Not getting +5V anymore

Testing/Troubleshooting
1

Hi, after building a DINx1 module, with great effort, and had it working, i am now facing another problem: my Core doesn’t respond anymore… I have no more the 5V at the 7805 (it gives me something between 0.8V and 1.2V… I didn’t touch the Core while building the DINx1… simply, suddenly, it doesn’t work no more…

Could it be the 7805 broken ?

I’m using a 12V PSU…

What are the steps to debug ? It is frequent to break the 7805 ?

I want to add that yesterday, before things went bad, i had a bad smell of burning…

Very frustrated… My Core worked for a big while, and now that i was going to attach buttons, the enjoyment has terminated :frowning:

Thanks in advance

2

the 7805 will “shut down” if its output is shorted or overloaded.

Unplug all modules from the core, then try again.

If that works, connect each module and power up again, to test each module.

(do NOT connect or disconnect modules while the power is on)

If one of the modules has a short, you’ll find out which one this way.

But if EACH of the modules works fine, but you cannot get ALL of them to work

at once, then you probably have too much load for your 7805. to reduce the heat

on your regulator, you can:

Add a heatsink.

Reduce the DC input voltage to as low as 7.5 volts

Use multiple regulators to power your project.

But probably you’ll find a short and once that’s fixed you’ll be all good.

Have Fun,

LyleHaze

3

Thanks Lyle, but unfortunately the issue i wrote about happens with all of the modules disconnected (i only have a DINx1)..

The strange thing is that i didn’t touch the Core, it simply stopped working…

Anyway, i’ll try searching for a short once again.

Thanks, have a nice time

4

Just looked for shorts… but i can’t visually see them…

I still get only 2V ca at the 7805 output (and 12V on the input obviously)…

The problem is that, apart from visually, i really don’t know how to look for shorts…

For example, i’m trying to use the beep feature of my multimeter… to say one, it beeps touching pin0 and pin1 of J5 (+5V and ground)… is this correct ? does it mean there’s a short ? As i said, no other modules are connected…

Sorry for my ignorance…thx

5

For example, i’m trying to use the beep feature of my multimeter… to say one, it beeps touching pin0 and pin1 of J5 (+5V and ground)… is this correct ? does it mean there’s a short ? As i said, no other modules are connected…

yes, BEEP means short :slight_smile:

S

6

UPDATE:

i changed the PSU to a 9V one… now i have once 5V on the 7805 output… but i still don’t get the MIOS upload requests in MIOSSTUDIO (that i have always got there…)..

I started once the debug process, starting with Vdd measure: in this particular test i have 5V anywhere i should, except from pin TX of the PIC (pin25); in fact, i have here 3.7V..