MB6HC 3v3 IO pins only have 1.06 volts

TechButterfly

I've been working to get my rebuilt D-bot running on Duet, and the endstops have not been working. So I got out my multimeter and apparently my 3v3 pins on the IO plugs only have 1.06 volts. I don't see anyway to adjust that. What can I do about that?

fcwilt

@techbutterfly

What are the labels on the pin(s) you are checking?

Thanks.

Frederick

TechButterfly

@fcwilt I don't see any labels on the board - beyond IO_0, IO_1, IO_2, etc. According to the diagram I'm looking at in the docs, they are labeled 3.3v. [url=https://imgbb.com/][img]https://i.ibb.co/zS4wbMW/IO-Pins.png[/img][/url]

fcwilt

@techbutterfly said in MB6HC 3v3 IO pins only have 1.06 volts:

@fcwilt I don't see any labels on the board - beyond IO_0, IO_1, IO_2, etc. According to the diagram I'm looking at in the docs, they are labeled 3.3v. [url=https://imgbb.com/][img]https://i.ibb.co/zS4wbMW/IO-Pins.png[/img][/url]

Great.

And you are saying measuring from a pin labeled 3.3 and a pin label GND you are not see 3.3 volts or thereabouts?

Frederick

TechButterfly

@fcwilt Correct. I've measured from both the GND pin on connector, and from the ground on the main DC input as well. From those points to the 3.3v pin is only 1.06 volts. I've also checked at the pin marked io3.in - that one actually had 3.3 volts on it, but I'm not sure what that means. In any case, the endstops aren't working - no LED when they are triggered, and no change in status when I run M119.

infiniteloop

@techbutterfly

I've also checked at the pin marked io3.in - that one actually had 3.3 volts on it, but I'm not sure what that means.

Measuring the 3.3V pins of IO_0 to IO_8 should always give you approx. 3.3V - at least if you remove all connectors (and I really mean: all) except of POWER IN. Did you try and measure that?

If you don’t read 3.3V under this condition, the board may be defective. Else, try to add one connector at a time and check the voltage of the IO_x pins: if it goes well below its nominal reading, you’ve found a potential culprit.

TechButterfly

@infiniteloop Thanks - the culprit is the connection to my CR Touch. I'll need to take another look at how I have it hooked up. With it disconnected, the voltage is correct, and my endstops are working. Thanks for the guidance!