Meanwell NES Schematic..almost complete

[neptronix]

AARGH... This single shunt is hyper sensitive
I got it down to 11a, then ~7a. The screech is the same volume and tone.

Tried to add some solder to the shunt when it was putting out 7A and the thing just fell apart.
Yes, my shunt is a razor thin bridge of solder at this point, basically.

So i threw a tiny strand of copper ( about half the diameter of a ballpoint pen's tip, maybe 7mm in length ) between the gaping chasm and i'm back up to 13A; roughly 122% current.

anyone interested in a meanwell NES..

[NeilP]

Should have gone with the mod route as suggested by Cor...far more controllable. This shunt method is so rough. as you have both found out

[amigafan2003]

Yup - my current is rock solid - stays at 7.7a until the pack gets to 49v then ramps down steadily to zero between 49v and cut off at 50v.

[NeilP]

Ah sorry, as Netpronix has found out

[amigafan2003]

Should have gone with the mod route as suggested by Cor...far more controllable. This shunt method is so rough. as you have both found out

It's working fine for me.

Ah sorry, as Netpronix has found out

Why sorry?

[neptronix]

hrm... so.. can i do the 'add a resistor' mod without cutting the trace? would it work?

<-- clearly doesn't know crap about electronics, so bear with me here.

[NeilP]

Should have gone with the mod route as suggested by Cor...far more controllable. This shunt method is so rough. as you have both found out

It's working fine for me.

Ah sorry, as Netpronix has found out

Why sorry?

"Sorry" because I was apologising for included you in the bit that said " You both found out" , when I after realised that you had said you were happy with yours working


David, ...not sure about the cutting the track. I do not have a supply here to look at. but it seems fairly straight forward. I am not sure if the resistor R134 is a small surface mount component, or a proper component.

If it is a traditional full size component, then instead of cutting the track, you could instead, unsolder one end of it, and conect the adjustment pot or extra resistor to that.


Cheers

Neil

[cor]

I posted pics some time ago to show that
R134 is SMT
where i suggest to cut the trace
so you can solder wires to adjacent pads

[neptronix]

Guys.
Sorry i was just apprehensive to do your current mod. I've never done such a modification to something that's plugged into AC current and being a total electronics imbecile, it made me nervous to do so.

Now i have nothing to lose..



I bought a 1K resistor and i am wondering if i am understanding things correctly.. is this where i insert the resistor for a constant 25% reduction of current.. and do i have to cut the trace in the middle?

[NeilP]

Yes, that is where you have to cut the trace.

Often best way to cut a trace is to use a drill bit, just the size of the trace to cut, and spin it gently on the trace with your fingers or in a holder, not using a drill. Or carefully with a craft knife..but that way can result in slippage, and more than you bargained for getting cut.

Look at the pic again.


See where Cor has the word R134 and the shorter of the two lines below it, that is the trace to cut, and then the resistor goes across the gap where the cut it...So yes, it looks to be correct.




What happened to the shunt mod? Where has that left it in relation to current. ? I believe if you have changed the shunt value, now, by shaving bits off it, that is going to affect what value of resistor is going to be needed here.


I understand your concern about working n something like this for the first time though.

[neptronix]

What really confused me was the 'r134' right next to the arrow, indicating that the drawing of what looks like a resistor was r134.

Also i don't understand why there is a line coming from the transformer straight to the shr1.. or why a line coming from the transformer straight to anything is there. it made me nervous to even go there. I thought maybe the resistor went there but i was confused.

For the resistor mod, going off what he wrote, it sounded like you took the value of r134 and increased it by 1K to get a 25% reduction in current.
That's why i'm wondering if i run the resistor in parallel or series ( in series you have to cut the trace though, right? )

Maybe i should PM cor just to be 100% sure?

for the shunt mod, i adjusted the length of the copper and the amount of the solder on it to be approximately the same value as the original. Anything less than the original value makes it screech like crazy. Anything more than the original value produces the same amount of current as the original, which is really weird. The shunts must work very differently here.

[NeilP]

What really confused me was the 'r134' right next to the arrow, indicating that the drawing of what looks like a resistor was r134.

I can see that looks weird,. Maybe the points Cor has shown the resistor connected to are just other points on the board, that are common electrically to where it (R143) needs to go, and it is just that not actually putting it 'either side' of the cut trace makes it seem odd

Also i don't understand why there is a line coming from the transformer straight to the shr1.. or why a line coming from the transformer straight to anything is there. it made me nervous to even go there. I thought maybe the resistor went there but i was confused.

Think that black wire is there merely because Cor's board is mine that I zapped, doing an earlier mod. I could not repair it so passed it on to Cor. I think this black wire is something to do with either his mods to get it to work, or possibly a broken trace on the board , that was 'fixed' at the factory like that in order to make it work.

