Onyx Heat Bed runs cold

[MWProtoType]

Yesterday I was printing a rather large part out of ABS and it finished fine. however, after attempting to start a new part later that night the Onyx Heat Bed will not heat any longer. I have checked the fuse and it is good. wires all seem to be connected properly. all other functions work fine on the machine. No idea where to go next.
Thanks,
Mike

[Jimustanguitar]

Does the LED on the Onyx light up?

Does it show a temperature on the LCD?

Also check for error messages when you connect in Repetier.

[MWProtoType]

it does not show a temp on the LCD.

Unfortunately my LED on the board has never lit up but it has worked flawlessly until now.

no errors on connection.
11:11:11.628 : FIRMWARE_NAME:RepetierMAX 0.83SeeMe FIRMWARE_URL:https://github.com/seemecnc/RepetierMAX PROTOCOL_VERSION:1.0 MACHINE_TYPE:RostockMAX EXTRUDER_COUNT:1 REPETIER_PROTOCOL:2
11:11:11.628 : Printed filament:3313.48 m
11:11:11.628 : Printing time:21 days 5 hours 36 min

[Tinyhead]

Do you have a multimeter to verify that 12V is being sent to the bed output on the Rambo?

[Eaglezsoar]

There is an LED under where it says heated bed, does the LED come on when you tell the heated bed to warm up?
If the LED does come on you need to check with a voltmeter if the 12v is getting to the heated bed. First carefully
measure the heated bed connection on the Rambo for 12V be careful not to short anything. If 12V is present there
then measure for 12V at the connections to the heated bed. If 12V appear at the connection to the heated bed then
you have a heated bed problem (bad Onyx) which is extremely rare. Come back with a message of what you discover.
There are 3 fuses on the Rambo, one large fuse and two small ones that fit into small sockets on the board. With the
power off gently lift the small fuses from their sockets and measure them to make sure they are not open.

[MWProtoType]

ok looks like i found the problem. one of the contacts overheated somehow and melted the connection to the board. not sure how I missed that before. the rest of the board continues to work just fine but printing abs is not an option at this time. I guess I am going to need a new board unless there is a way to use a different set of pins for the Onyx board.

[Eaglezsoar]

ok looks like i found the problem. one of the contacts overheated somehow and melted the connection to the board. not sure how I missed that before. the rest of the board continues to work just fine but printing abs is not an option at this time. I guess I am going to need a new board unless there is a way to use a different set of pins for the Onyx board.

That has happened to many users, the connection is not tight, forms a high resistance and begins to get hot and melts the connector. Ultimachine offers a board repair service for
a nominal fee if you contact them. I do not know of any other connectors that you can hook the hotend to. You may have to buy the new board and send the old one in for repair.

Here is what happened to other users:

Melted Rambo.jpg (42.82 KiB) Viewed 12496 times

[MWProtoType]

yep that is what it looks like.

[lightninjay]

Sorry to ressurect an old thread, but I'm now having the same issue. The only difference is my connector on my board is just fine. The printer comes on, the hotend comes to temp, everything functions except the heated bed temp, and the heated bed LED.

I haven't checked to see if the RAMBo lights up the heated bed LED on the board itself yet, currently my printer is slightly disassembled so I could track down this issue. I do think I have a possible short in my Onyx Rev 5.

Tell me if I'm doing it wrong, but when I check the resistance of the heated bed coil, I get 1.4 ohms. I have the bed completely disconnected from the RAMBo currently.

[Eaglezsoar]

The 1.4 Ohm resistance is what I would expect to see as the resistance of the Onyx Rev 5 Board.
My guess is that the heated bed led is not lighting on the Rambo board when the heated bed is supposed to be on.
If the led does not light at the Rambo board, check the automotive style fuse and make sure it is not blown.
Other problems may be wires that are not making secure connections or the Rambo board itself is in need of repair.
If still in warranty a defective board can be sent to Seemecnc after contacting them at [email protected]

If the board is no longer in warranty, Ultamachine can repair the board for a nominal fee.
Ultimachine can be contacted here:

1-423-228-0005

[email protected]

UltiMachine
200 12th St. N.
South Pittsburg, TN 37380 USA

[lightninjay]

So get this Eagle, the RAMBo lights up the Heat2-Bed led, and provides 11.5v current to the output of "Heat2-Bed" on the RAMBo. The moment I secure the 12v wires that go to the large solder pads for the heating element to the Heat2-Bed inputs, the LED won't turn on. It is noticeable however, that when the heated bed is triggered within Repetier-Host to be turned on, the RAMBo does flash the LED to Heat2-Bed very quickly before turning off again.

Would this then indicate a fault somewhere in my heated bed?

