Meanwell clone- AD488.3-400W power supply mods

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Meanwell clone- AD488.3-400W power supply mods

Post by fechter » Dec 30 2015 1:20pm

I found this one on eBay for around $22 usd. It's very similar to the Meanwell S-350 but rated for 400W.
http://www.ebay.com/itm/110-220V-to-DC- ... Sw4HVWCfUo

Nameplate label (sorry about tearing it up where it covered the screw):
Img_3656.jpg
Img_3656.jpg (62.75 KiB) Viewed 4423 times
Board Top 2.jpg
Board Top 2.jpg (129.32 KiB) Viewed 4422 times

Since I want to use it for charging my 16s A123 pack (or a 14s Li-ion pack), the maximum voltage needs to be around 59v.
With the stock adjustment, I could only get about 52v. By placing a 10k resistor across R40, I'm able to get it over 60v. (warning: the output caps are rated for 63v, so not a good idea to go past this).

This model is pretty crude and does not have a secondary OVP circuit like the Meanwell S-350. This makes tweaking the voltage higher easy, as I don't need to mess with any zener diodes.
Img_3654.jpg
Img_3654.jpg (79.98 KiB) Viewed 4423 times
Next step is to make the current limit adjustable downward. Stock current limit is around 8.3A, which will be too high to run continuously. By placing a 10k trimmer pot across R35, the current limit can be adjusted. I used a pair of wires to the pot, which is mounted near the voltage adjuster for easy access.
Img_3655.jpg
Img_3655.jpg (95 KiB) Viewed 4423 times
Both mods can be done without removing the board from the frame.

The first time I turned it on, it made a really bad burning smell and I thought something fried in there. I traced it down to the inrush current limiter NTC, which was getting pretty hot, but this is normal. I guess there was some oily, stinky residue on the NTC part that gave off a bad smell. The smell dissipated after a while and the NTC seems to work fine.

While I had the board out, I touched up a bunch of sketchy solder joints and trimmed some excessively long lead wires. I think it will help the reliability quite a bit.

The fan runs continuously but is very quiet compared to my old S-350.
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Re: Meanwell clone- AD488.3-400W power supply mods

Post by agniusm » Dec 30 2015 3:01pm

So its sort of manual charger where you have to dial CC at the end of charge cycle?

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Re: Meanwell clone- AD488.3-400W power supply mods

Post by fechter » Dec 30 2015 5:52pm

When it starts out, it runs CC (I have it set at 5A) and it stays there until the pack voltage gets close to the CV setting, where it starts to drop. It will eventually drop to near zero at the CV setting if I let it run long enough. I have another circuit that cuts it off at end of charge.

Its just like all the other Meanwell supplies.

The reason for the current adjustment mod is simply to lower it enough so the thing doesn't overheat when running for hours. You could use a fixed resistor.
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Re: Meanwell clone- AD488.3-400W power supply mods

Post by MrDude_1 » Dec 31 2015 9:18am

What kind of heatsinking does it use? Or is it just bolted to the case as a heatsink?
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Re: Meanwell clone- AD488.3-400W power supply mods

Post by fechter » Dec 31 2015 1:59pm

MrDude_1 wrote:What kind of heatsinking does it use? Or is it just bolted to the case as a heatsink?
The case is the heatsink. I'll post more pics of the completed unit after my camera gets recharged.
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Re: Meanwell clone- AD488.3-400W power supply mods

Post by fechter » Jan 03 2016 6:33pm

Here's the overall with the volt/amp meter attached. It's the same size as a S-350.
100_0516.jpg
100_0516.jpg (116.76 KiB) Viewed 4321 times
Current adjusting pot:
100_0515.jpg
100_0515.jpg (82.95 KiB) Viewed 4321 times
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Re: Meanwell clone- AD488.3-400W power supply mods

Post by Mammalian04 » Jan 04 2016 2:30am

Very nice Fechter! I'll be picking one of these up for my Adaptto.

This is what I'll be ordering if I have your instructions correct above:
10k Trimmer Pot

1/4w 10k ohm resistor

Just curious, how did you know what changes to make for the Amperage pot and voltage change? Is this just something that EEs can see when they see a circuit board?

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Re: Meanwell clone- AD488.3-400W power supply mods

Post by fechter » Jan 09 2016 11:45am

Those resistors should work fine.