For the resistor mod, going off what he wrote, it sounded like you took the value of r134 and increased it by 1K to get a 25% reduction in current.

Exactly.. go from his drawing and compare to your board
http://i1236.photobucket.com/albums/ff4 ... ematic.jpg

That's why i'm wondering if i run the resistor in parallel or series ( in series you have to cut the trace though, right? )

Series with R134, so cut the trace and put the new resistor across the cut at two convenient points.

Maybe i should PM cor just to be 100% sure?

Can't harm. although as he had said previously he is busy..and if he is not hear responding, it is usually because he is snowed under with other stuff

for the shunt mod, i adjusted the length of the copper and the amount of the solder on it to be approximately the same value as the original. Anything less than the original value makes it screech like crazy. Anything more than the original value produces the same amount of current as the original, which is really weird. The shunts must work very differently here.

Cant remember..but only one shunt right? small change in that is going to make big difference. it is only in the milli Ohm range anyway, so cutting or adding to it can make a big difference.

I am thinking that since you have done a shunt mod, and although managed to rectify it to somewhere near normal,you may need to experiment with different values of additional resistors to get your current where you want it. Maybe the pot mod might be better.

No more replies for a few hrs now.

have started playing with dd-wrt firmware hacks to routers..trying to make a wireless bridge and antenna setup to span 500 meter of field to get wifi from house to workshop, so off to do that now.

Good luck...PS if it goes wrong..send it to Cor to give him another to experiment with like I did

[neptronix]

Thank you very much for your help so far, Neil. I will annoy him via PM for good measure so that nothing blows up Good luck with the WRT hacks, sounds fun.

I will use the dremel forr the 8th time to adjust the shunt if need be, LOL. I have 5 fans on top so even if i am running a bit over the rated power, it should live.

Will report back with the results.

[neptronix]

BLARGH.
Cut the trace.. made sure there was no continuity..
Soldered a 1K resistor from the end of the SMD to the svr1 point....



Made sure that the little nick in the other trace was OK and that i had not shorted anything else.. check!

0 amp output when connected to the battery!
OK.. so then i thought.. maybe i need a lower resistance value.. so i removed the 1K resistor and soldered a 10K 15 turn potentiometer in it's place.
Same problem from 0.0K to 10K No output.

Aahh.. but the problem was actually the battery.. whoops. One of the solder joints is weak on a cell..

So i switched batteries.

Set the trim pot to 0.0K.
Connect to battery.. 12 amps output as usual. No screeching.
Turned the resistance slowly up.. suddenly, i get 17 amp output

Immediately turn it down.. 12 amps... and screeching! So i unplug it immediately.

Well... this was a waste of time.. and money.. but mostly time..

[bobale]

I know you know your way around MWs, but have you tried unplugging the fan to see will it stop screeching then?

[neptronix]

I already did that. Previously, i had a switch on the fan mod, so that i could turn it on and off while i was trying to do the shunt mod. It didn't make any difference in current ( like it did with the old meanwells ). It didn't make any difference in screeching at various degrees of shunt adjustment either.

[NeilP]

That is a bugger.
At least it is easy to go back to original, easy to bridge that cut on the track

[bobale]

It didn't make any difference in screeching at various degrees of shunt adjustment either.

Bugger indeed.

[NeilP]

I am thinking maybe a multi turn pot may work better
Just wondering if the system swings a big and takes a while to settle down, also maybe needing only small resistance change to adjust current
A single turn pot, not being so precise makes control difficult, small resistance changes from a multi turn pot may give better results

[neptronix]

It was a 10K, 15 turn pot actually, i bought it thinking of that sensitivity issue.

There seemed to be basically a threshold with no real middle ground.. either 12-some amps, or 17-some amps. Kinda weird. That was within a range of maybe 5 turns.

You know. If anyone here wants it.. it still functions. And i haven't mangled it too bad. Throw me an offer. I need $ to go towards something greater.

[NeilP]

Oh, well, if you already have multi turn then it really is now one for Cor.

I'd take it if we were closer, but I have gone over to the BMS alloy shell chargers now. so much less hassle, a ready to go plug and play solution for higher volts.

Just wait for Cor to chime in now with suggestions

[fechter]

One of my Mini Limiter boards would probably work with it.

[neptronix]

One of my Mini Limiter boards would probably work with it.

$15 plus shipping and you have a test unit to find out. lol. I'm done screwing with it.

[shawn_1976]

I know this is an old post. But back in april I had bought a couple of the NES power supplies not know that the board would be different inside. After frying a couple I think we got it figured out. We have moded about 12 so far since then. Everything seem to be fine. They get used daily with no problems. If anyone is still looking to do this let me know.

[NeilP]

Don't be so cryptic, just tell us what you did, am keen to know the mod you used