Hi, I recently built the 1113 ms-20 performance filter, but I designed my own stripboard layout for it. When I power the filter on though, I don’t hear anything (I have the simple 1v/oct oscillator plugged into input 1), and the leds of the filter are not on. I was trying to troubleshoot it but left the power on a bit too long and fried my L7912 on my psu (the heatsink was really hot). I’ve got no clue what is broken or if I did something wrong in the process of converting it to a stripboard layout. I already tried swapping out the 470nF cap, the tl074 and the lm13700 but nothing changed. The schematic and stripboard layout are below.
I haven’t had a proper look, but have you cut the traces under the op amps to stop the legs shorting to the other side? Usually these cut traces would be visible on the layout in some way - usually a transparent op amp, so just checking.
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Yes! These traces are cut, they are on the stripboard layout actually, I just didn’t adjust the alpha values so they would actually show up.
Thanks! I already read a lot of what was said there, I checked the power header and I have no shorts there. The ic’s also don’t get hot when plugging the power in, only my negative voltage regulator on my psu. I also put my multimeter on continuity mode and checked the whole stripboard for accidental solder bridges but could not find any, maybe I missed it but I already checked it twice. Unfortunatly I can’t check the voltages coming from the pins of the ic’s, because I don’t want to fry another power regulator haha
Strange, an L7912 is protected against short circuits. Maybe it’s not a short but is drawing a lot of current, not enough to trip the regulator but enough for it to fry. If so maybe continuity checking won’t uncover it, you’ll need to measure resistance and see if there’s a low resistance from the -12 V rail to ground (or to the +12 V rail?).
I measured the +12V and -12V rail, from +12V to ground there is a resistance of 14,38Kohm and from -12V to ground there is a resistance of 10Kohm.
I am on vacation right now so I won’t have any time to check on possible solutions, but I suppose the resistance I measured is within the expected range?
It’s large enough to not point to an issue that would explain the regulator problem.
Additionally, you have 10Ω resistors in series on your power rails. If there were a short circuit or near short circuit from the negative rail to ground I would expect the result would be to burn out the corresponding resistor, that being its purpose. Since you see no short from the power rail to ground and the resistor hasn’t burned out, consider the possibility that the regulator failure might have been due to either something external to this stripboard, or something before the resistor on the stripboard — so maybe the power header, or maybe the ribbon cable, or the power distribution board, or the PSU itself. In fact I’m thinking a bad ribbon cable might be the best explanation for everything, though I’d still expect the regulator to shut down rather than to fry.
I will test those tomorrow, I don’t expect that those are the issue but its worth giving it a shot. The distribution board is just the output header of my power supply soldered to multiple power headers, nothing else, so maybe that’s a problem?
I tested the cables and those are not the problem. They all worked fine, so the only option left is the distribution board (just some power headers on a piece of stripboard) or the psu itself, the psu I am using is the one designed by moritz klein. There is a small chance that the power header is the problem, but I inspected it and saw nothing wrong with it.
I ended up fixing the problem. I forgot to cut a trace between the +12v and the q1 transistor/the rest of the things there. I looked over that one spot for 4 times… well anyways it is fixed now, thanks for the help!
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