I’ve just finished building @BenRufenacht’s clock module. However, when I power it on, nothing happens at all - no screen, no activity on the nano, nothing at all. It appears to me that nothing is happening on the 5v rail. I tested voltage between the ground and output pins on the 7805 and i see less than one volt. I see ~12v on the input pin as expected.
I would assume this meant a bad part, but I’ve seen this same behavior on 3 different regulators. Is it possible that something else in circuit could be causing this bad reading on the regulator? or did I just end up with a bad batch of these?
I tested the two that I’ve pulled out already. One tested fine, however the other had a full 12v on its output. I do not know the order in which these two were tested. Now I’m wondering if that bad regulator fried the nano
EDIT: Maybe not. I just tested between the 5v and GND pin on the nano’s socket and even there I’m seeing less than 0.01x volts - so it’s just not getting power. There’s nothing at all between it and the regulator. I also put in a new nano just in case - with no effect.
From the schematic on Github, it appears the +5 V regulator output connects to Arduino VIN, not +5V. That’s not best practice; the VIN pin is meant to connect a +7 to +12 V supply to be regulated on board the Nano down to +5 V. +5 V at that pin is too low; the Nano will probably function but it should have more voltage. If using an external +5 V regulator it should be connected to the +5V pin. But the good news is, if you connected +12 V to the VIN pin, the Nano should be just fine.
Neither pin is going to love ~.006v either though.
Should I be able to test the 5v output pin in-situ. I will be testing again but it did seem as if I got different readings with the regulator installed than after it was pulled.
After stepping away for a couple days, I just performed another test and I’m completely baffled.
The module still would not power up at all so I tested across the ground and output pins of the regulator and I see <1v again while it is soldered into the board. Also of note: the regulator is getting quite hot even with a heatsink attached.
I pulled the regulator out and put the very same one into my breadboard test setup as @analogoutput recommended. In this configuration I see a beautiful 4.999v.
The only thing between the power input and the 5v rail is a ferrite bead and this regulator. I’m at a loss as to how it could be behaving differently on the board than it does in the breadboard.
Yep, there does seem to be a short in the UI board somewhere. I don’t see anything obvious in any of my solder joints. I wonder if the display itself has a short in it. (EDIT: Nope, not the display)
I believe my solder jumpers are correct. My OLED pins are ordered “GND, VCC, SCL, SDA” and I’ve jumped JP2 and JP3.
I think I might have just derped my way into finding the problem.
When you zoom in, the board appears to be designed with JP1 and JP4 bridged w/copper but there’s solder mask OVER the bridge so you can’t actually see it with the naked eye. My OLED needs the other two Jumpers bridged. I’m going to just play it safe and order an OLED with reversed GND/VCC pins.
