Connecting the ISORegen

[ogs]

I use a RPI4 with Ropieee in front of a ISORegen connected with USPCB. The IR connects to (and powers) a Sound Devices USBPre 2, also using a USPCB. This combination works.

However, the PS for the RPI4 is too small so (while waiting for a bigger/better supply) I need to power the input of the IR with a separate PS. I use the Aqvox USB PS for this (see pic). Now the RPI4 can not see the USBPre 2.

The Aqvox is simply inserted in the IR and the USPCB into this. Why is the USBPre 2 invisible in this configuration? I guess the Aqvox breaks + and - for power. It does work when the IR dip switch is togeled 'ON'. Does IR depend on a connected power shield to work? How 'bad' is it to use the IR in 'non-isolation' mode?

 

[ogs]

Just a ping to have either @Superdad or @JohnSwenson look at the above post

[Superdad]

6 minutes ago, ogs said:

Just a ping to have either @Superdad or @JohnSwenson look at the above post

Hi Ogs:

I am confused as to why you even need to inject 5VBUS to the input side of the ISO REGEN.  While it does required 5VBUS—to power the upstream side of its Silanna galvanic isolator chip—it draws only a very tiny 20mA from the VBUS.  So regardless of how small your RPI4 power supply is, it should be able to handle an extra 20mA.

[ogs]

Thanks. 20mA is very little. I'll connect it back as soon as I get a better supply. The Aqvox is a better supply than the average phone switcher. but is only 1000mA.

What puzzles me is why USPCB+Aqvox doesn't work while USPCB alone works.