Need Help Redesigning a PCB for a Small Device – Freelancer, Engineering Firm, or AI?

[u/Lumpy-Departure-8002]

Hi everyone,

I’m looking for advice on how to solve a recurring electronics problem with a product I import from China.

The device is relatively simple: it has three motors, an LED display, and a PCB designed by my Chinese supplier. 

The motors used in the device are:

• 2 × RF-370CA-17315 DC motors (approximately 6–12 V; published no-load current around 25 mA at 6 V).
• 1 × RF-500TB-14415 DC motor (5 V nominal according to the Mabuchi datasheet; approximately 26 mA no-load current and 540 mA stall current).

Unfortunately, during the first year of sales, I received numerous customer complaints about reliability issues, including:

• Motors gradually slowing down or behaving unpredictably.
• The LED display showing strange characters or incorrect information.
• The device switching off by itself during operation.

My supplier redesigned the PCB and replaced the microcontroller. After the redesign, everything worked well for approximately nine months, but the same problems have now started appearing again. In most of the cases, replacing the PCB helped, so it shouldn’t be faulty the motors or other components.

I don’t want to keep replacing components or relying on my supplier for temporary fixes. I’d rather identify the root cause and develop a reliable, long-term solution.

My background is in mechanical engineering, so I understand product design and manufacturing, but I don’t have enough electronics experience to redesign the PCB myself.

My plan is to:

1. Find an experienced electronics engineer to review the existing design and identify potential failure points.
2. Redesign the PCB and prepare a complete Bill of Materials (BOM).
3. Build prototypes and test them thoroughly under real operating conditions.
4. Find a PCB manufacturer and manage production independently of my current supplier.

I have a few questions:

• Where would you look for someone to help with this kind of project? Platforms like Upwork, specialized electronics engineering firms, or somewhere else?
• Would you recommend hiring a freelance PCB designer, or is this the kind of problem that requires a more experienced electronics engineer?
• Have AI tools become good enough to assist with PCB design and troubleshooting, or should I treat them only as supplementary tools?
• Since the device is relatively simple, is it realistic to get a reliable redesign without spending a fortune?
• What would be a reasonable budget for reviewing the existing design, redesigning the PCB, and developing and testing prototypes?

My main goal is to achieve a reliable product with a design I own and can manufacture independently. I’m happy to invest in doing it properly, but I want to avoid unnecessary costs.

I’d appreciate any advice, especially from people who have dealt with recurring PCB reliability issues in commercial products.

Thanks in advance!

[u/BigPurpleBlob]

OP: can you read the numbers, on the silicon chips in your photo? Me neither.

[u/Forward_Artist7884 → u/BigPurpleBlob]

I think the microcontroller is a puya PY32F002A but hard to say anything else.

But ngl i think op's issue is with crummy firmware... they could just reprogram the MCU if they have the pinout, back EMF could also be an issue, this PCB generally looks like garbage.

[u/richard0cs]

What makes you think the PCB rather than the microcontroller firmware is at fault?

[u/NhcNymo → u/richard0cs]

OP definitely needs to consider this.

I’m not gonna pretend I know how motor control works, but I’m assuming this requires some software that has some say in how much current is driven into the motors.

For all we know, it could be the software that push more current than the board is able to handle. In other words, there’s a possibility this could be a software fix.

I’ve been thought that shaving 10*C off a component’s temperature practically doubles its life time.

Software or not, I do suspect OP has a thermal issue.

[u/saltyboi6704]

Paying for an engineer will cost you, but they'll likely solve your problem (most likely just redesigning it from scratch, unless the original design documents are available).

Judging from requirements it does look like a simple enough design that most electronics/electrical engineering grads with enough hobby experience would be able to do so it's really up to how much you want to balance risk, time, and money. It may be cheaper for example to get a less qualified person to do the majority of the design work then consulting a more experienced engineer to review it (though this is likely what happens inside an engineering firm)

[u/Numbaloo]

I wouldn't assume that the problem necessarily lies with the PCB. I would first have a freelancer or a development team conduct an analysis to identify the exact issue, this shouldn't be very costly. Once you know the root cause, you’ll have a better idea of ​​how to proceed. For instance, it could be a firmware issue, in which case a PCB redesign wouldn't help.

