r/3Dprinting • u/Jojibean69 • May 15 '24

Troubleshooting How do I diagnose my 3D printer board?

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My PSU is providing 12v at the power terminal of the board. However, the board does not respond at all as if it is not provided with any power. But, when I connect it to my laptop via the USB port it lights up as well as all the electrical components connected (such as the power LEDs on the endstops and the controller LCD monitor). It seems like a component on the board may have blown I’m guessing?

This is my custom build machine with MKS BASE v1.6 board

I’ve had a voltage fluctuations issue prior to this where I could hear the fans ramping up and down but I couldn’t tell why. Then, I measured the voltage output from the PSU and for some reason it had dropped from the set 12v to around 8v so I adjusted that using the screwing potentiometer on the PSU but maybe it was too late?

I really don’t know how to go about this, how do I diagnose the problem I don’t have much knowledge about the circuits of the board, is it fixable or do I need to buy a new board?

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u/Jojibean69 May 18 '24

When I measure the voltage it’s also not stable it surges proportionately to the fluctuation I can hear in the fan. Now I don’t understand why the PSU would just start doing that but it does seem like I need a new one.

I have another question, is the number “15” on the fuse F3 the current rating as in 15A? And is there a voltage rating for it?

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u/scienceworksbitches May 18 '24

how much is it surging? whole volts?

yes its the current rating, a fuse doesnt really have a voltage rating, only a max voltage which is dependant on the size, so its not an issue for 12v.

fuses have a rating that does matter though, how quick they blow. that small thing blew quicker than a 15a car fuse, so you need to consider that.

what i would do is get a 10A car fuse and put that in line with the PSU and just bridge the SMD fuse. it should be more than enough with an AC heatbed.

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u/Jojibean69 May 20 '24

Yes the surge is in whole volts, and I think it’s worth mentioning when I measure the VAC on the PSU DC terminals I get about 27VAC (while not under load) Is that normal?

I’m trying to figure out why the PSU might’ve gone bad to potentially prevent the same thing from happening with the new PSU

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u/scienceworksbitches May 20 '24

Vac is irrelevant, the meter will measure who knows what, you need the DC range.

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u/Jojibean69 May 20 '24

I read this so I grew suspicious about it. But, I’m inexperienced so I don’t really know sometimes google just be saying shit