Voyager filter problem - self oscillation

[thealien666]

...Can you please explain me what are the CMOS logic gate in the envelope circuits? So I can focus my tech engeenir who trying to fix it...

I don't have access to the specific schematics for a Moog Voyager, but relying on past implementations of envelopes circuits in Moog synths, there was sometimes a CD4007 (used as threshold detector) used to have the circuit go through the different envelope stages.

One thing that I'm sure of, is that there are some CD4052 (digitally controlled analog switches) chips in there for the different CV routing, and those have failed in another member's Voyager recently (he is still investigating the cause of their failure, and suspect the switching PSU sequencing might have damaged those sensitive CMOS chips by the power rails). But he did not have the problems you show, however.

If you have access to a certified tech (which I am not btw, I'm just an electronic hobbyist) he should contact Moog Music support and ask them if he could get a copy of the service manual for the Voyager. That way, he could have the schematics in front of him and have a better idea where to look for possible failures.

TIFWIW.

[Spav]

Levib

If it is just the Volume envelope causing you problems then get your guy to check the operation of U7. If it is the Filter envelope check the operation of U29.

One word of warning when getting devices off this board is that it is multilayered so be very careful not to damage the plating in the holes as you can destroy the board.

There are no service manuals for the Voyager they are currently in the process of producing them.

[levib]

Hi
So my voyager is in the lab and the problem isn't solved yet
We can't find the source for it but still trying

I wonder if anybody knows where can I get 3.4 OS
I would like to get back to this version.maybe it will fix the problem.
I do not remember this happening before I made an upgrade to 3.5.

[RL]

Here's the link for the 3.4 version (but it will not fix your problem I guess):
http://www.moogmusic.de/Version_3_4.zip

[levib]

Some update about the situation:

the lab couldnt piont the source of the problem and we suggested that it could be one of the switches.
so all these switches been replaced:

U37. U39. U73. U51. U36. U28. U29.U32. U7. U24, U55

unfortunately, the problem still exist. the filter still creates this weird LFO looping.
I even tried returning back to Ver. 3.4, and of course it didnt change a thing.
this is not a natural behavior. I checked a new voyager on store and it acts right.

I'm kinda hopless... don't know what to do.
It's a new synth from store, only two years old since I bought it, and its been in the lab for 3 times already... and still do

[levib]

If it is just the Volume envelope causing you problems then get your guy to check the operation of U7. If it is the Filter envelope check the operation of U29.

One word of warning when getting devices off this board is that it is multilayered so be very careful not to damage the plating in the holes as you can destroy the board.

Hey thanks for your explanation. I saw this only now, but it seems that my lab replaced all these switches already and it wont get better.

thanks for the link for 3.4 - RL

[thealien666]

... all these switches been replaced:

U37. U39. U73. U51. U36. U28. U29.U32. U7. U24, U55

unfortunately, the problem still exist...

Wait a minute. Your tech has de-soldered and re-soldered 176 chip legs, through a 2 layer PCB ??? (11 chips @ 16 pins each)
How much is he getting paid an hour ?

Blindly replacing chips in the hope that it could solve the issue is pretty poor troubleshooting, if you ask me. Those chips are inexpensive, yes, but the time and trouble to replace all of them ? And evidently, and unfortunately, of course it didn't solve the issue.

Is your tech working with the schematics, at least ? If not, his efforts will all be shots in the dark. And you could end-up replacing ALL the chips on that board before hitting upon the defective one, if that's the case at all!

There are over 800 parts on the main analog board alone. Anyone of them could be defective...or not.

Better have a Moog authorized, qualified tech take a look at it. And if he can't find the source of the problem, he could replace the entire board with a new one, and fix the issues for good.

TIFWIW.

[levib]

Not all these chips were replaced in this case but most of them did. There are some of them which has been replaced few months ago on different problems- when the first ossiclator died, and when another problem of a non stoping LFO bias.

The lab has the schematics from moog. But they also told me that its very hard to understand.

This list of replaced chips is ALL the chips on the synth that has been replaced since the first problem.

[thealien666]

I had forgotten that this is not the first problem you've encountered with your Voyager.

This musical instruments from Moog is usually of high quality. It's not normal to have multiple things go wrong with them over such a short time. I would maybe look for something wrong with the switching PSU inside ? Because when things keep failing, one after the other, it usually means that the real source of those problems hasn't been found yet. And one common thing between all of them is the power supply.

[levib]

Thanks thealien666
I'll recommend your idea to my lab
I'll post the news soon

[carlosjaramillo]

God !

I am having a very similar issue with the volume envelope, it starts to open and close when decay is halfway close.

Hope any one could help me here to localize the problem.

Regards.

[Spav]

Carlos, I got your email but if you have exactly the symptoms shown in the video, I would contact levib who started the thread to see if there is a solution to his problem? The info I have is that U7 and U29 relate to the ADSR phases of the envelope and in my case the control lines worked but the switch elements did not. From memory mine looked like a low impedance path on one switch regardless of control logic.

Have a read through this thread again there are some other things to look for suggested by others. With both envelopes set the same try comparing the signals on the working envelope shaper with the non working envelope shaper around U7/U29, I seem to also recall that the control is current not voltage so the signals are not quite what you would expect.

Post a solution if you find one.