New build HW5 version - error at first SD read tests when set to 5 V, but works fine with 3V

[feliszingiber]

Hello,
I am following the build guide and am at stage 6) "The first test". I am greeted by the menu when the switch is set to 3.3 V, but when I switch it to 5 V mode, I get the SD error - press button .... message.
Where could the error be?

[sanni]

Probably best to go over all the solder joints again making sure all connections are solid.
If you have a multi-meter you can measure the voltage in 5V mode, there could be a short circuit somewhere bringing the voltage down, e.g. one of the three middle pins of the switches bridging to the two outer pins.

[feliszingiber]

checked all my solder joints, redid those that looked funky and some more - no change. No short circuit at the switches.

I made some new observations:

• Turning on the power switch in 3.3 V mode --> Blue LED lights up and greeted by menu
• Turning on in 5 V mode --> Blue LED doesn't light up and greeted by SD error.
• Turning on in 3.3 V, then switch to 5V mode while on --> LED becomes brighter and the menu stays

I also measured some voltages around the pins connecting to the MKS Mini. in 3.3 V mode, some pins (D10, D12, D39, among others) read 3.8 V, in 5 V mode they read 4.7 V. Can that hint at the error?

[cmcm711]

Just a basic check, but if you haven't already, try using a different USB cable and AC adaptor, then check voltages again.

[feliszingiber]

Tried swapping things around. What finally fixed the problem at this stage: swapping the IDC female ribbon connectors that were included with the MKS Mini for older ones I had luckily lying around. No idea what exactly was wrong with those cables, I might check them at some point...

Now I can continue assembling :)