Meanwell RT-125A

PCB problems and fixes
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Sunder
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Meanwell RT-125A

Post by Sunder »

So I bought a bunch of Meanwell PSUs because I was told that this was the best modern quality stuff to use with my arcade pcbs.

And it's not working. It barely outputs 5v out of the 5v line, even cranked all the way up for my MVS 4 Slot. What gives?
Heck even my crummy 12 dollar 7 amp PSU I got off of fleabay is actually doing a better job powering up the board.
Any idea why it's not powering it up? Can't be because of the minimum load requirement.
Last edited by Sunder on September 10th, 2020, 1:18 am, edited 1 time in total.
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zak
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Re: Meanwell RT-125A

Post by zak »

Is there a 110/220v switch?
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RMRM
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Re: Meanwell RT-125A

Post by RMRM »

Be aware that those units only work under a load. You must connect a PCB to it in order to "power it up" and get an actual measurement.
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nem
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Re: Meanwell RT-125A

Post by nem »

I have two of them. I bought them years ago and I haven't had any issues.

You could put additional load on the other rails to see if it performs better.

Anyway, the PSU that I would go for now is the RT-85A. Seems to work with everything so far, even stuff that consumes very little power like the 1-slot MVS. It's 8A on the +5V rail, so plenty enough for everything.
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Re: Meanwell RT-125A

Post by Sunder »

nem wrote:
September 9th, 2020, 10:43 am
I have two of them. I bought them years ago and I haven't had any issues.

You could put additional load on the other rails to see if it performs better.

Anyway, the PSU that I would go for now is the RT-85A. Seems to work with everything so far, even stuff that consumes very little power like the 1-slot MVS. It's 8A on the +5V rail, so plenty enough for everything.
I did put them under load. Hence why we're here. I can't even get past 4.5 v on them on the MVS 4 slot.
I ALSO have 3 of those RT-85As.
I just cant get them to work.
Any tips You guys can give? Kind of at a loss here.

PS: reason why I have so many is because I'm kind of an idiot who plans on building a few more arcade cabinets. :lol:
Last edited by Sunder on September 10th, 2020, 1:17 am, edited 1 time in total.
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RMRM
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Re: Meanwell RT-125A

Post by RMRM »

I recently started using one with no problems so far.

BUT, with at least one PCB i've tried (can't remember which) it could only reach like 4.9v or something like that. Which i find strange for a 12A power supply :problem:

EDIT: maybe a potentiometer change could fix the problem?? Are they somehow "limited"?
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Re: Meanwell RT-125A

Post by nem »

I don't think there's any way to limit them. According to the data sheet the voltage range is from 4.75V to 5.5V

https://www.meanwell-web.com/content/fi ... 5-spec.pdf
Sunder wrote:
September 10th, 2020, 1:16 am
I ALSO have 3 of those RT-85As.
And you have the same issue with those?

Where are you measuring voltages from? The PCB end? Are you sure your wiring is sufficient? It could be the result of voltage drop.

Also, make sure whatever you're using to measure voltage actually gives accurate readings.
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Re: Meanwell RT-125A

Post by Sunder »

Haha yes, in all of those. I mean I just used 5 different MW PSUs on my MVS 4 Slot.
All which gave readings lower than 4.5v even with the voltage pot cranked all the way up, which in turn would not make the board run. Something is up. I mean it can't ALL be bad potentiometers on all the PSUs right?
And yes the board works as I mentioned up there. :lol:
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Re: Meanwell RT-125A

Post by nem »

Sunder wrote:
September 10th, 2020, 11:13 am
I mean it can't ALL be bad potentiometers on all the PSUs right?
Right.

Again, where are you measuring from? If it's at the jamma connector, then what is the voltage at the PSU? If you're measuring from the PSU, double check that your multimeter is actually OK.

Something's off.
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Re: Meanwell RT-125A

Post by geotrig »

it may be but from sunders description it sound like even at the jamma edge it not going over 4.5 v " awhich in turn would not make the board run"
Image

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Re: Meanwell RT-125A

Post by pubjoe »

I apologise for this...
RMRM wrote:
September 10th, 2020, 8:32 am
it could only reach like 4.9v
It meant well.
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Re: Meanwell RT-125A

Post by Sunder »

Yeah I'm seriously at a loss here. Is the MVS 4 Slot power consumption a little quirky, quirky enough that it screws up with whatever failsafe measure the Meanwell has (if it has one)?

And nem, by the way yeah I measured it from the board itself with my DMM, which works fine, but that isn't really the point. The maximum power output I can get off the 5v line with the pot cranked all the way up was 4.5v when under load by the MVS 4 Slot.
On both the 85A and 125A.

pubjoe: :lol:
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Re: Meanwell RT-125A

Post by grantspain »

its only 12amps on the +5, you would want at least 15amps
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Re: Meanwell RT-125A

Post by zak »

The 125A gave me nothing but trouble.

This has served me well on 4 cabs:

https://www.ebay.co.uk/itm/Prima-Black- ... 2749.l2649
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Re: Meanwell RT-125A

Post by nem »

Sunder wrote:
September 11th, 2020, 9:27 am
And nem, by the way yeah I measured it from the board itself with my DMM, which works fine, but that isn't really the point.
Can you please measure the voltage from the PSU? One meter lead on the screw terminal for GND, the other on +5V.

grantspain wrote:
September 11th, 2020, 10:20 am
its only 12amps on the +5, you would want at least 15amps
75W is a lot

https://wiki.arcadeotaku.com/w/PCB_Power_Consumption

For the record, I run a 4-slot with a 8A +5V PSU. No issues.
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Re: Meanwell RT-125A

Post by Sunder »

nem wrote:
September 11th, 2020, 11:08 am
Sunder wrote:
September 11th, 2020, 9:27 am
And nem, by the way yeah I measured it from the board itself with my DMM, which works fine, but that isn't really the point.
Can you please measure the voltage from the PSU? One meter lead on the screw terminal for GND, the other on +5V.
On all 5 of them?
Yeah I don't think the amperage of the PSU is an issue either. The MVS 4 Slot is currently running off that dinky 7amp Chinesium power supply.
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Re: Meanwell RT-125A

Post by cools »

Could you post some pictures of the wiring - how the MW is connected and the JAMMA end?
Image
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Re: Meanwell RT-125A

Post by nem »

Sunder wrote:
September 11th, 2020, 1:43 pm
On all 5 of them?
Any is fine.
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