It doesn’t Rain but it Pours !...

[The Hat]

I was working on the idea that it was the motherboard, because 1) the heating plate was working every now and then, so if the heat plate was burned out then the result would be instant, heat on one minute, but never more, which was not the case.

As for the thermistor, I would have taught if that failed then the heat plate would then overheat, or am I wrong, because changing the thermistor is not that hard a job, in fact I have a several thermistor spares from the extra hot ends that I could use, if push comes to shove.

It’s like this, it could be all 3 are problematic, but I don’t know which one to replace right now, and if I can get it confirmed which one is at fault then I will replace it myself, I am not interested in getting it fixed under warrantee, I just wanted fixed...

Thanks guy for the good suggestions, but keep them coming...

 

[FryingSaucer]

I was working on the idea that it was the motherboard, because 1) the heating plate was working every now and then, so if the heat plate was burned out then the result would be instant, heat on one minute, but never more, which was not the case.

If the heat plate was burned out, wouldn't it never heat up?

As for the thermistor, I would have taught if that failed then the heat plate would then overheat, or am I wrong, because changing the thermistor is not that hard a job, in fact I have a several thermistor spares from the extra hot ends that I could use, if push comes to shove.

You may be right, but I just has a quick look at a thermistor datasheet. If I read it correctly, it appeared to very its resistance based on the temperature sensed, not simply switch on or off. If that's so, it's not clear to me what would be the effect if the thermistor was just not working properly. However, I may be completely wrong here. I've never used a themistor in a circuit myself. If the thermistor is a simple on/off switch, I can understand what you mean.

It’s like this, it could be all 3 are problematic, but I don’t know which one to replace right now, and if I can get it confirmed which one is at fault then I will replace it myself, I am not interested in getting it fixed under warrantee, I just wanted fixed...

Yes, it's difficult to know what to do. But if you can easily replace the thermistor, that might be the quickest way to eliminate one of the possibilities. However I'd be careful to do it so you can replace the original if necessary. Also I'm not sure whether the thermistor for the hot end would be suitable for the heat bed - it's covering a different temperature range.

It's a difficult one to debug. Can you easily get a replacement heat bed with integrated thermistor? This would either fix the problem, or if not point to the motherboard as the culprit.

Good luck

 

[FryingSaucer]

I reckon I spoke to soon, the CR-10 is humming away to its hearts content, but the Feckin Mono Mini is now on the blink, the heat bed has all but stopped working, it used to heat every now and then but it has finally pack in altogether.

Did you get your heat bed working?

Mine is not heating nowIt has no excuse - I've been fairly gentle with it. I've not been working it day and night like you have.

I've not investigated yet.

 

[FryingSaucer]

The end pin on the heat bed power connector is corroded or burnt out as in the attached. I don't know why. Maybe the pin was loose and was sparking as the bed moved back and forwards. My Anet A8 was as cheap as they come, so it's not surprising if the connector is also.

I can get a replacement 6 pin male connector at my local Maplin store, but not the female. I thought I'd be able to get one off an old ATX power supply, but they don't use 6 pin connectors. Hopefully I'll be able to get the female socket from Farnell or somewhere.

 

[The Hat]

The end pin on the heat bed power connector is corroded or burnt out as in the attached.

That a pity but I wouldnt blame it on the price you paid, most of these printers use all the same pieces anyway, try AliExpress they may have spares, and don’t be in a rush to get a fix, take your time and do it properly...

Did you get your heat bed working?

Funny you should ask, because I’ve just heard back from Amazon and they are going to either replace the printer completely or give me a total refund.

I was pondering on my response for a while, but I decide to for a refund, it was very generous of Amazon to offer both, because the return period had well come and gone...
Good on Amazon....

 

[stratman]

I decide to for a refund

Which printer will you buy now?

 

[FryingSaucer]

OK, if anything goes wrong, you're better with Amazon than Gearbest, but it's still very expensive for this model. I use Amazon all the time, but I'm not sure I'd buy a 3D printer from them.

Funny you should ask, because I’ve just heard back from Amazon and they are going to either replace the printer completely or give me a total refund.

I was pondering on my response for a while, but I decide to for a refund, it was very generous of Amazon to offer both, because the return period had well come and gone...
Good on Amazon....

Well, perhaps it is worth paying more with Amazon. That's exactly why I use them so much. Great to know it's worked so well for you - a few months 24/7 use of a printer, then an option to work another one into the ground for free.

On the other hand if you're buying a 3D printer kit like I did, you can fix or upgrade most things yourself very cheaply. The only bit on my printer that might be tricky to replace easily would be the heat bed itself, oh and the acrylic parts if they were to break. I've already upgraded the power supply and power feeds, the hot end, printed several parts to improve stability,upgraded the drive belt mechanisms ... If the motherboard goes at some point, the printer is a Prusa i3 design, and it would be easy enough to get a RAMPS board instead.

Fortunately I'm fairly sure my heat bed is OK, and I only have to replace a connector, which shouldn't be difficult.

 

[Redbrickman]

The end pin on the heat bed power connector is corroded or burnt out as in the attached. I don't know why. Maybe the pin was loose and was sparking as the bed moved back and forwards. My Anet A8 was as cheap as they come, so it's not surprising if the connector is also.

I can get a replacement 6 pin male connector at my local Maplin store, but not the female. I thought I'd be able to get one off an old ATX power supply, but they don't use 6 pin connectors. Hopefully I'll be able to get the female socket from Farnell or somewhere.

Probability is that the fried pin made poor contact with the socket and at the high current level arcing occurred.

 

[FryingSaucer]

Probability is that the fried pin made poor contact with the socket and at the high current level arcing occurred.

Exactly what happened.

The connector is a JST . This is rated at 10A. The heat bed can draw up to 11A, more if the supply voltage is more than the nominal 12V. So this part is already on the limit. But these JST connectors use sprung contacts. If there's any vibration as the heat bed moves, you get arcing as the contact bounces. This burns off a little of the connectors, which reduces the points of contact. Eventually there's no contact left and the bed stops heating up.

I couldn't find any suitable connectors that would take enough current so I just soldered the cable direct to the heat bed. I was then concerned how long the soldered connections would last as the cable is moved back and forwards. I needed something to provide strain relief. As usual I found there were several ready made solutions on thingiverse, and I'm printing one of these now.

I'm really glad I purchased the Anet A8. It was a bargain at the price. It printed well from the outset and there's lots you can do at little cost to improve it. But much of the electrics has been designed on the limit, and there several mods to the electrics that must be done, not just to improve the printer but to make it safer.

I'd be interested to know how the heater cable is connected to the bed on the more expensive printers you guys have got.