SOLVED Lectrc-FX OLD Chap - Filter Matrix Mode knobs don’t change sweep

[mkstewartesq]

Need some help with the Lectric-FX Old Chap, please. This is a clone of the EHX Electric Mistress, which had a “filter matrix“ mode whereby you could stop the flange sweep and then manually adjust the sweep using the Range knob. I’m having a very specific problem with the filter matrix mode in my build.

Generally speaking, the non-“filter matrix” mode works just fine – great flanging, all knobs working as they should, etc. When I flip the filter matrix switch DPDT toggle on (up), the sweep freezes as it should, but none of the knobs work to manually change the sweep. The sweep just stays frozen at whatever point it was when I flipped the filter matrix switch on.

Things I have tried:

• I tested for continuity on all of the relevant lugs on the DPDT (on-on) for each of the two positions. Everything seems fine there and, as noted, flipping the switch causes the sweep to freeze as it should (and turning it back off causes the sweep to begin, well, “sweeping” as it should. So I assume the DPDT is fine but wanted to double check it anyhow.
• I tried audio probing and could not find a problem, although, to be candid, the schematic is far too complex for my current level of knowledge so I am relatively certain that I’m not following the proper path.

So, in short, the DPDT seems to be working as it should when “filter matrix mode“ is turned on but something is happening after that such that the Range knob has no effect on manually altering the sweep.

Pictures attached (sorry the board is still so fluxy) and a schematic. Please note that R 23 and C 17 are empty because I am building “revision C” of the pedal and the build documents instruct to omit those two components when building that revision.

Any thoughts or assistance appreciated.

Mike

 

[mkstewartesq]

Going to mark this as solved. For building the version that I am building, the documents state merely to “Omit R23 and C17”. After consultation with Lectric-FX it turns out they also want you to jumper R23 (but not C17) although the build documents don’t make that clear. Once I put in a jumper, everything works.

Mike