On Fri, 01 Jan 2021 23:32:43 +0000, Nikolaj Lazic wrote:

> Dana Fri, 1 Jan 2021 20:53:25 -0000 (UTC), bob prohaska
>  napis'o:
>> Just tried using a couple of USB card adapters with my 8GB Pi4.
>> Both cause immediate loss of USB hard disk access. Unplugging the
>> offending adapter does not restore normal operation. Power cycling puts
>> matters right without apparent ill effect.
>
> Not enough power?

From your description it sounds as if you're booting with the adapters
disconnected and the hangup occurs when one or both are connected to the
Pi. Is that what happened?

Do they work correctly when used together on another computer?

Have you got a multimeter, osscilloscope or any other way to check the
Pi's supply voltage?

-------
I tend to keep a Pi power cable modified so I can measure the voltage
across it. I run the cable through a small plastic box with terminals on
the lid, the terminals are type used on oscilloscopes or multimeters for
connecting test probes. These are worth using because they're difficult
to short accidentally. The terminals on the box are connected to the red
and black wires in the power cable. So that putting a multimeter or
'scope across them lets you monitor the supply voltage going into the Pi.
I sometimes put two terminals in series on the red cable with an on/off
switch on the bit of wire between the 'red' terminals: this makes current
measurement easy: turn the switch off and connect a meter on the two 'red
terminals to measure current. Don't wanna measure current? disconnect
meter from red terminals and turn the switch on. You mightn't use this
gadget very often, but boy is it useful to have one when you suddenly
need to check voltage or current in a USB terminated cable.

Farnell, Conrad and similar outfits sell suitable boxes and terminals as
well as soldering irons and multimeters


--
--
Martin    | martin at
Gregorie  | gregorie dot org

--- SoupGate-Win32 v1.05