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WARNING Do not buy these PCB HBP's

Posted by Dust

Dust

WARNING Do not buy these PCB HBP's
September 25, 2013 05:48AM

Admin
Registered: 13 years ago
Posts: 7,002

[www.aliexpress.com]

They have the plated threw holes directly to the sold copper layer on the other side.

Instant short!

Can be fixed by drilling out the plate threw holes or cutting a insulation gap around the holes on the back.

Have found 4 cases of this so far....

Edited 1 time(s). Last edit at 09/25/2013 05:51AM by Dust.

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Rigor_M

Re: WARNING Do not buy these PCB HBP's
October 09, 2013 10:44AM

Registered: 10 years ago
Posts: 98

Are you talking about the leads threw holes ?

because the one for holding the bed look like they dont have copper around them winking smiley

Looks like what I have and I have trouble with my heatbed.. (when I turn the power on for the bed, the power supply trips its protection)
What I discovered (with your photo and my version) is, the resistor on the MK2a is on the positive (+) side. should be on the negative (-) one.

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Rigor_M

Re: WARNING Do not buy these PCB HBP's
October 09, 2013 05:51PM

Registered: 10 years ago
Posts: 98

Well, i drilled out the 2 "vias that should not be" on my bed and sure enough it work.. I can raise the temp to 110C without triggering the power supply's protection.

Thanks for the info grinning smiley

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Dust

Re: WARNING Do not buy these PCB HBP's
October 10, 2013 12:36AM

Admin
Registered: 13 years ago
Posts: 7,002

Can you advise as to your supplier?

I suspect there are more than one supplier of these bad boards.

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nophead

Re: WARNING Do not buy these PCB HBP's
October 10, 2013 07:21AM

Admin
Registered: 17 years ago
Posts: 7,879

If they are plated I would expect the resistance to be about half what it should be. I.e. 0.6R instead of 1.2R.

The board is designed to not be plated because when plated through holes are electroplated the whole of the outside copper layers are also plated. The thickness is not as well controlled as the thickness of the original copper foils so to get accurate resistances the plating step is missed out.

[www.hydraraptor.blogspot.com]

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Rigor_M

Re: WARNING Do not buy these PCB HBP's
October 10, 2013 07:50AM

Registered: 10 years ago
Posts: 98

@Dust : On ebay, elect_mall2012.. here is my buy here if you look closely, you will see a copy n' paste of the aliexpress you give here. that is what tip me off ;-)

@nophead: the final resistance is 1.4 Ohms stable.. so I would guess its in the ball park mark. before i drilled the holes, I had 0,4 ohms.. pretty low ;-)