Very low Ride signal and strange Master vol. noise

Hi everyone! I've finished my build and everythings works but I've got some problems, mainly in the digital section. In particular at the end of the open hihat sound I get a strange double "click", like something is engaging a switch somewhere in the signal path. The issue is already present at the output of the DAC and it's clearly visible on the oscilloscope, so I exclude problems with VCA or Q84. Maybe theres something wrong in the way the closed hat sound gets read from the eprom? I'll try to post a recording of the noise tomorrow. Also I've to mention that the sound from both closed and open hat was perfect when they were just finished, the problem with the closed hat started after I accidentaly reversed the polarity on the power cable. Nothing else seems to have suffered from the incident. Also the ride is REALLY low, even before the incident. Uplugging one of the mux/sh boards brings it to an acceptable level but still lower compared to the Crash. Also the accent pulse that i get when the Ride section is engaged it's huge, way way more than 1 volt. I have to mention I had to swap Q69 with a 2n3904 because one of my 2sc2603 was broken (obviously I bent the leads to be in the correct position). Maybe this is causing the ride output to be so low? Or is it the strange voltage from the accent? Help me please, I'm kinda lost

I had similar issues with the MUX pcbs being the cause. Try u plug both and check if everything sounds good. I wouldn’t look anywhere else at this point as you may be unecessarily damaging components. Mine still isn’t 100% even after building more MUX pcbs.

Thank you druu! I'll try to swap the mux pcbs and see if the problem is still there for the ride. But regarding the Hi Hat I don't think it's related to the mux boards. Here's a sample of the open hi-hat: the two clicks are clearly audible. https://vocaroo.com/i/s02vYIcD1cIl

I've found even with non working mux boards installed if you use the instrument tap the digital section is unaffected by this, and if the circuit is good should sound as normal. ensure you are running the latest fw also. http://www.network-909.de/circuit.htm - good break down of the circuits and here you will find a hi res version of the roland service manual http://www.dinsync.info/2010/02/roland- ... anual.html

Thank you serum! Didn't use your hint to troubleshoot but the problem was indeed one of the two mux/sh boards. I noticed one runned very hot so I swapped it with the other one and the ride was perfect! And no more 1v+ pulse from the accent. Wile I was desoldering the ics from the broken board some copper traces fell of. I can't say if this was a problem inherent to the board itself or if I damaged it with the iron, but obviously the issue was located there. Regarding the hihat I'm almost sure that problem is in the circuits that reads the eprom so I'll try to swap all the ics and see if the problem goes away.

After one moth I'm at this point:

Hihat - after changing every ic in the circuit it turned out to be a damaged eprom. Now it's fine.

Ride - no clue whatsoever. I checked every component, resistor, capacitor, changed opamps, transistor: nothing. The problem is ihnerent to the ride circuit because I tried to swap the crash and ride eprom and the problem didn't move to the crash side. I will go on and change ic53 (74hc174 hex flip flop), c128 and hope for the best.

Master section - I replaced the pot that came with the kit because I damaged it during soldering and it made scratchy noises. Now the volume pot is ok, but when I turn it up I can hear a sound like a low pass filter opening (self-oscillation???). What could it be?