F3 Builders Thread

[2 picoDumbs]

I think I have an F3 board somewhere.
I will go look.
It will be easier if I have the board in my hands.

 

[2 picoDumbs]

Both reason are possible.

 

[lordvader]

Here's an unpopulated board if it helps. Had a spare

 

[2 picoDumbs]

I found my F3 boards.
I will just confirm correct orientaion first

 

[lordvader]

Something I might try (if I can find), is replace R19.
It's definitely a 47k resistor - but it might have been damaged (given I'm reading ~300 ohm rather than 47K +).

But my eyes are tired. Going to sleep now.

You've been really helpful

 

[2 picoDumbs]

Diode direction is correct

 

[lordvader]

Dang- don't have any spare 47.5k resistors. Just assumed I had heads lying around :/
In the meantime, I'll reflow everything around the capacitance multiplier curcuit.

 

[2 picoDumbs]

Touch wood.

 

[2 picoDumbs]

If you can't find any shorts, then it's pointing to a leaky bad capacitor.

 

[lordvader]

Well - I put a multimeter across R19, and i read ~400 ohms.
On the functional channel, it read about 38k (i think).

 

[2 picoDumbs]

Bad diode, bad cap, or short.

I don't think it's a bad resistor cause you have current flow where there shouldn't be any regardless of the resistor value.
You could have a short in parallel with the resistor so it's measuring low.

Did you also replace the mosfet Q5?

 

[lordvader]

No - I was going to do that as a last resort - but might be easier than pulling those resistors out.

I'll try that after "work" tonight.

 

[lordvader]

I replaced the diode and the cap yesterday - so highly doubt it's them.
Nothing leapt out as a short on inspection either - but I'll check again.

 

[2 picoDumbs]

Ok replace Q5

 

[2 picoDumbs]

Did you test the diode before you installed it?

 

[2 picoDumbs]

At this point replace Q5

 

[lordvader]

Sounds like a plan - and easier than pulling out resistors and diodes :/

 

[lordvader]

Ah dammit.
I replaced q5, and it was all great! Measuring well, powered up slowly, all good.

Then while checking voltages, I managed to kill q2. I replaced it, and now the pins of q3 are starting to smoke.

Need to leave it alone for a night or two, then regroup.

 

[2 picoDumbs]

Hahahahaha

Good work

I feel your pain.

 

[Rodeodave]

Just a thought, that heatsink compound looks silvery, are you sure it's not conductive?