I know there was a safety recall. Look at this it could be related to what you are reporting. Redirecting to Google Groups 68
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This information is for the original V1 and even though Wanhao likes to use the term recall, it’s not what you think it means. Wanhao posted the information about the problem on their group and left it up to the end user to determine if there was a problem. Wanhao’s fix for the fire hazard… electrical tape. Straight from their post, “In any case, you have found the crimp broken, Please cover it with insulating tape. If it’s beyond repairing, please 1. take a pic of broken heating tube. 2. provide your order No. and contact our distributor to get one free heating tube.” There you go, a Wanhao recall. It is posted on their group and individual owners were not notified. It’s up to you to find the information, check the printer yourself and then tape it or request a tube. This was also in August of 2015, a year and a half ago. Since then multiple revisions have been made to the printer but it still seems to be a fire hazard due to bad design issues that Wanhao does not want to address.
13 days later
Well finally some good news, after being increasingkly disturbed by wanhao so called customer service who plainly told me that my metlzi board was at risk of overloading on the power and hotbed connectorstold me to change over the conns to screwins as any loosness would ramp the 13A that the board rated to to poss 25A, the conns being rated to 15A, so it was a k ocking bet that the board would overload and a fire ensue. I applealed to wanhao who promptly told me that they would only replace board under its 12 month guarantee period WHEN the board had BURNED. I retorted that I was disgusted that they would risk the lives of me and my family over this issue and I would not be running it. I said I would break down that machine send it back and ask for a full money refund. Nothing. So I wrote to Technology outlet that id boughtit from and asked if I could return it back to wanhao through them thinking it would be cheaper. a day after emailing them I got a reply saying the latest Meltzi board had been shipped to me and I would have it in my hands in 2 days. I did. Thank you very much T O. your customer service is nothing like wanhaos and I’m so glad.
I really don’t know what to say about this. I guess I could say that it’s good that you are getting a replacement board and that whomever (I’m assuming Technology Outlet) is providing that board has at least some integrity. But, the fact that Wanhao knows about the problem and is only willing to replace it after it catches fire tells me all that I need to know. To Wanhao money is much more important that human life or consumer property. They are safe in China and do not have to answer to a civil case in the US or UK. Since they know this, why would they lose $30 US per unit on the unsafe machines they have been selling for the past few years? It’s not like they would have to pay anything for their negligence no matter how people were killed or how much property was destroyed. The re-sellers carry less liability but still know they could be named in a lawsuit so they are more likely to help. Maybe the re-seller is just a good person that wants to make it right, which is even better. Either way it is clear that Wanhao doesn’t care about the consumer. I’m glad you are able to get a new board, let’s hope that they actually fixed the problem. They haven’t so far after several revisions so I’m sorry if I’m a little skeptical. Since you are doing the labor yourself, they could always say that you did something wrong to cause the fire. Just keep that in mind.
Best of luck to you and thanks for the update.
I have the machines dowen at the moment cause I’m moving premises but ill let you know when I startup again probs 2 weeks time. 
BTW I am now making my own cnc carriages for all sorts of headsets. that’s why ive got into the boards.
I have a new I3 Plus I ordered in December. I have to had no issues but there is a simple solution. I am going to put in 15 amp fuses between the heaters and the boards if that is what the connectors are rated for. I would much rather blow a fuse than have a fire. I would also point out that this is a $500 printer. To some degree you get what you pay for so I am not surprised that their might be issues. I will say the print quality of the printer while not being nearly as good as my Makegear M2 has been acceptable.
I don’t take issue with you personally but the price of the printer is really not relevant. If a company were selling a $10 toaster that had a known defect and was catching fire would you say, “You should have bought the $20 toaster, I’m not surprised a $10 toaster catches fire.”?
I don’t think you’ve grasped the original thread here, wh are talking push fit connectors V screw in connectors. and the pips on the connectors themselves that go through the main board. its would be very easy to resolder in a couple of connectors but 1. the pin dia has to be what the board will take and its spaceing. if you look for connectors available they are rated up to 30A but have different siting dimensions. These do not allow you to simply change connectors. yes fuses would be a safty barrier but the problem is still then not being addressed . I am sure you would spend all your time replacing the fuses. this is why some have gone for external mosfets. the problem is the boards pinning holes and their spacing, I have just received the latest meltzi and it seems to have addresses the problem. Bad desesign originally has put lives in jepordy and maybe still is doing. this is more a warning than anything else about what to except from goods shipped from china. they don’t carry the same HSE standards that ours do. and if you realise that then at least you can prepare for it. Steve
2 months later
The possibility of 3D printer catching fire also depends on the version of firmware that is installed ! More recent firmwares are more advanced and have the additional protection measures – like against a thermistor coming off place. For example, below you can find a commit message 43c298a (dated Jun 30 2014) from a Marlin Firmware repository. My cheap Chinese 3D printer (with Atmega 1284P) had a slightly older firmware version installed, so I had to update its’ firmware to enable this “Thermal Runaway Protection”! Always update a firmware of your 3D printer!!!
/*================== Thermal Runaway Protection ==============================
This is a feature to protect your printer from burn up in flames if it has a thermistor coming off place (this happened to a friend of mine recently and motivated me writing this feature).
The issue: If a thermistor come off, it will read a lower temperature than actual. The system will turn the heater on forever, burning up the filament and anything else around.
After the temperature reaches the target for the first time, this feature will start measuring for how long the current temperature stays below the target
minus _HYSTERESIS (set_temperature – THERMAL_RUNAWAY_PROTECTION_HYSTERESIS).
If it stays longer than _PERIOD, it means the thermistor temperature cannot catch up with the target, so something *may be* wrong. Then, to be on the safe side, the system will he halt.
Bear in mind the count down will just start AFTER the first time the thermistor temperature is over the target, so you will have no problem if your extruder heater takes 2 minutes to hit the target on heating.*/
I am glad this issue is finally sorted out, I have had no troubles with the new board, in fact I have not set any PIDS and it seems to be fine straight out of the box so far. So if I get you right the thermistor is now set to check temp after initial warm up and go on doing that to be assured that the temperature is constant over time, if its not it shuts down the machine. I suppose this better than nothing and I’m not surprised with the Chinese mentality, but surley introducing more quality components and a safer physical guarantee, like using more quality heatrods that automatically pop when temp over permitted. they always seem to look at and go with the cheapest fix first. Thanks thought for your info, it has eased my mind more about “lights out production” although still not tried it yet. I do however let vmy hi res renderings run all night with no concerns, . Thanks Ste
Hi Stephen, as you see from my comment below, “automatically pop when temp over permitted” is a firmware thing. Many of Chinese printers are using outdated firmware that is based on old Marlin firmware - which didn’t have these kinds of safety protections at this time. For that reason, I believe that every owner of cheap Chinese printer should manually update their firmware to the latest stable Marlin version, to avoid these possible safety problems, and improve the printing quality in general