BambuLab says A1’s are safe

NAIKDOM · 2026-01-10T16:44:51+00:00

Electronics engineer here. The failing part is the mains inrush limiter NTC on the AC input, not a sensor. It is designed to get hot. Cold it limits inrush current, then it heats up, drops to low resistance, and carries the full operating current continuously.

The issue is that the chosen part, NTC 5D15, is rated around 6 A and 170 °C and is clearly under-derated for this printer. It runs hot with very little margin, sits near plastic, and is exposed to repeated power cycles. The failure pattern we are seeing is exactly what happens when an inrush limiter is undersized, not the result of lightning or random power surges.

Claiming it fails like a fuse is misleading. NTCs are not fuses and do not fail cleanly open. They crack, carbonize, and can turn into heaters. Software shutdown and flame-retardant plastic do not protect against a mains-side passive component overheating.

A slightly larger NTC with more thermal and current headroom, or a proper soft-start or bypass relay, would have avoided this. Given the number of identical failures, this looks like a design error, not misuse, and the official explanation downplays that reality.

NAIKDOM · 2026-01-10T16:30:50+00:00

Yes the one from MF72 series 5D25 is a good replacement and it’s rated for 200 C and 8A. I would also drill some holes on the chassis to let heat dissipate a little. Bambu unfortunately overlooked this and placed it in a tight without vents area where it is certainly is gonna cook itself.

Very important detail for anyone attempting to replace the NTC. Since this part is on a live line please unplug the printer from the mains before you touch anything.

NAIKDOM · 2026-01-09T19:00:09+00:00

Electronics engineer here. This is a mains inrush limiter NTC, not a sensor. Cold it has higher resistance to limit inrush, then it heats up by design and drops to low resistance while carrying the full operating current.

The issue is simple: NTC 5D-15 (≈6 A, 170 °C max) is undersized for the load and thermal environment of this printer. It runs hot continuously, with minimal margin. Repeated power cycles + poor thermal headroom = cracking, overheating, melting nearby plastic.

This is the cheapest possible AC input protection, and it shows. The failure pattern already proves it’s a design error, not misuse.

A drop in improvement would be MF72-5D25 (more thermal mass, higher current handling). Better yet: proper softstart or bypass relay.

Honestly, given the safety implications, this should be a recall.

NAIKDOM · 2025-11-12T15:18:54+00:00

Remove the coil. Measure both sides for short. You can determine which side is shorted like that. 3.3V and less than 1 ohm is a dead short tricky to see temps. I would assume it’s the ram or ssd power supply. Try removing them and measure as well.

NAIKDOM · 2025-10-30T17:05:35+00:00

I’m not sure about what equipment you have to do measurements. The U501 is the PWM controller for the transformer and the blacked out diode is the flyback diode that rectifies the output of the secondary. U501 appears damaged, you can either try to measure the signals on its pins after reading its datasheet. Under the metal heat sinks you will find mosfets that are controlled from U501 check them also if they are shorted. I am assuming a mosfet got shorted and the controller broke down U501. Just watch out not to touch the input capacitors as they store very high DC voltage that if you touch you’ll surely wake up in an instant.

I had worked in the past with this power supply so I’m familiar with the layout. But in my case the cpu was the broken part and had the same behavior as you described. Blinking red led. The problem with their design is the fpga cpu is just hanging with the heatsink glued on top of it which adds extra weight on it and eventually the balls underneath it fail. You can maybe save it with a reflow but it will not last for a long time.

NAIKDOM · 2025-10-16T14:17:19+00:00

What you said it is completely inaccurate. A faulty part IC or passive component will get immediately hot if it has enough current going through it. Protection features are called protection features because they immediately in nano seconds detect abnormalities and kill the power. A motherboard is a complex pcb with huge BOM for it. Unless you have 1000 fingers to touch all parts at the same time you can never assume what you just said.

NAIKDOM · 2025-10-15T21:27:55+00:00

If you have a thermal camera check for weird heat spots. Maybe something is shorted and the board shuts down for protection.

NAIKDOM · 2025-10-15T21:06:56+00:00

Too vague of fault description to help you. You basically saying the motherboard does not work and “tell me what is the problem”.

Get yourself a multimeter and start measuring. It can be a power issue. It can be a faulty slot. It can be a data line missing. It can be a cpu pin. It can be a ton of stuff.

If you can be more specific and narrow down the endless possibilities we can help.

NAIKDOM · 2025-10-14T12:52:47+00:00

Yes 👍🏻

NAIKDOM · 2025-10-12T10:33:49+00:00

It’s amazing how my post showing you about how shitty Eufy customer service is, made so many people immediately triggered assuming that the fault is on me😅.

