Electronics > Projects, Designs, and Technical Stuff
I have a short ( i think) and don't know where to start
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sokoloff:
IOW, Take a simplify, divide, and conquer approach. That tends to let less smoke out of things, though frustratingly still not zero...  :palm:
mikerj:
Are you just replacing the one blown up diode each time?  It's quite possible that one or more of the other diodes has gone short circuit internally.
nick_d:
I think you need all diodes, however if you are just trying to validate the low voltage, low current operation you can put small signal diodes, like 1N4148 instead. I realize it is a hassle assembling the board up like this (try not to get solder in the through-holes) but much cheaper and less frustrating when things are not working right.

As to where to put the DC voltage, when I said put a DC voltage U1/U2 I meant ACROSS U1 AND U2, I realize that can be confusing as it could have meant EITHER U1 OR U2. Anyway put it across U1 and U2 in a polarity that simulates the positive half of the cycle then reverse the polarity to simulate negative half, discharging the cap in between to check you can recharge it with either polarity input (or better, use a dummy load such as a lamp, but be careful not to introduce new problems or shorts via the load, and don't use the real load as it may be the cause of the original issue).

cheers, Nick
fsr:

--- Quote from: Hextejas on December 16, 2018, 04:08:13 pm ---
--- Quote from: PA0PBZ on December 16, 2018, 03:48:43 pm ---Ehm… if what I see is correct then I found your problem… Are the 4 pads with the red line all connected to each other?



--- End quote ---

No, they are not. But thanks for looking.

--- End quote ---
It looks like there isn't a lot of clearance between the big track and the pads inside of it. Make sure that only the pads that must be connected to the big track are actually connected. Solder can cause short-circuits with such a small clearance (the solder mask should avoid it, but it doesn't harm to check). Even the terminals themselves could make a short to the track, if the wide section of the terminals bite into the solder mask.
Two pads from two of the diodes of the bridge should be connected to the big track which should go to one terminal of the capacitors, while the other two diodes are connected to the other terminal of the capacitors. The catodes of the diodes go to the positive terminal of the capacitors, while the anodes go to the negative terminal.
Possible source of confusion: C10 must be connected only between U9/U5 and U8/U12. When wires are crossed, they must be connected only if there is a red circle over the crossing. If there's NO red circle, the wires just pass over each other, and they should NOT be connected.

With no load connected, there should be no interaction between the top and bottom diode bridges, besides C10, which won't do anything until the grounds are connected together.
james_s:
For testing, wire a 60-100W incandescent lightbulb in series with the power input, that will stop you from losing all the magic smoke each time something goes wrong, and you'll have some time to take measurements under power and see what's happening.
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