DIY Drummer
Member
- Joined
- Apr 11, 2021
- Messages
- 6
Foolishly thought I could tackle the AML 1084. I was warned. I was almost successful.
Everything works perfectly (as far as I can tell) except for the High Frequency shelf. All of the other EQs work, and they seem to boost and cut as they should based upon the signal readout and the EQ profiles (at least in LINE mode where I was able to directly measure roughly using a signal generator insert and ProQ3 on the back end). I don’t get any noticeable boost or cut in the volume when the EQ section is bypassed and then switched in. The only odd noise I hear when doing anything with the HF Shelf is a pop when switching to 10, 12 and 16, and it tracks too. You will hear the pops in a recording, and see it in the waveform. This doesn’t happen with the other EQ bands or Filters – they are dead quiet when switching. Otherwise, the unit seems dead quiet in both mic and line mode. The unit sounds and behaves almost as if the HF shelf just doesn't exist except for those switch pops. I'm starting to think there is something fishy in the switch or close to the switch.
I’ve checked my solder bridges/joints, board continuity, and component codes as best as I can (I’m colorblind, so the resistor codes can be tricky). I’ve tried to trace everything as best as I can without desoldering all the boards.
Any suggestions, possibly on a specific section of the circuit to re-re-examine? I'm getting a strong trace through R116 into the HF, and also out of R100. I was getting a comparatively weaker trace coming back out at PL9. I was digging around in Opamp A and may be getting an unwanted dropout across R123, but I may be misreading the diagram there.
Thanks!
Everything works perfectly (as far as I can tell) except for the High Frequency shelf. All of the other EQs work, and they seem to boost and cut as they should based upon the signal readout and the EQ profiles (at least in LINE mode where I was able to directly measure roughly using a signal generator insert and ProQ3 on the back end). I don’t get any noticeable boost or cut in the volume when the EQ section is bypassed and then switched in. The only odd noise I hear when doing anything with the HF Shelf is a pop when switching to 10, 12 and 16, and it tracks too. You will hear the pops in a recording, and see it in the waveform. This doesn’t happen with the other EQ bands or Filters – they are dead quiet when switching. Otherwise, the unit seems dead quiet in both mic and line mode. The unit sounds and behaves almost as if the HF shelf just doesn't exist except for those switch pops. I'm starting to think there is something fishy in the switch or close to the switch.
I’ve checked my solder bridges/joints, board continuity, and component codes as best as I can (I’m colorblind, so the resistor codes can be tricky). I’ve tried to trace everything as best as I can without desoldering all the boards.
Any suggestions, possibly on a specific section of the circuit to re-re-examine? I'm getting a strong trace through R116 into the HF, and also out of R100. I was getting a comparatively weaker trace coming back out at PL9. I was digging around in Opamp A and may be getting an unwanted dropout across R123, but I may be misreading the diagram there.
Thanks!
