SoliForum - 3D Printing Community — SD2 Heat Pad Problem

Re: SD2 Heat Pad Problem

2015-10-08T00:45:04Z

Weeellll - I cracked down and ordered a Supernight 360W. Tried 2 ATX P/S. The first one I tried before I started, and it worked OK. My bad - didn't try again til I was done... - no go. (most of 1 day down!). Started again with another ATX P/S. This time checked it at each stage of the assembly. Found one of the Size M connectors I bought was shorted - the last step of my assembly (Murphy sez so). My set up is a little weird. The printer sits on a small stand I built. Under the printer are the Filament spool, and under all - hidden are/were the power supplies. So I can run it all, there are switches for the mains, fans, and the 5V USB power (two machines Mac & Win8.1 one USB plug, have to disconnect from one to get to the other). There are 3 M Size connectors so I can separate the printer from the stand. Make sense? Pics later if I get it working.
Had it going - printer & fans fired up OK, RH saw all. Checked the build plate, and it was untouchable by hand in less than a minute - without turning it on in RH. Checked all connections including the SSR, following some of Ward's old diagrams found in a search, & I think it was OK. Concluded it must have something to do with me only using a couple of 12V leads from the ATX box, and leaving the others capped, but uncut, or I have made a simple connection mistake.
Kinda tired of scooching with it for now. We'll start again next week with the new P/S. Pics to follow to explain it all.

Re: SD2 Heat Pad Problem

2015-09-26T12:02:17Z

From another thread...
"Ok, so this is weird, bizarre even, I place my meter leads to the output pins on the board with bed heater off: I get what I expected 0v across the pins and a 12V potential between each pin & ground. Next I turned bed heater on in RH. and I measure again. - Guess what? I get 12V across the pins and my bed is heating! I don't see any difference in RH or my board but I'm up & running again, the best I can figure is a loose connection, But i'm still going to upgrade, I'm just glad I have a working board again."

I bought the rumba board, I'll let you know how the upgrade went.

Re: SD2 Heat Pad Problem

2015-09-25T18:28:26Z

lueman wrote:

Ok, my FET is fine, so I pulled out my $$$ meter and I get 1.6 ohm on the bed heater, yet my bed doesn't heat any ideas?

when you plug it directly into a PSU does it heat? Use the thermistor to measure the temp--use another PSU besides your printer's so you can open it up in RH

Re: SD2 Heat Pad Problem

2015-09-25T18:20:58Z

Let me know if you end up going with the DC relay and I can probably whip up a quick diagram if needed. You will need a PSU with a solid 30 amps, the common 3D printer PSU that comes from amazon works well.

Re: SD2 Heat Pad Problem

2015-09-24T13:17:15Z

lueman wrote:

Yeah, I get that but when I ran a ohm check on the FETs I got 26MOHMin one direction and a low in the other (Top pin) and high- high on the bottom pin, so it didn't look shorted, I was just wondering if I put a voltmeter on the sink-to-ground or from one of the pins going to the heater bed, what might be the voltage.

Ok dumb question! It's a 12V heater so to answer myself it's 12V!

Re: SD2 Heat Pad Problem

2015-09-23T22:13:39Z

Ok, my FET is fine, so I pulled out my $$$ meter and I get 1.6 ohm on the bed heater, yet my bed doesn't heat any ideas?

Re: SD2 Heat Pad Problem

2015-09-23T21:04:14Z

Your FET is fine.

Re: SD2 Heat Pad Problem

2015-09-23T20:04:10Z

Yeah, I get that but when I ran a ohm check on the FETs I got 26MOHMin one direction and a low in the other (Top pin) and high- high on the bottom pin, so it didn't look shorted, I was just wondering if I put a voltmeter on the sink-to-ground or from one of the pins going to the heater bed, what might be the voltage.

Re: SD2 Heat Pad Problem

2015-09-23T19:20:57Z

lueman wrote:

We've been testing the heater pad, but what about the chips how do we test those voltages? I'm assuming NPN?? the temp graph lists 100% output but how do we know the chip is getting current?

FETs either fail completely or not at all. You can test voltage on the heated bed terminals if you like, though.

Re: SD2 Heat Pad Problem

2015-09-23T19:16:12Z

Which "Chips" are you referring too?

Re: SD2 Heat Pad Problem

2015-09-23T19:12:02Z

We've been testing the heater pad, but what about the chips how do we test those voltages? I'm assuming NPN?? the temp graph lists 100% output but how do we know the chip is getting current?

Re: SD2 Heat Pad Problem

2015-09-23T01:55:52Z

SD3/4 is 2x the bed area, and in my experience around twice the wattage.

Re: SD2 Heat Pad Problem

2015-09-23T01:40:16Z

elmoret wrote:

jagowilson wrote:
3.6 ohms is far too high. it should be around 1.3 ohms (10Amp heater) but cheaper multimeters may read it as high as 2. Looks like some of the traces inside may be damaged.
SD2 didn't have a 10 amp heater, you wish! The power supply was only good for 8 amps (100 watts). The bed was 50 watts, which is right on with the measurement above after considering the poor accuracy cheap multimeters have at low resistances.

Oh, I didn't notice SD2 ... Maybe I'm even remembering mine wrong and the measurement I'm remembering is from a printer at the university.

EDIT: Solidoodle site says 1.9 Ohms for an SD3/4, but they do not indicate if this measured hot or cold. Guess I was close, if not the wrong machine
http://wiki.solidoodle.com/multimeter-testing

Re: SD2 Heat Pad Problem

2015-09-22T21:58:57Z

http://www.mouser.com/ProductDetail/Omr … tXPM4S0%3d

Please don't buy the eBay clones, they are prone to failing on which is a significant hazard.

Re: SD2 Heat Pad Problem

2015-09-22T21:27:38Z

Rather than fry anything else, I've ordered the heat pad MDR mentioned above, and I'm on the search for a 12V SSR. I'm also working on a 350W computer PS to rewire it to my wants. It has 2 17A 12V rails, so I should be able to use one for the board and fans, and one for the SSR controlled heater. If that aint enough, I could put a second computer PS in it, but I believe 700W would be a little much.... I've been using 2 SD PS, the one that came with the unheated bed for the fans, and the 'upgraded' one for the machine.
While checking to find the polarity of the heater output plug, the meter read 12+ VDC, so I think the board is still good. Besides, as I said above, if the Temp Curve screen is accurate, I am getting 100% heat pad power.

We'll see...