Dead bluepill board ? Not so fast

 

That's the second time it happens to me, so i may as well share the tip.

If your board appears "On"  but does not reply to SWD or serial programming, look at the green led. 

If it is  a bit dim, measure the voltage on one of the 3.3 v pins.

If it is weak (like 2.5 v), it might be the 5v->3.3v regulator at the back that is dead.

They are weak and die easily (shortcut, pull too much current...)

So here is an easy way to fix it, with readily available components (with the usual craftsmanship)


First remove the old regulator :


It's the small 5 pin chip marked U1 here. It has been removed with just a blob of solder

(no hot air, too much plastic nearby).

Now let's do a ugly hack on the other side using a SMD ASM117 3.3v chip:


As a bonus, the ASM117 will take much more abuse and will provide much more current

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