DOA boards

Are DOA boards just par for the course?

3x maple mini clones arrived from China today, 2 are good, 1 is dead – the voltage regulator got very hot right after plugging in to USB, on closer inspection one side of the ST chip has ~ 6 pins mis-soldered together.

I don’t have the tools to attempt a fix, my soldering iron is not fine pitched enough for delicate SMD work and I suspect that the fault is probably terminal anyhow.

So is this pretty common?

Not had that issue, no. I have seen some pretty sub standard soldering though, but so far all of the boards I have bought have worked. Well until I broke them of course… Furthermore despite several attempts, I have jet to actually kill one, and not be able to fix it, so they are pretty robust.

You could complain to the supplier, most times I have done that, for other problems, they have sent out a replacement without any quibbles. One even sent me a replacement order when I simply suggested they use antistatic protection in the future. The replacement chips were also stuffed in polystyrene foam and no anti-static protection. I didn’t think it was worth complaining about the replacements. Both batches worked.

BTW put a dollop of flux on those mis-soldered pins, and some fresh (leaded) solder and drag solder the blob to the edge and off. So long as the pins are aligned with the pads, this will clear up that kind of sloppy solder 99% of the time. No specialist tools required, just flux, solder a fine tip and a steady hand. It might take a couple of attempts, but you have nothing to loose.

Of course the fact that you didn’t spot the issue till after you roasted the regulator means it might not work, even after tidying up.
If its still dead…. aim straight … fling —–> bin. At a couple of bucks a throw, it should make a satisfying clatter as it hits the bottom.

Don’t wast too much time over it, and use a different supplier next time, if they don’t offer a replacement.

I’ll see if it can be rescued. Not holding my breath.

Will see what the vendor says too.

Well, no joy there, one of the tracks lifted

BennehBoy wrote:Well, no joy there, one of the tracks lifted

PA4 (14)

VSS_1 (23) & VDD_1 (24) are also a mess, some of the pins don’t even align with the tracks.

toast.

So earlier I said 3 from China, it was actually 2 from China both of which are fine, and this 1 from a UK vendor (impatience got the better of me).

Vendor has agreed to refund half the price, with this being the last one he had, and me having already soldered headers/attempted to fix the problem. TBH I think that’s fair enough, it’s only a few quid.

Hmm

The board that I’ve been using now refuses to show up in device manager, it appears as a maple dfu, then ejects itself but does not add the serial usb device… suspect flashing failed….

Do I need to debrick it with st-link? (which I don’t have lol)

NM managed to rescue it by catching it when in DFU mode.

BennehBoy wrote:NM managed to rescue it by catching it when in DFU mode.

BluePill boards are not well designed or manufactured

In addition to the poor build quality, they have a shoddy usb connector and wrong value of USB pullup resistor.

I have some GD32 boards which have the same problems (dodgy USB connector)

Unfortunately, you get what you pay for.

The Maple mini clones, especially the ones direct from the manufacturer (“Baite” store on Aliexpress) are the best bet, but are twice the price of the Blue Pill

The Black Pill is also OK, and a bit cheaper than the Maple Mini

Plenty of other larger boards are also OK (but more expensive)

The “Ugly board” is another to avoid, but fortunately people seem to avoid it (or perhaps its not so widely available as it was)

ahull wrote:
Get yourself an St-Link V2 clone, you can de-brick anything which still contains its magic smoke.

RogerClark wrote:BluePill boards are not well designed or manufactured

In addition to the poor build quality, they have a shoddy usb connector and wrong value of USB pullup resistor.

Well it’s a good job I ordered an st-link, just killed this fist board by attempting to put the v2 bootloader on it, sigh – I can never leave good enough alone

killed != bricked

but then again, not always

BennehBoy wrote:RogerClark wrote:BluePill boards are not well designed or manufactured

In addition to the poor build quality, they have a shoddy usb connector and wrong value of USB pullup resistor.

I was very lucky, I got only a nodeMCU with broken reset button and a nasty STLink clone that works with STM32 but not with STM8. I suspected that something was wrong with wires until I got another STLink (Baite) that works with STM8.
Some of UNO clones has regulator that doesn’t allow the same 5V current as the original one.

But original UNO has a nasty bug on serial due to the 16u2 MCU. When you open the serial port without resetting, the 16u2 send a pulse of about 4 us to the RX port of the Atmega328. This pulse can be interpreted as a characher that depends on baudrate

A 256000 you get a zero
At 128000 you get F0
At 115200 you get F0
At 38400 you get FF
At 9600 you don’t get any strange character because the pulse it’s too short.

If you install the HoodLoader2 bootloader in the 16u2 MCU, you don’t get this issue

If you use a clone with CH340 chip, you don’t get this issue.