I've reverse engineered enough of these to know the basic circuit. Most of them use the same KA7500 controller chip. Seems like every model has a slightly different layout so you have to trace the circuit to find the right spots.
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Re: Meanwell clone- AD488.3-400W power supply mods

Post by Mammalian04 » Jan 09 2016 11:57am

Thanks Fechter. I suppose if you know what you are looking it it seems more simple!

Thanks again for the help.

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Re: Meanwell clone- AD488.3-400W power supply mods

Post by DrkAngel » Jan 16 2016 9:54am

Nice find and great mod diagnosis.

Just throwing in my 2¢ to bookmark thread.

Ordering a few.
Will test and document for 7s (29.4 x 13.6A), 9s (37.8V x 10A) and 10s (42V x 9.5A) modability
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Re: Meanwell clone- AD488.3-400W power supply mods

Post by kje » Jan 26 2016 9:21am

fechter wrote:I found this one on eBay for around $22 usd. It's very similar to the Meanwell S-350 but rated for 400W.
http://www.ebay.com/itm/110-220V-to-DC- ... Sw4HVWCfUo

Nameplate label (sorry about tearing it up where it covered the screw):
Img_3656.jpg
Board Top 2.jpg

Since I want to use it for charging my 16s A123 pack (or a 14s Li-ion pack), the maximum voltage needs to be around 59v.
With the stock adjustment, I could only get about 52v. By placing a 10k resistor across R40, I'm able to get it over 60v. (warning: the output caps are rated for 63v, so not a good idea to go past this).

This model is pretty crude and does not have a secondary OVP circuit like the Meanwell S-350. This makes tweaking the voltage higher easy, as I don't need to mess with any zener diodes.
Img_3654.jpg
Next step is to make the current limit adjustable downward. Stock current limit is around 8.3A, which will be too high to run continuously. By placing a 10k trimmer pot across R35, the current limit can be adjusted. I used a pair of wires to the pot, which is mounted near the voltage adjuster for easy access.
Img_3655.jpg
Both mods can be done without removing the board from the frame.

The first time I turned it on, it made a really bad burning smell and I thought something fried in there. I traced it down to the inrush current limiter NTC, which was getting pretty hot, but this is normal. I guess there was some oily, stinky residue on the NTC part that gave off a bad smell. The smell dissipated after a while and the NTC seems to work fine.

While I had the board out, I touched up a bunch of sketchy solder joints and trimmed some excessively long lead wires. I think it will help the reliability quite a bit.

The fan runs continuously but is very quiet compared to my old S-350.
Can I use this to limit the current? ☺
http://www.ebay.com/itm/251877265728?_t ... EBIDX%3AIT

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Re: Meanwell clone- AD488.3-400W power supply mods

Post by DrkAngel » Jan 28 2016 9:50am

fechter wrote: The fan runs continuously but is very quiet compared to my old S-350.
I prefer a constant run fan, as opposed to a fan that cycles at some heat thresholds.
Temperature fluctuations cause expansions-contractions that eventually produce failures!

Ideal is a fan circuit that varies speed in response to actual temperature.
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Re: Meanwell clone- AD488.3-400W power supply mods

Post by fechter » Jan 28 2016 10:43pm

kje wrote: Can I use this to limit the current? ☺
http://www.ebay.com/itm/251877265728?_t ... EBIDX%3AIT
Yes, those should work fine.
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Re: Meanwell clone- AD488.3-400W power supply mods

Post by kje » Feb 01 2016 8:49am

fechter wrote:
kje wrote: Can I use this to limit the current? ☺
http://www.ebay.com/itm/251877265728?_t ... EBIDX%3AIT
Yes, those should work fine.
Thank you.
How did you find out where to place the 10k trimmer pot so the current limit can be adjusted?

I wonder if I can do the same on my 350w power supply...

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Re: Meanwell clone- AD488.3-400W power supply mods

Post by izeman » Feb 01 2016 11:50am

I wish i could find a way to LOWER voltage of mine. Somehow there's a limit that it won't go under, no matter what resistor you choose.

