WTF my SVF lost its highpass

strange thing: when i played my SVF yesterday just like i did a day before, the high pass filters have both stopped working, which i think is kind of weird. i haven’t changed anything, just powered up again.
the band and low pass of each filter work as they should but the high passes just put out what sounds like the unfiltered signal, very loud. resonance works too, but not the cutoff.
normally i would think there was a bad solder joint that turned into a no-solder joint over time, but both at the same time?
anybody have some idea what could have happened? i forgot to take it home, so i can’t do tests atm.
i was also wondering at first if something on the chip could have been damaged, maybe by some weird power spikes or something (just the first thought) when powering up, but the cvs that control cutoff are the same no matter which filter is selected, and in lp and bp mode everything’s fine.

This is weird. It’s not like the HP is a different circuit than the LP or BP. There is really only one filter core for filter1 / filter2, with voltages at various points yielding the BP/LP/HP modes. If the LP is working, the voltage at the HP point can’t be wrong!

Try the “check the signal at a point on the PCB” technique. There are small markings on the PCB identifying at which points the HP1 / HP2 signals are (IC13 13 ; IC12 13). Try listening to them with and without the 4053 in the socket. But even then it’s weird to have fried two 4053 at the same time.

thanks, Olivier. i’ll check that tomorrow.