1 Topic by Ski52

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Topic: SD2 Heat Pad Problem

Things were going fine, printed some stuff for SHMBO, and started printing some stuff for Christmas (tried to get a jump).
This morning, cranked it up, or tried to, and noticed the heat pad will go to 55 - 60 then start cooling off - slowly - slower than if I manually turned it off.  Checked the connections - seem OK.  The temp curve graph shows 100% power being applied. 

Spoke too soon...
This last time, just now, I tried turning it on, and it won't heat at all.  Seems like whatever was dying has gone belly up.
Suggestions on how to go about repair?

Thanx

Ski

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2 Reply by jagowilson

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Re: SD2 Heat Pad Problem

What does the resistance measure?

3 Reply by Ski52

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Re: SD2 Heat Pad Problem

I'll hafta check - going to Dr's, be back later.

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4 Reply by mdrVB6

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Re: SD2 Heat Pad Problem

I can't help you with how to fix it, but I bought one of these in case mine eventually fails:

http://www.ebay.com/itm/Solidoodle-2-he … 2ca1f50fb8

It's a DC heat pad that will require a separate relay.  I have an upgraded PSU that I plan on using for the heat bed, and just run the main board from the stock PSU, which should be adequate if it isn't also powering a heat bed.  Thankfully mine has not yet died and actually works pretty good with the upgraded PSU but this is what I'm going to when it eventually dies.  Just an idea.

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5 Reply by Ski52

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Re: SD2 Heat Pad Problem

Jag - the resistance is 3.6 ohms - little low?
MDR - just ordered one.  Weather this one is still good or not.  Ironically, it's the same company that I had found on a Google search and had e-mailed on Saturday. 
I have a few computer power supplies - 350 - 400W.  Any diagrams posted on how to wire one using a relay, or is it enough to just go directly and replace the OEM PS?
Open for suggestions.

Thanx
Ski

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6 Reply by lueman

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Re: SD2 Heat Pad Problem

Ski52 wrote:

Jag - the resistance is 3.6 ohms - little low?
MDR - just ordered one.  Weather this one is still good or not.  Ironically, it's the same company that I had found on a Google search and had e-mailed on Saturday. 
I have a few computer power supplies - 350 - 400W.  Any diagrams posted on how to wire one using a relay, or is it enough to just go directly and replace the OEM PS?
Open for suggestions.

Thanx
Ski

funny exactly same thing happened to me. the 3.6 ohms seems right to me the heater reads about 5-6 ohms. I even went so far as to switch the bed heater with the heater block , I kept my temps way low just for safety, sure enough the bed started heating as soon as I clicked the heater block icon so I turned it off when I went to click the bed heater which should have started the heater block in this case- I got nothin'! also found some charring around the bed connector (never a good sign). I'm thinking of replacing the board but about $200.00 for a sd4 is hard on my pocket for now.

SD4 with E3D V6.

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7 Reply by jagowilson (edited by jagowilson 2015-09-22 18:52:06)

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Re: SD2 Heat Pad Problem

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.

8 Reply by lueman

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Re: SD2 Heat Pad Problem

Well on my cheapo meter it reads about 3.6 ohms, but again I switched the heater block with the bed and I could get a temp rise from the heater bed so I'm pretty sure the bed is ok and in my case at least the problem is in the board. I thought the bed traces were a continuous matrix so if I had an open trace the bed wouldn't heat at all, but I leave it up to the experts to correct me.-

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9 Reply by elmoret

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Re: SD2 Heat Pad Problem

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.

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10 Reply by Ski52

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Re: SD2 Heat Pad Problem

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...

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11 Reply by elmoret

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Re: SD2 Heat Pad Problem

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.

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12 Reply by jagowilson (edited by jagowilson 2015-09-23 01:43:02)

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Re: SD2 Heat Pad Problem

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 ... wink 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 tongue
http://wiki.solidoodle.com/multimeter-testing

13 Reply by elmoret

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Re: SD2 Heat Pad Problem

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

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14 Reply by lueman

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Re: SD2 Heat Pad Problem

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?

SD4 with E3D V6.

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15 Reply by wardjr

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Re: SD2 Heat Pad Problem

Which "Chips" are you referring too?

Printit Industries Model 8.10 fully enclosed CoreXY, Chamber heat
3-SD3's & a Workbench all fully enclosed, RH-Slic3r Win7pro, E3D V6, Volcano & Cyclops Hot End
SSR/500W AC Heated Glass Bed, Linear bearings on SS rods. Direct Drive Y-axis, BulldogXL
Thanks to all for your contributions

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16 Reply by elmoret

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Re: SD2 Heat Pad Problem

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.

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17 Reply by lueman

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Re: SD2 Heat Pad Problem

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.

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18 Reply by elmoret

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Re: SD2 Heat Pad Problem

Your FET is fine.

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19 Reply by lueman (edited by lueman 2015-09-24 13:14:51)

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Re: SD2 Heat Pad Problem

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?

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20 Reply by lueman

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Re: SD2 Heat Pad Problem

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!

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21 Reply by mdrVB6

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Re: SD2 Heat Pad Problem

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.

SD4 w/ RUMBA, E3D Volcano, all bearings, glass bed

22 Reply by jagowilson

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Re: SD2 Heat Pad Problem

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

23 Reply by lueman

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Re: SD2 Heat Pad Problem

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.

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24 Reply by Ski52

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Re: SD2 Heat Pad Problem

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.

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