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Voltage question


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Got the ac wired up to the power supplies. When I checked the dc voltages I can’t get them adjusted to below 26 and 6.5 volts respectively. I bottom out the potentiometer. Is this acceptable or is it simply because I have no loads on either unit?  Reluctant to hook up the octopus or pi until I know for sure. Anybody else run in to this?

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sounds like something else is wrong. I would not connect anything until you figure out why the voltage is off.

Silly question and no offense meant, but have you verified the line voltage input setting on the side of the power supply?

A few thoughts - use a LED lamp with a current limiting resistor as a small load just to check attached to the power supply directly.

Have you checked your voltmeter... according to the RS-50-5 specs, the voltage should not even go up to 6.5 vdc. The LRS-200-24 has an adjustment range from 21 to 28 vdc.

Are you checking the power supply by itself or is wiring involved? Maybe there is a weird ground loop going on.

That is all I can think about at this moment...

Let us know...

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40 minutes ago, VPP_Team said:

Put a non critical static load on them and check the voltage. Also, the 24v input is considered a nominal voltage, contact BTT and see what the input voltage range is, I’m betting it can handle it.

BTT allows up to 28 vdc, so it can handle it if it is really 26 volts. The Mean Well supplies are switching regulators with excellent regulation. To have two separate supplies be out of tolerance and not be able to adjust them to what they support, still points to a different issue.  Of note, the RaspberryPi 4 does not accept a voltage past 6 vdc according to its specs.

If I had Mean Well supplies that actually could not be adjusted to the correct voltage, they would be going back to where I bought them.

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1 minute ago, VPP_Team said:

Are they Meanwells? My assumption was they are cheap PSUs from the details given, which are usually slightly over volted to aid in sustaining the nominal 24v under a load.

Being an electronics engineer, I try to never assume anything.  Personally, I would not use anything but Mean Well with the money invested in the rest of the Voron.  The power supply make wasn't stated, but even the cheap switching regulators I have used for replacement in my Anycubic i3 Mega-S printers have good regulation up to their rating.  Over voltage is something that any regulated supply should not have unless it was failing. The old power supply bricks from twenty years ago did have a higher voltage and would drop to something close to the stated voltage on it, but only with a load. The equipment they powered tolerated the differences.

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They have an mw on them so I just assumed that they are meanwells. I take a better look tomorrow.  My meter is a cheap one.  And setting the kings voltage was the first thing I did. I did measure the ac input and it was higher than expected. It read 145.  I had electrical issues in this room which was an addition but that was with the lighting wiring. However the electrician who fixed it put the ground and neutral together instead of figuring out where I was losing the neutral at.  I wonder if this could be causing a new issue with the rest of the addition. Waiting for another electrician to come fix it. I’ll have to check the outlet voltage cause it shouldn’t be that high and compare it to a different room and go from there. Thanks for the input and suggestions. I greatly appreciate it. 

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39 minutes ago, SteveThatcher said:

Being an electronics engineer, I try to never assume anything.  Personally, I would not use anything but Mean Well with the money invested in the rest of the Voron.  The power supply make wasn't stated, but even the cheap switching regulators I have used for replacement in my Anycubic i3 Mega-S printers have good regulation up to their rating.  Over voltage is something that any regulated supply should not have unless it was failing. The old power supply bricks from twenty years ago did have a higher voltage and would drop to something close to the stated voltage on it, but only with a load. The equipment they powered tolerated the differences.

Lmao, you assumed they were meanwells, lol. I’m an engineer as well.

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17 minutes ago, Pappy3831 said:

They have an mw on them so I just assumed that they are meanwells. I take a better look tomorrow.  My meter is a cheap one.  And setting the kings voltage was the first thing I did. I did measure the ac input and it was higher than expected. It read 145.  I had electrical issues in this room which was an addition but that was with the lighting wiring. However the electrician who fixed it put the ground and neutral together instead of figuring out where I was losing the neutral at.  I wonder if this could be causing a new issue with the rest of the addition. Waiting for another electrician to come fix it. I’ll have to check the outlet voltage cause it shouldn’t be that high and compare it to a different room and go from there. Thanks for the input and suggestions. I greatly appreciate it. 

What’s the model number? Also, if it’s hard to determine, post a few pics of them.

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As the reading on both power supply is high, did you check your voltmeter (multimeter). There is a remote possibility that it is giving an incorrect reading.  As for the input voltage, this is unlikely to be the cause, if you set it incorrectly you would simply blow the input stage of the power supply. I agree that even a cheap PS nowadays can produce the correct voltage at no load. 26V if stable should be fine but 6.5V is way too high for safe operation. 

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Thanks Stephen. I thought about that last night while I was getting ready to call it a night. I’m going to borrow a meter from work and recheck. This morning I went straight to the source in various outlets and the meter read 150 volts. I’ve never seen readings like this before when I’ve done work with electrical but that was with a different meter. Which I have misplaced. Even my high dollar monster power unit on my home entertainment systems shows an input display of 124 volts. I’m really beginning to think my cheap 7 dollar meter is giving me false readings. So I’ll borrow or buy a better unit and see if I get different readings. 

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Update. Brought a good meter home and lo and behold my outlet voltage was 124. After making sure the ground on the plug and the frame had zero resistance I plugged it in and turned it on. The dc voltages we’re just under 21 volts and 4 volts. So I had to turn them back up.  Now sitting at 24.1 and 5.04 volts respectively. Thanks for all the input. Just glad it was a cheap meter that caused the problem and not the psus or something I did in the build. 

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