Simple Metal Power Connector Cooking

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Simple Metal Power Connector Cooking

Postby Jack Crow » 2018-Jan-Sun-20-Jan

Hi all
Noticed that the power connector for my Simple Metal is starting to suffer from heat stress.
Im going to need to fix this soon.

After the discussion of printer fires here it might be time to re think the power system for this printer.

1-14-2018 002.JPG


In service this connector did not work out on the long run. No blame, it simply a cost point the OEM must meet if they want to stay in business.

Saw this before with Molex style connectors.
Most OEM's crimp the connectors and over time oxygen gets into them, increasing their internal resistance.
That resistance caused heat and that cooked the connector body.
I can no longer trust the pins or the connector.
This problem is not unique to printers, saw it first years ago in high power two way radios.
The only fix is to replace the tired parts. Anything else is simply making excuses..

Here is the thinking.
This unit will not ever be part of a fleet.
As the guys here say it has been 'modded'. So be it.
I am not going to be swapping systems or power supply's with others.

So if I upgrade this connection with something a bit more beefy no one will be inconvenienced.

Might as well do a tip to tail on the power system.
Have a couple of power supply's that might do the trick.
One is a converted HP Server power supply. 12 volts at 25 Amps.
May also get a more conventional Meanwell or Lambda switcher in the same range.
The Meanwell PSU I use for the ham radio has been fine.

As for connectors.
From the two way radio side of life, I have a good supply of Molex .093 12 pin connectors, they are good for someplace between 15 and 18 amps.
If soldered rather than crimped, they should work. Yet over time they will oxidize.

Also have expensive experience with Anderson Power Pole Connectors. They are good for 25 amps each.
Four or six points of those will do just fine.

Next time I pull the system down for a maintenance event, I will examine where the cable plugs into the circuit board.
If it shows similar stress off it will come and I will solder the wires directly.

Speaking of wire, that will be improved as well. A significant step up over what the modified PC supply was made with.

So the question now is, anybody else have this issue and what was your fix.

Thanks in advance.
Jack Crow
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Simple Metal Power Connector Cooking

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Re: Simple Metal Power Connector Cooking

Postby RetireeJay » 2018-Jan-Sun-22-Jan

XT60 connectors, heavy gauge wire, and soldered connections! That's what I did for my heat bed: viewtopic.php?f=15&t=2789&p=31652&hilit=power+connector#p31652 (The picture is when I had a Rev D board. The Rev F board uses a terminal strip with screw clamps for the wires going to the heater, no solder required there.)

But that said, I've had no problem with the 6-pin power connection on my Rev F6 board. It's still "original". Millions of computers use this 6-pin connector, so it must not be all that unreliable. I don't know why yours in particular developed high resistance. And BTW, I seem to recall that military research on reliability of connections gives properly crimped connections a score at least as good as soldered connections (although I couldn't quickly Google the reference).

If you want an in-depth discussion of connector reliability, you can look at this: http://www.ieee-holm.org/h2004/h2004antler.pdf
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Re: Simple Metal Power Connector Cooking

Postby Jack Crow » 2018-Jan-Sun-22-Jan

RJ
I do agree with you, if everything is done right, crimps are fairly good.

Like so much in life, there is always some little thing waiting for it's moment to bite us on the butt.

Lots of reasons for crimp connectors to go sour.
No need to rundown the OEM about this.
Most likely these cables are something they purchased and used rather than fabricated in house.
Third world manufacturing, such is life.

Just made a part on the printer and that connector was more warm that I would ever like.
Clearly it hit the end of a service life.

May have to do this update during the week. Unless someone here has a better idea, the Anderson Power Pole connectors are going on.
Also going to reconnect the volt/amps meter I was using. That way I can keep an eye on how the condition of the bed heater in terms of amps draw.

I mentioned an HP server supply. It is sitting on the other bench.
Don't want to use it. The fan I used is down right loud.
Was hoping to give it to one of the radio guys here for a PSU for a workshop or garage station where it would seem quiet next to let's say, an air compressor hammering away.

There is a 29 amp Meanwell unit on Amazon for 41 bucks, that is a bargain for the watts.
Will have to see how the money goes from this weeks paycheck.

On ebay prices for Lambda's are all over the dial.
New / used/ pulls from equipment, and 'don't know's' run from just above this Meanwell to bananas prices.

