1 Topic by Whiteshark

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Topic: Print bed doesn't heat

Hi everyone,

I think the motherboard is dead. After changing the mosfet and the connector, the print bed still doesn´t heat. The print bed is working fine, because i've tested connecting to the extruder pin. What should I do to check the motherboard is working in condition?

Thanks in advance.

Nelson

SD3 Sanguinololu motherboard

Solidoodle 3, Slic3r, ABS

2 Reply by wardjr

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Re: Print bed doesn't heat

Are you receiving any kind of error in R-H such as a "Max Temp" Error?
Maybe a little more information about the original symptoms along with some pictures of your repairs.

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SSR/500W AC Heated Glass Bed, Linear bearings on SS rods. Direct Drive Y-axis, BulldogXL
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3 Reply by Whiteshark

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Re: Print bed doesn't heat

Hi Wardjr,

machine status: heating bed
bed temperature: 18,6ºC (doesn't increase)

this is the second time that happens , then you see the patch made the first photograph. This time , I bought connectors and mosfets , from what I read in the forum , will come back to burn because the material does not support the level of heating . However , I don't know if the motherboard was damaged.

By the way, in case of damage, which motherbord should I buy?

thanks,

Nelson

SD3 Sanguinololu motherboard

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4 Reply by wardjr

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Re: Print bed doesn't heat

Well there's the problem... You don't have the bed heater plugged in wink
Just messing with ya, looks like you did a nice clean job so it is tough to say what is wrong.  All you can do is look over the traces on the board and try to identify the issue.  Take the board out and get good pictures, maybe someone can identify a problem area.
As far as replacement boards go there are many to choose from, it really depends on your future needs.  I really like the Rumba for its robust nature and future expandability.  It has pins and terminal screws for most connections and superior fan control.  Not to mention a separate isolated circuit for the bed heater.  But, it is expensive so if you have no intentions to utilize any of those features than look for a cheaper alternative.

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

wardjr's Website

5 Reply by jagowilson (edited by jagowilson 2015-03-30 18:29:40)

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Re: Print bed doesn't heat

Since you have a Sang you can get a Rumba for $80 from RepRapDiscount since you already have atepper chips you can use. Not saying you should replace the board, but if you don't need drivers the rumba is sub-$100. Typically this area of the board fails ALWAYS-ON (burned up mosfet) so id be surprised if the board ends up being the culprit. You can test the board pretty easily with a multimeter. Same for the bed heater. What resistance do you read off the bed?

6 Reply by Whiteshark

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Re: Print bed doesn't heat

Does anybody see where is the problem?

Print bed connector: 2.7 Ω

Motherboard: I don´t know how to test...I need a little help from my friends...

Thanks,

Nelson

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7 Reply by jagowilson (edited by jagowilson 2015-03-30 19:37:01)

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Re: Print bed doesn't heat

In the right of the first picture, I can see where the solder appears to have melted. That's likely your culprit. You can test the board by (carefully) placing the probes on those two solder joints and then requesting heated bed power. I'm not sure I'd bother, because that is definitely toast at that connector. Probably fixable, but I don't know what's involved (not sure if you can use a soldering iron or if a reflow oven is required).

Your heated bed resistance seems fine.

8 Reply by Whiteshark

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Re: Print bed doesn't heat

jagowilson,

I soldered again the print bed mosfet and tested the board:

print bed: 0 V
and i tested too the extruder: -12,26 V

as I had to turn on the machine , the test with the multimeter was in volts . correct?

Please let me know what it means with this print bed value.

thanks.

Solidoodle 3, Slic3r, ABS

9 Reply by jagowilson

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Re: Print bed doesn't heat

Well if the bed reads 0v and you had the bed turned on, no current is flowing. I'm not sure what you need to replace that FET, but the numbers on it should point you in the right direction, if it is the actual culprit.