The thing is, my printer has been running fine. It was warming up for a print, then all of a sudden, the heated bed LED turned off, and the temperature for the bed on the LCD started to coast downward.

Attached are photos of my board powered up with LED's on when there is no connection to the heated bed, and off when there is connection.

EDIT: I also just tested the voltage on the RAMBo, both connected and unconnected. Unconnected, the Heat2-Bed connector puts out 11.5v. With the heated bed screwed in and power supplied, it shows 30v?! What is going on here?

Both hotend and bed turned on yields all the lights, when the bed isn't plugged into the board.

Closeup to show that "Heat2-Bed" has nothing connected.

This is when the bed is connected, and Repetier has signaled the bed to turn on. No light :(

[Eaglezsoar]

We must stop for a moment and diagnose how the heated bed output can go to 30V.
Do you have any other power supplies attached to the Rambo? What voltage to you have connected to the Heat Bed Input on the Rambo?
When you are measuring the voltage outputs and received the 30VDC measurement are you sure that your meter is set to measure Voltage DC and not Voltage AC?
Just trying to be thorough because what you have observed is is not logical in a 12VDC only environment. Please get back to me.

[lightninjay]

Hey Eagle, further testing proves even further inconclusive results. I'm certain I'm using the meter properly, but now I've gotten a different set of measurements than before!

Unstressed, or without the hotbed plugged in, the outputs are reading 9.5V. However, with the bed plugged in and on, it pulls 24V!

EDIT: I'll try to take photos, as I sound like a loon explaining it this way.

I have the Viotek supply shipped from SeeMeCNC and no extra supplies added. I suppose it could be drawing extra voltage from my laptop through USB, but that's somewhat unlikely I would think.

I used GeneB's instructions as per the manual and combined a few of the 12v rail wires in a bundle for the heat bed input, and duct taped them right at their neck to keep them tidy, you can sorta see this in the right-hand side of the very last photo I posted.

EDIT: Here are some photos to illustrate my methods. It seems like the voltage is slowly coming down. Could this be my RAMBo slowly suffering a cataclysmic failure on the Heat2-Bed output circuit? Everything else on the RAMBo seems to function perfectly except this single circuit. I've been eyeballing the RAMBo 1.3L schematics for the past hour seeing if I can pick out something that would do this.

Measuring VDC

24.3V

Slowly going down.

[Eaglezsoar]

Hey Eagle, further testing proves even further inconclusive results. I'm certain I'm using the meter properly, but now I've gotten a different set of measurements than before!

Unstressed, or without the hotbed plugged in, the outputs are reading 9.5V. However, with the bed plugged in and on, it pulls 24V!

EDIT: I'll try to take photos, as I sound like a loon explaining it this way.

I have the Viotek supply shipped from SeeMeCNC and no extra supplies added. I suppose it could be drawing extra voltage from my laptop through USB, but that's somewhat unlikely I would think.

I used GeneB's instructions as per the manual and combined a few of the 12v rail wires in a bundle for the heat bed input, and duct taped them right at their neck to keep them tidy, you can sorta see this in the right-hand side of the very last photo I posted.

Read the voltage input at the Rambo's heating bed input, directly from the power supply once with the heating bed off and once with it on.
Read the voltage output at the Rambo's heating bed output directly at output screws once with the heating bed off and once with it on.
Also, in the last photo it seems to look like the mv is indicated, is that correct?

[lightninjay]

All four readings in the order I took them

Heated bed connected and powered on in Repetier-Host, output from RAMBo (green sockets) : 23v
Heated bed connected and powered on in Repetier-Host, input from power supply (big black connector) : 23v

Heated bed disconnected and powered on in Repetier-Host, output from RAMBo (green sockets) : 8.5v
Heated bed disconnected and powered on in Repetier-Host, input from power supply (big black connector) : 8.5v

[Eaglezsoar]

All four readings in the order I took them

Heated bed connected and powered on in Repetier-Host, output from RAMBo (green sockets) : 23v
Heated bed connected and powered on in Repetier-Host, input from power supply (big black connector) : 23v

Heated bed disconnected and powered on in Repetier-Host, output from RAMBo (green sockets) : 8.5v
Heated bed disconnected and powered on in Repetier-Host, input from power supply (big black connector) : 8.5v

Turn off all power and remove the 12V wires from the Rambo Heat Bed power in and swap them for a different pair of 12V wires. I have a suspicion what is going on but won't know for sure until
you swap out the wires. After making the swap, turn the printer back on and measure the input from power supply (big black connector) for the Heat Bed. It was reading 23V I need to know if
it is now 12V with the bed turned off.

[lightninjay]

Just to confirm, are you asking me to connect a different set of YELLOW and BLACK 12v source wires from the power supply to the black connector block which connects to the RAMBo? Or are you just asking me to put a different 12v device in the place of the heated bed?

