Hi
I plugged in my Veils module backwards. Burnt smell 
I’m hoping it was polarity protected.
Any ideas?
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pics of both sides of the board would help.
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Weird. +12V rail has a diode on it and -12V rail has a resettable fuse on it.
So one side’s protected against reversal and the other side’s protected against shorts?
Oh wait, VEE also has a diode to ground. Could be that’s what you smoked and if the fuse tripped soon enough it might have protected the rest?
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I hope so, AO.
I feel pretty dumb. I was so sure I had checked the cable properly.
I’ll give the fuse a good chance to reset, and then test the voltages on each side of the diodes.
Sound’s like a daylight job for tomorrow - I’m an old fart (eyesight does get poorer) and I hate soldering and probing in artificial light unless I have too.
Let us know what you find, it’s a good test of two different protection schemes.
The schematic linked above has the Eurorack power connector backwards. Pin 1 should be -12V
So if you use a polarized connector to prevent further mistakes, make sure it is installed backwards on the PCB too.
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It would appear that L1 (to the right of P1) has left the building!
I’ve checked the fuse P1 and I can measure resistance across it. Does this mean it has reset?
I’m hoping that replacing L1 may resurrect the module. Any thoughts or advice?
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That was not the expected result, looks like the protection circuit didn’t do it job quite right.
Yeah, it should probably measure between about 0.5 ohms and 3 ohms, unless it’s been replaced by a 0 ohm resistor (it is marked 0 and it would explain why the ferrite has blown).
There is a good chance that should do teh trick.
You can probably replace it with anything between a short and 1K, I would recommend you first check that D1 has not blown and still acts like a diode, because, if D1 has blown, there could be more extensive damage.
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Thanks very much for the tips.
Unfortunately D1 shows no connectivity on either side with the multimeter. So that will also need replaced.
Looks like half the power connector isn’t soldered, which means twice the current on the half that is. Not relevant to the present problem, probably, but not good.
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I think that may be the case. Bourns uses a single digit part identification on their PTCs, with 0 being one possibility, but Bourns PTCs look different with a semicircular notch on each end. On a quick look at Mouser I don’t see any other PTCs labeled with a single digit.
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Yeah, I noticed this too but it’s never been a problem in the past. The same person in Taiwan does all my smd work and sometimes they also solder on the power header - and their work is great in my exerience.
I think I have to take all blame for this error. Just hoping I can fix it.
Not soldering all the power header pins is poor practice, and if they substituted a 0R resistor for the PTC, then that left the module unprotected against a short it should have been able to handle. Not talking about blame here, though I don’t think it’s all yours; just saying the assembly could have been done better.
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Thanks AI
A fair point to consider.
Marc
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Just rechecked with a multimeter and D1 actually seems to be ok.
When I get the courage up, I’ll have a got at removing the blown ferrite with a jumper.
Thanks again for the help.
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Success!
I dabbed a blob of solder across the destroyed ferrite. That’s as far as I’m prepared to go with smd for the time being.
Phew! It’s back in business 
I promise to be good and always check twice in future.
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glad it worked out for you , that plugged it in backwards feeling really sucks . sometimes it pays to be lucky 
.
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and another post from months ago that I am just seeing for the first time and not looking at the date lol .
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In Preferences >> Interface, do you have Default home page set to Latest?
i think so , latest posts are usually listed at the bottom of page . but it doesn’t seem like I see all of them sometimes
it wasn’t . I have changed it , thank you .
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