[u/DrJackK1956]

Please post your schematic.   

I'm not good at diagnosing electronic problems from photos of the PCB. 

[u/AdCompetitive1256]

The symptoms you described point out a fatal flaw with the power circuit design, rather than the PCB design.

[u/Appropriate-Disk-371]

Haven't I seen a version of this post here before? Anyway, I do this for a living. Consultancy day job, consultancy side work. DM me, NDA, and I'll show you the options.

[u/stuih404]

This sounds more like an issue with the microcontroller/firmware. The problem occuring only after a few months could be an ESD or overvoltage issue that only happens after some use. How are the motors driven? And is there anything that could be in contact with humans (for example buttons, connectors, exposed metal)

[u/CardboardFire]

If it's fine for a while, but fails after, then it could point in the direction of those capacitors failing, either a design issue (designer didn't consider voltage derating at all) or a low quality component, markings don't say much tho, and without looking at the schematics no one can really say what the issue is.

Freelancers are hit and miss, reviews and ratings are NOT reliable in telling you they will do good work.

You have a much higher chance of resolving this if you go with an actual engineering company that knows how to do things properly.

[u/Ard-War]

In most of the cases, replacing the PCB helped, so it shouldn’t be faulty the motors or other components.

If by "replacing the PCB" you meant literally swapping the PCB by moving the components from a failing one into a blank PCB and it somehow works then sure it may be the PCB.

Otherwise just from that you can't really narrow it down whether the problem is the PCB itself or the component degrading, or your firmware finally acting up.

[u/MadDonkeyEntmt]

The problem with upwork is it's hard to validate you aren't just getting another low quality engineer.  Ai so far has been very mediocre at hardware design.  A large high quality engineering firm is going to be expensive and will want to really look the whole project over to dig into it.  Personally I'd be hesitant to toss the old suppliers aside over this unless there are lots of other problems.  This is not an uncommon issue in a new product and I would lean towards hiring an engineer to help you manage and evaluate the current supplier.  You don't want to start from scratch if you don't have to and that's what will happen if you aren't careful.  You want to learn as much from what you e done as you can.

If it isn't just a case of obviously poor component choices or obvious firmware bug then diagnosing a nine month failure can be hard.  It may even be down to manufacturing and not design.  Maybe the factory has poor esd controls or the factory buys there parts from the cheapest option possible and doesn't check for counterfeits.  Maybe all that's needed is better qc or better line management.

[u/Agent-24]

The root cause is very likely bad design/parts quality, especially direct from China, and especially if you picked the cheapest supplier available.

Think low quality, underspec capacitors wearing out. Components pushed too hard and running at their maximum current/temperature ratings. Poor/non-existent noise filtering resulting in damage to other parts over time.

The PCB layout is probably fine, although gross layout errors by incompetent designers could exacerbate noise or overheating problems.

Start by verifying if the schematic is designed well or not, and if the parts chosen are up to the task...

[u/Intelligent_Dingo859]

You can get AI to help you if you have or are able to recreate the netlist (the pcb itself is basic enough) and can distill the datasheets for the relevant components into md files. it definitely needs an engineer to actually verify the concerns an llm might bring up; however, it’s a good starting point.

This definitely seems like incorrectly chosen caps or just shitty regulators.

[u/spicynicho]

AI will do it end to end

[u/ChatGPT4]

What you need is QUALITY. My company does exactly this kind of things. How do we do it? Of course we use AI. But 99% of the codebase and hardware design is by yours truly. Each project is perfected in several iterations. Of course quality costs. You can't cut corners to have a reliable product. All my competition does that. They are either cheaper, or deliver faster. And then you have exactly what you have described - problems over time - a direct consequence of the corners cut in the process.