The Richmond Virginia ham radio club has it's Frostfest in early February.
About three weeks out.
Most likely will find something there for not a lot of dollars.

The price we pay for power.

Keep it sane
Jack Crow aka Radio Mike
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Re: Simple Metal Power Connector Cooking

Postby Mooselake » 2018-Jan-Mon-12-Jan

I've used DeOxit for many years, including on my original rev whatever it is printerboard. Not sure if it's luck and a placebo effect, or it helps, but the power connector still works.

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Re: Simple Metal Power Connector Cooking

Postby Jack Crow » 2018-Jan-Mon-21-Jan

Kirk
At the day job we found out the hard way something about De Oxit (how ever it's spelled).

In a nut shell you have to get the right one.
There are three or four different ones.
One dissolves plastics for sure!

One of my buds found that out on a clients stereo receiver.
The result was not pretty.

Then I found out that the solvent we use for flux removal also ruined the connectors I just installed.
More money, more rework.

So that is the news from Virginia Beach.

Keep it sane
Jack Crow aka Radio Mike
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Re: Simple Metal Power Connector Cooking

Postby Mooselake » 2018-Jan-Tue-14-Jan

There's red, which is the deoxidizer. Blue is the contact protector, it's really called PreservIT. Gold is the super wonder stuff, called "ProGold" and it's described as a connector and contact conditioner. My kit included a small tube of gold, and since none of my contacts have had frizzy hair I can't figure out what I'd use it for.

I bought the kit a long time ago, maybe even pre-Internet, and may have spilled more than I've used (I now screw the top back on as soon as I'm done...). You only need a tiny dab, and if you avoid their included foam swabs it doesn't take very much with the in-bottle brush. Never seen it dissolve plastic, but maybe I'm just lucky, and I'll watch for it. I usually use the red stuff, do the plug/unplug routine a few times, then dab on the blue wonder. If I'm feeling adventurous and hauled out the whole kit instead of just the bottles sometimes I'll put on a droplet of gold just in case it gets humid and things get hairy

Kirk

Edit: I went and read the [ur=http://store.caig.com/s.nl/sc.2/category.292/.f]datasheet[/url], gold prevents hair (they call them dendrites) and is for precious metals. They include copper in that list, guess they've been checking scrap metal prices
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Re: Simple Metal Power Connector Cooking

Postby Jack Crow » 2018-Jan-Sat-16-Jan

HI all
Did something useful today.

I removed the slowly cooking connector and replaced it with Anderson Power Pole style connectors.

Six of them.

Andersons are good because they can be stacked and nested a bunch of different ways.

This is the top view.
I made use of the existing wire work.
Cut off the cooked connector and soldered these in.

1-27-2018 010.JPG


This is the side view of the connector stack.

1-27-2018 011.JPG


That red box to the right is a case I made some time back to hold a current shunt.
Had a Drok meter connected to this thing to see what it was up to.
It would show me when the bed heater had been turned on and such.
I may re install a meter here, so that has been left alone.

The acid test is to measure the voltage drop across the contacts under load.
In this case with the printer working, and the heat bed turned on.

Used the Fluke 8060A meter with the probes pushed into the connector stack.
It's showing a voltage drop across the connection of 570uV or .00057 vdc.
That is very good.

1-27-2018 012.JPG


It would take a long time for these to heat up enough to even warm slightly.

1-27-2018 014.JPG


Real pleased with how this project turned out.
Will be contributing the burned connectors to a great area landfill.

That's the follow up report.

Jack Crow in Virginia Beach.
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Re: Simple Metal Power Connector Cooking

Postby Mooselake » 2018-Jan-Sun-17-Jan

I would have used two connectors and 45A contacts - which only seem to differ in the size of the crimp area. My 45A have a different tinning, and some ridges on the crimp, but they likely came from different sources. They're made from plated/tinned brass and to the MK 1 eyeball don't look to be any thicker.

Powerpoles.jpg


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Re: Simple Metal Power Connector Cooking

Postby Jack Crow » 2018-Jan-Sun-20-Jan

Kirk
I have a similar set up in a plastic divider box.
Did not have any of the big ones so I used a bunch of smaller ones.
Just to get past the problem.
Did not want a failure.
While I had the unit on the bench, inspected the board connections, they seem ok.
Nothing else looked heat stressed.
Back on the air making stuff.

Keep it sane.
Jack Crow
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