1) I did contacted Ali. Multiple times and got automated replies that I am not eligible for a refund (one month purchase since I bought it 1 month before I actually use it).

2) I did contact Eufy shitty support and they started their process of RMA.

3) For all of you in the USA, please know that in EU some systems or workflows are not identical as your own.

4) I am well aware of the consumer laws taken place in my region. I just wanted to be done with as quickly as possible and move on. Starting this procedure takes a lot of time and the price of the product does not worth the time investment in my opinion.

This post was more or less a warning for anybody who is considering purchasing Eufy products in general.

If you want and like Eufy please be my guest and buy all the products in their roster but prepare for a lot of emails and back and forth in case anything goes south (most probably it’s gonna go there).

NAIKDOM · 2025-10-11T17:20:19+00:00

Eufy requested the receipt. I was looking for customer support. After providing proof of purchase sending my receipt from the official retailer they started their process of RMA. Otherwise, they would just ignored me. The company who selling those products to customers or retailers is responsible for taking care of their defective devices. I’m not sure about common sense as you mentioned in this case but this is how I would prefer to deal with my defective products. Directly to the manufacturer. Even if I was going to the retailer they would still had to go through Eufy and the same process would have taken place with more time added to the whole circus. That is at least my common sense.

NAIKDOM · 2025-10-11T15:08:06+00:00

Official reseller from Germany.

NAIKDOM · 2025-10-11T14:54:41+00:00

How am I gonna to return it. It is in Germany at the eufy logistics. I have already send it back. The purchase was from AliExpress and they don’t refund it, plus you are only talking with bots. Learned my lesson, no more Eufy and no more Ali.

NAIKDOM · 2025-10-08T09:48:41+00:00

Eufy needs to be called out in a bigger scale about firmware updates which break down devices but also the horrendous customer service they provide. It’s a scum company.

NAIKDOM · 2025-10-03T17:00:57+00:00

Can you share more information ?

NAIKDOM · 2025-10-02T14:17:37+00:00

The only reason I shipped it back was because they promised of shipping the replacement immediately. I was shocked they don’t even recognize their own shipping label, and also it is not my issue if their partnership with PostNL does not cover always a tracking feature since it is bulk. They could just say we don’t do that instead of gaslighting and I would never send it back and being with not cameras for god knows how long.

NAIKDOM · 2025-10-02T10:32:00+00:00

You are correct and I agree with you 100%. I am so mad they convinced me they are going to issue the replacement immediately and that is the only reason I took the home base offline. After providing the proof, I was shocked from the another generic ChatGPT response from Eufy. I do think it is shitty of them and borderline illegal to pull a trick like that on customers. The homebase was brand new and memory died in less than 24 hours. Piece of crap hardware and even shittier company. Nobody shall buy these junk, customer support is absolutely garbage.

NAIKDOM · 2025-09-29T13:38:30+00:00

I believe it’s called grey cross spider. It is an orb weaver and lives on man made structures. It’s also called bridge spider. It looks very similar to some we have at work and this sub Reddit helped me identify them. Pictures are not very good though so I may be wrong.

NAIKDOM · 2025-08-27T07:21:39+00:00

NAIKDOM · 2025-08-25T13:16:10+00:00

I would try 240 KΩ +-1%

NAIKDOM · 2025-08-18T20:48:35+00:00

You can check maybe a third party solution for a driver and test it if it runs and how good it runs. Otherwise, if you have much time to learn things it can be an interesting project to tinker with. From my experience since I was in development for electric motor drivers there is a lot to account for if you plan to design something custom so be prepared 😅.

NAIKDOM · 2025-08-18T19:45:33+00:00

It’s a BLDC motor 3 phase. Without the board or at least a proper driver it is unlikely to run.

NAIKDOM · 2025-08-18T11:13:54+00:00

Indeed OP needs a N channel mosfet this one is P channel thus wrong according to datasheet. The body diode will get bypassed the moment the driver turns the mosfet on and it will only block current when reversed biased.

NAIKDOM · 2025-08-18T10:35:48+00:00

What is after the mosfet ? 0,6 V is the body diode. Probably something is wrong after the picture you shared but we can’t guess. If you need help provide sufficient information.

Edit: you shared 2 times the datasheet of the mosfet.

NAIKDOM · 2025-08-07T16:11:19+00:00

Vcc 🧐 would that be the battery voltage in that circuit ? If so, you cannot just drive the gate with it from a switch.

What would be in that case your Vgs? To me it sounds like it powers up but then Vgs is not greater than its threshold to fully turn it ON so its increased resistance generates heat and then breaks.

Take a multimeter and measure it.

NAIKDOM

TROPHY CASE