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Topic: Bed Heat Fix

OK, so this weekend my bed refused to heat.
I found and fixed it, Here's how:
Flipped it up and opened the circuit board compartment, power on, Bed Heat on.
Measured the Control Board (PCB) output to B-Heat, got 24VDC.
Power OFF, reinstall PCB and close up compartment. Set unit upright.
Power on, Move Bed Down 100mm from near extruder (about half way down, however far you need to move it). Power OFF.
I opened the unit door, removed the glass, then Removed the 4 screws securing the bed.
Slide the bed forward until you can flip it over. Examine the wires, Mine had charred insulation on the far right wire.
Got out the razor knife and opened the bubble on the heat pad where the wire enters.
Found many broken strands of wire, Powered up and verified I had 24 volts to there but I could see some strands of the heat bed glowing red hot. POWER OFF
Grabbed the Weller Soldering station and powered it up.
Scraped and blew all the charred stuff away from the wiring.
Using various probes and such I gathered all the strands of wire on the Bed heater and soldered them to the wire from the PCB.
Leave the bed flipped over to test.
Power ON, Bed heat On, bed is heating, no glowing wires. POWER OFF.
Found my tube of unopened RTV had gelled in the tube. GRAHhhhh!!!!!!
Off to Home Schlepppo for RTV or such.
Got a bottle of liquid tape, some zip ties and other stuff as I was there.
Back at the printer, sealed the joint with liquid tape.
Wait for it to set up. While waiting use zip ties on the back of the carriage to make a place to secure the wires so they won't wobble and break again. I used 3, 2 left loose for now, add third later. One around each side of the middle notch to the holes on each side for the glass plate stops. Later, one in the middle to put around the wires.
Wait for the insulation to set up, takes 5 min but might need a second coat, mine did.
Then re-install the bed.
Now move the bed up, then add the third Zip tie around the wires and between the 2 others, Snug it up. Then tighten the other 2.
It should now heat right up. And the wires won't break again from being bent back and forth at the heater input.

Scramjet

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Re: Bed Heat Fix

OK, So I got one more day out of the Bed Heather, then I could see it was heating the connection to the bed again.
Tore it back down, Seems the wire in the Bed does NOT take solder, thus why it was crimped on before.
So, I ordered the only 24V bed heater on Amazon and have to wait over a week for delivery.
The new bed is also a metal bed with internal heater, takes 12 or 24 V input.
Price was not bad tho. Lets see how well it fits now.
Supposed to be a 214mm square bed w mount holes for a RepRap printer, Wish me Luck on holes mating up.

Scramjet

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Re: Bed Heat Fix

If you're stuck a few days waiting for your new heater, and you have some BAG-24 or "safety-silv 50N" brazing solder around, you can try that. Haven't tried it, but heard the nickel in it helps wet nichrome (also needs proper range of flux). Need a torch for that kind of temp, so not sure if it's practical in your case.

4 (edited by ScRamjet 2016-05-07 01:03:20)

Re: Bed Heat Fix

Thanks for the post Raytracing but I just waited for the new Heater, Torch on Rubber didn't seem like a good idea.
I do have some silver solder and a torch for working on water pipes but suspect it would need a good insulating baffle and I don't have one that thin.

New Pad is in and I'm testing the printer now

Take Care !

ScRamjet

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Re: Bed Heat Fix

It's surprising what you can do with a minitorch and heat shield, but I'd have to be pretty bored or desparate to try it because it'd probably eventually break again next to the solder. Glad to hear to you're back in business.