Moog Music Forum

Finally! And, before anything else, thank you to Markyboard and everyone else here in in the groups that helped me figure out things as I went along. This was a big job, no question about it. A lot was changed, and I am sure it's been improved. I did a burn-in overnight after tuning all 6 voices an...

Trying to understand that but I’m not sure I follow- I had replaced every trimmer on all voice cards so naturally I expected there to be huge differences in value after they were installed. I got the first voice card in tune, didn’t take too long. Card 2 is giving me such a headache. I wonder though...

The problem I'm having now is just getting the replacement trim pots to line up in close enough range, and every time I think I have it, I don't. I've been on Voice card 2, oscillator 2 now for 2 nights. The problem is if you turn a trimmer too much, and one not enough, then you run out of turns.......

Tell you something....

I wish I had maybe thought about adjusting my voice card trim pots to half of their resistance before putting them in... I’ve never been so frustrated trying to range and scale an oscillator! Hours!

My scope went bunk on me - did a factory reset on it and it came back normal. I wasn't even seeing a sinewave on that resistor until I reset it. Ended up doing the Vpp measurement since my scope had the option.

Were you ever able to successfully do the filter tuning section of the calibration? https://live.staticflickr.com/65535/50708081203_ea92393cfd_z.jpg First off, I don't have a 400F AC voltmeter, and I'm not going to get one. I had originally tried this calibration before I messed everything up and st...

Buddy...

My P28 cable was BACKWARDS

It seriously took me looking at a closeup of someone else's online to be like... wait a minute.... God, I'm an idiot.

Well, I've made some progress (yay?) I fixed my noise problem (or, lack of noise control). Apparently I bent a fairly important pin on the 4051 in the sample/hold circuit that just happened to be the noise amount. Didn't notice it, again, until I pulled the DMUX board, again :roll: I replaced all th...

Thanks... I hear you, and I realize I’m messing around with a synth that most techs won’t even touch, but I’m not afraid of stuff like this even with limited knowledge. It’s all just parts... and you’re right, I did make a real large change to the system including a new OS that I programmed myself o...

I'm embarrassed to say I don't think I quite understood the sample and hold circuit.... I'm rethinking my DMUX board again. In doing the autotune upgrade, the first instruction was to replace 13 capacitors on the DMUX board. This is where I failed to understand what I was replacing, but replaced per...

Well it's also possible that the sockets I used suck; I had to replace the sockets on the 'bad' voice card since I had gone and replaced them all anyway preemptively. Apparently something there went wrong so maybe I need to re-address the cards individually again, knowing that all it took was one ca...

Okay, things are better, but not totally fixed yet... I do have OSC3 now, and I can calibrate the voice cards with all oscillators in the correct footage/range (by the way someone did at some point reverse the trimpots on these cards so, it may be time to replace; they are a little wonky). So everyt...

Ha.. I removed and re-did my ribbon connector sockets on that voice board with the good gold-plated machined ones and I *think* I'm in good shape now. I'm getting OSC3 now. I stared at that voice card for at least a half hour. Now - I'm not sure I'm out of the water yet; I'm not getting noise (noise...

This really smells of a bad connection on that ribbon cable. Maybe even a short. Not sure if you can reverse the cable as it probably won’t reach all the boards. But maybe try swapping board 1 and 5. See if that reveals anything new. Yup, already ahead of you - I just pulled all the cards again so ...

https://live.staticflickr.com/65535/50654212471_7531008336_z.jpg My luck keeps getting worse and I'm not rushing, so I'm not sure what I keep doing wrong here... I'll start with: "I don't know when that blob of solder dropped on the traces"; it could have been earlier on, it could have be...