Trying to verify the function of a part marked S8RF on a Pro Mini clone. It's almost certainly a (5V) voltage reg but it appears failed and I'd like to know what its specs are or were.
Also.. what's with the 0 jumper? Is that someone's way of avoiding paying for a fuse? This may explain how the reg got fried..
Thanks!
Very common to select options, bridge a trace, etc.
S8RF is not in this database. Please post a better picture showing ALL the pins and more of the surrounding parts.
Please provide the details about that.
Heres the whole board. Its the only one I have, so can't take any shots of the back.
And I'm generally aware of why zerohm jumpers are used. Its this specific case I ask about as I dont recognize a fuse..
Waiting...
That probably is a voltage regulator, but you've given us no reason to believe that it failed.
What mistake did you make?
Its this specific case I ask about as I dont recognize a fuse.
Maybe there is no fuse.
9V on Vin pin results in 1.4V on the 5V rail.
** with only 1-2mA being drawn..
Feeding 5V to the 5V input / rail powers up the board just fine.
My mistake? Perhaps just using this particular clone. 
Google search an looking at images, then when to matching Chinese site. Google translate gives this:
" ME6211C50M5G-N SOT23-5 SMD LDO voltage regulator S8RD S8RF new original authentic".
Do you have any Pro Mini schematic handy? You might get a replacement part number from that.
There are probably hundreds or thousands of LDO's that would work there. The pinouts are usually the same, too.
It's futile to try to find the exact same part.
Stand alone, or plugged into the white motherboard you showed? How do you know that some other part is not just drawing excess current and dragging the regulator down?
Please, please don't reply by going back and editing posts. It makes the thread nearly impossible to follow...
Sorry, I'm new to this forum & software and the replies are coming in faster than expected. Also not sure how to quote + reply to posts.
Anyway, it draws almost no current from Vin, it's not overloaded. I'm a retired pro tech (20 years in vacuum tube audio) so I have some idea whats what.. just pointing out that I'm not an electronic newb.
Okay what is the situation here? Pro Mini is about $2.50 in hardware. Why not just toss it?
Sorry, but again, that is not conclusive. You already suspect the regulator is borked. Because of that, it proves nothing about the circuit downstream from it.
The Mini is soldered to the main PCB. No unplugging.
Ill probably just end up replacing the Mini, as I have no SMT rework tools or the skill to use them.
Here it is:
IIt's a MOS KIM-1 clone, "KIM Uno".. a kit.
Did you catch the post where I said that if I power it via the 5V pin it operates perfectly? Im 99% the reg is bad.. as to how that happened, I have no idea.
I wasn't present/ didn't do it.
Powered up...
I thought you told us you tried it stand alone. I see now you didn't answer the question. So now how do you know the problem isn't on the white board?
Did you catch my reply to that?
If you are trying to power that display from the regulator output, that could be the problem. Please post a complete schematic diagram of the interconnections in setup.
Why not simply replace the regulator? It's not unobtainium.
But, I can tell you from decades of fixing stuff like this, the faulty part isn't always the one that is the obvious one.
Do you have any other Pro Micro around?