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Re: Meanwell clone- AD488.3-400W power supply mods

Post by MrDude_1 » Feb 01 2016 1:21pm

izeman wrote:I wish i could find a way to LOWER voltage of mine. Somehow there's a limit that it won't go under, no matter what resistor you choose.
What voltage are you trying to hit?
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Re: Meanwell clone- AD488.3-400W power supply mods

Post by kje » Feb 01 2016 1:32pm

fechter wrote:
Yes, those should work fine.
I've taken additional picture (look at the attachment under) of underside of circuit board so R35 function might, possibly, have a chance of being determined?
Does R35 in this power supply controls amp output?
file.jpeg
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Re: Meanwell clone- AD488.3-400W power supply mods

Post by izeman » Feb 01 2016 1:36pm

MrDude_1 wrote:
izeman wrote:I wish i could find a way to LOWER voltage of mine. Somehow there's a limit that it won't go under, no matter what resistor you choose.
What voltage are you trying to hit?
As low as it gets. ;) I was hoping for 0-60v.


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Re: Meanwell clone- AD488.3-400W power supply mods

Post by MrDude_1 » Feb 01 2016 1:59pm

izeman wrote:
MrDude_1 wrote:
izeman wrote:I wish i could find a way to LOWER voltage of mine. Somehow there's a limit that it won't go under, no matter what resistor you choose.
What voltage are you trying to hit?
As low as it gets. ;) I was hoping for 0-60v.
With this type of circuit, you can only go so low before it has to cut out. There is no way to get it all the way down to near zero without turning it off. Its not a lab power supply.
What do you need a 0-60v supply for? if its a low amperage lab supply, there are plenty of other cheap options. We use supplies like these to bulk charge batteries, so they only need to sweep within a specific voltage range.
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Re: Meanwell clone- AD488.3-400W power supply mods

Post by fechter » Feb 01 2016 7:44pm

kje wrote:
I wonder if I can do the same on my 350w power supply...
I traced out the circuit and used the datasheet for the controller chip. There's a good chance you can do the same thing with your supply. If you post good pictures of both sides of the board, I might be able to trace it out for you.
izeman wrote:I wish i could find a way to LOWER voltage of mine. Somehow there's a limit that it won't go under, no matter what resistor you choose.
Some of these supplies can only go to about half the rated voltage and some can go to near zero (but will be in discontinuous mode below a point). I need to see both sides of the board to tell which resistor to mess with. In most arrangements, adding resistance in series with the pot will lower the voltage.
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Re: Meanwell clone- AD488.3-400W power supply mods

Post by Hillhater » Feb 01 2016 8:45pm

I have one of these clones that was listed as 0-24 volt variable. (350 W, 17 A max)
In practice it actually runs down to about 6 volts before it becomes unstable(and noisy ?) and all the way up to 30 volts, on the standard "V" adjuster.
There is no current adjustment, so I guess it would theoretically try to feed 17amps at 30 volts, but I have never tried loading it up that much.
Oddly, I have not seen any like this lately on sale.?
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Re: Meanwell clone- AD488.3-400W power supply mods

Post by DrkAngel » Feb 01 2016 9:32pm

Couple years ago I got a 350-48 that adjusted down to single digits ... forget how far ...
No discernible manufacturer or model number.

Look for items with a multi-turn pot ... and take your chances?
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Drink deep, or taste not the Pierian spring:
There, shallow draughts intoxicate the brain,
And drinking largely, sobers us again.

I enjoy enlightening ... and enlivening the spirit of the innovators.

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Re: Meanwell clone- AD488.3-400W power supply mods

Post by fechter » Feb 02 2016 9:19am

The voltage reference for the regulator is 2.5v, so you could theoretically make most of them go this low with a single resistor change. It will not be able to do the full rated current below some higher voltage. The screechy sound happens when it goes discontinuous. This is rough on the output caps. Most of the ones I've tested will be happy down to about half the nominal rated voltage.
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Re: Meanwell clone- AD488.3-400W power supply mods

Post by kje » Feb 05 2016 8:41am

fechter wrote:
kje wrote:
I wonder if I can do the same on my 350w power supply...
I traced out the circuit and used the datasheet for the controller chip. There's a good chance you can do the same thing with your supply. If you post good pictures of both sides of the board, I might be able to trace it out for you.
Here is pictures of both sides of the board. Can you trace it out for me?

Side 1:
file.jpeg
file.jpeg (178.33 KiB) Viewed 1611 times
Side 2:
20160127_114807.jpg

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