[Eaglezsoar]

Just to confirm, are you asking me to connect a different set of YELLOW and BLACK 12v source wires from the power supply to the black connector block which connects to the RAMBo? Or are you just asking me to put a different 12v device in the place of the heated bed?

I am asking you to connect a different set of YELLOW and BLACK 12v source wires from the power supply to the black connector block which connects to the RAMBo Heat Bed INPUT.

[lightninjay]

Yup, that's what I thought you were asking. I don't have any other 12v source wires from the power supply

[Eaglezsoar]

Yup, that's what I thought you were asking. I don't have any other 12v source wires from the power supply

Just swap any of the yellow and black wires on the black connector with the yellow and black going to the Heat Bed Input.

[lightninjay]

So here's what I've got before I swap anything. This is per Gene's instructions from the manual (twist the four long black wires and the four long yellow wires pg. 29 manual vs. 1.67)

[lightninjay]

Eagle, by any chance would your theory be that I have a bad power supply? Because the moment I switched the heated bed lines (which were only putting out around 8v) to the logic lines (which were doing fine around 11.5v before being switched) and I turned my printer on, the screen was very dim and the rest of the board seemed to be getting less power.

EDIT 1: I can confirm that after the switch, the logic lines are only able to pull 4.5v from the power supply through ONE of the yellow and black pairs from the original braided FOUR for the heated bed. Does this mean that Gene's suggestion of combining rails is a bad one? Or am I way off course here? Because I also measured the rail that I switched from logic over to the bed, but I couldn't put it under load through the board because the logic lines are low. I'll try putting the low lines on the motors since they are of little consequence currently.

EDIT 2: Confirmed the printer can boot up and that switching the low lines to the motors doesn't bring the rails up and in fact draws the rail all the way down to 2v. I suspect a bad power supply in this case. Anyone disagree? I just wonder what would have killed the rails. Perhaps many prolonged prints at high bed temps (90C)? I sure hope it isn't an issue in the Heat2-Bed input area of the RAMBo. The schematic for that area from the power source over to the output for the bed to connect to is a relatively short path and it doesn't appear as if any components on the board have fried.

[Eaglezsoar]

Eagle, by any chance would your theory be that I have a bad power supply? Because the moment I switched the heated bed lines (which were only putting out around 8v) to the logic lines (which were doing fine around 11.5v before being switched) and I turned my printer on, the screen was very dim and the rest of the board seemed to be getting less power.

EDIT 1: I can confirm that after the switch, the logic lines are only able to pull 4.5v from the power supply through ONE of the yellow and black pairs from the original braided FOUR for the heated bed. Does this mean that Gene's suggestion of combining rails is a bad one? Or am I way off course here? Because I also measured the rail that I switched from logic over to the bed, but I couldn't put it under load through the board because the logic lines are low. I'll try putting the low lines on the motors since they are of little consequence currently.

EDIT 2: Confirmed the printer can boot up and that switching the low lines to the motors doesn't bring the rails up and in fact draws the rail all the way down to 2v. I suspect a bad power supply in this case. Anyone disagree? I just wonder what would have killed the rails. Perhaps many prolonged prints at high bed temps (90C)? I sure hope it isn't an issue in the Heat2-Bed input area of the RAMBo. The schematic for that area from the power source over to the output for the bed to connect to is a relatively short path and it doesn't appear as if any components on the board have fried.

The bad power supply is exactly my thoughts. You are getting low current 23V from one of your yellow wires which should not be possible from a 12V power supply. That is why I wanted to swap out the pairs of wires going to the Heated bed input. You have discovered lines that are low current outputs when they should not be. My first suggestion at this point would be a new power supply. Keep me updated.

[lightninjay]

So Carl, you probably won't believe this, but by sheer chance, of all the yellow 12v wires I could've picked to wind together, I picked 4 that were all on the same rail. Yes, apparently this power supply (Viotek 550w) has two separate 12v rails, even though it is only advertised as one single rail. Attaching photos below.

As you can see, there are two areas, labeled +12v1 and +12v2.

On the back, there are even two separate trace pads for different clusters of the 12v rails.

In my wanting to keep things clean, most of the other yellow 12v wires were cut, so I suppose the one rail trying to drive the heated bed was just too much for the poor thing.

I scooted up to Best Buy before they closed and bought a Corsair CX750M (750 watt supply if you couldn't tell from the fancy name)

Right now I'm debating on making a conversion cable for the 12v rail so I can easily plug it into my printer and not void the supply's warranty

[Eaglezsoar]

So is W.I.S.P.E.R. W.I.S.P.E.R.I.N.G again?