Bed heater wont go past 50C

Hmm, well the bed doesn't actually get hot, so I am guessing the thermistors are reading the actual temperature, and that either the bed heater is not providing enough resistance, the power supply bad and needs to be more like 13.8 volts, the motherboard power transistor is being PWM modulated improperly, or some other problem.  I have oscilloscopes and other test gear, but am looking for the "Oh I know what is causing that problem - experienced person at Solidoodle who has seen it all" to save time and diagnostic work.  Also I can measure the bed temp with a digital thermometer, and so far could easily touch it without getting burned, so it is not getting hot enough.

I get a error message saying resetting use M999 or something like that.

My laptop is just sitting there never, sleeps.  USB connection is never lost apparently.

I'll check the thermistor connection, but it seems to be indicating the actual temperature correctly and starts at around 20c then climbs to 48c or so but will not keep climbing hotter, then with the having SLOWLY reached 120F (48C) the system turns off bed and extruder heat and faults (in manual mode in repetier).  It would be helpful to know what the normal bed heater element resistance is supposed to be, as I think that is the culprit.  I may just attach the heater bed to my 13.8 volt 10amp DC power supply for ham radio mobile units and see if it will ever get more than 50C running directly off the power supply without the controller board and measure the bed temp with a separate digital thermometer.

Also, I see you both have replaced a lot of parts in your Solidoodle machines, and both have alternative beds.  If this is so, why?  Is the Solidoodle machine as supplied somehow inadequate, or worse broken to actually just work without a LOT of screwing around and replacing half the guts.  If that is so, then this is a problematic situation that sets up customers for frustration and failure.  In cars this is called a Lemon and subject to recall, ARG...

Also I am planning to make an enclosure, boy would be nice if Solidoodle made one, oh that is called a Soldoodle 4...  Solidoodle 2 can get an upgrade case.  Anyway, clearly the machine is meant to run in an enclosure to keep the print temperature hot and this goes beyond what the bed temp issues are.  Is a lexan top, sides and door that is pretty air tight adequate or do I need to actually use something with some insulation coefficient?  thanks for the advice.

Oh - and for what its worth, I've done 500 prints on the stock bed (with glass + hairspray). It does work fine, assuming there isn't some wiring issue.

Not sure if this was covered, but the resistors can get a partial burn-out. I don't know how it works, internally. To my understanding, these are nichrome wire set in some form of ceramic, cased in aluminum. But frankly, what I do know, is that I took apart my printer with a similar situation and found what's nominally something like 3-4 ohms was 7.9 ohms, and I wasn't reaching past 65C. A higher resistance means it will pull less from the system, so you would not be able to go too high in temp.

I should note, my heater didn't fail until after about 13 months of running it near 90C.

Eventually I replaced the whole shebam with 2.4 ohms of nichrome wire. I applied two layers of thin kapton, added my wire in a zipzag form, then two layers of kapton, then a layer of aluminum (to reflect), then more kapton, then the standard insulation.

Regards

^With respect to what Ronsii said:

I personally have an older SD2, so mine was just an aluminum resistor. Yours can be a pad. I dont know how common the problem would be with the pad. But all you have to do is measure the resistance of it. This can be done without taking apart the bed.

I just reread the first post   @Simmunity, are you turning both hotend and bed on at the same time before printing? if so then you may be risking a clog from the hotend being on too long without extruding and also the 999 error is probably from the PID's not being tuned properly... maybe it would help to see a pic of the temp graph in RH if possible.

And the circle is complete

Why are you apologizing?  You had a valid thought.

The circle is complete because we are back to the first response from me that suggested a bad connection or short with the thermistor.

Probably a silly question ,but can the bed be powered by external sourse? If so how would you regulate the temperature?

You can easily take the current bed output and feed it into a relay/SSR then pipe independent power into the relay to be switched to the bed, this leaves the stock pid controller in charge of maintaining temperature while using a separate power supply.