ifi 5V/2.5A:                         48.5V  (negative and positive)

UpTone Audio LPS-1.2:    0.0V  (negative and positive)

UpTone Audio JS-2:           0.0V  (negative and positive)

 

Best, nbpf

[Cprogrammer]

Thanks nbpf. Just for knowledge purpose, I measured with many power supplies. The apple power supply gave around 45.6 and my samsung phone charger gave around 25.1 and all my LPS gave 0.0v.

 

I am now convinced to use John Swenson's technique of grounding the negative terminal of these SMPS based power supplies.