Thanks a lot piercet.
From you message I assume it’s a bed problem and not a power supply issue, right?
I’ll try to check the bed temperature as you suggested and report back.
Thanks again!
I think your investigation into the power supply fixed the power supply issue. Whether its a permanent fix is a very good question. What you are dealing with now is probably a bed issue, either the heater or the thermistor. Especially if it won’t get to heat in stand alone mode from the LCD.
Is there an easy way to “swap” the bed and nozzle energy (for heating) input? This way I could confirm that the problem is the bed itself.
For example if I could switch cables and I observed that the nozzle does not reach 230C then the problem would be the board/power supply (ie the part which delivers the current used for heating). But if the nozzle gets to 230C and the bed still doesn’t reach 85C then I could confirm 100% sure the problem is the bed. Is that possible without destroying the board?
Not really. The Rambo board is designed for the heated bed to be plugged into the heated bed input. The energy requirements for both devices are quite different. You could potentially swap the thermistors if you did some firmware hacking (can’t remember if the parts themselves are the same for those)
An easier way to potentially confirm if the bed is having a problem would be with a multimeter, measuring the resistance of the bed and the thermistors if you can find the correct values for a Taz 2 bed somewhere with it disconnected. Unless the issue is only present under full load, at which point that becomes somewhat dangerous.
There are 5 heating wires inside the heat bed and they tend to burn out where they connect to the main feed wires on the bottom of the heating pad. You could measure the resistance with it unplugged but it would be a very small change in value from 2 or more being broken. But it makes a big difference in the amount of watts the bed heater supplies. If I remember right or even close the reading is about 1.4 - 1.6 ohms.
There use to be a thermal image someone had taken of the bed on their machine failing and how one of the connections failed/burned out while they took the thermal pictures on the forum.
I just had a similar issue with getting the serial time out exception after letting it sit for a month.
In my case it seems to have been corrosion on the USB connector on the LulzBot Mini side. I unplugged and re-plugged everything, and it became an intermittent issue, then I followed up with 5 or 6 disconnect/reconnects, and it seems to have cleared it up.
Thank you for the suggestions on this thread, it was very helpful.
OK after many years I come back here (I had lost my login data). Just to let you guys know that the problem was actually the fan in the power supply. Every time the fan started, the printer restarted.
In the end I just let the fan directly connected, permanently on. And I can live with that extra little noise.
So yes I guess we can call it a faulty power supply.
Thanks a lot to everyone who posted in this thread.