Wondering if someone can give me a hint. I'm thinking I have a problem with the Mod 2 ext input on my Voyager, I've a message in to tech support, but I figure I would post here and see if someone might be able to point me in the right direction. I've followed the circuit though the Mod 2 input to the bus multiplex section. From the jack to the analog pcb at cn2 pin 7 I see the correct triangle lfo wave from my MP-201 on my scope (+/- 2.5V centered at 0V) . At the bus source select multiplex ICs U1 and U9 pin 1 on both and at the accessory port cn3 pin 6 I see a negatively biased and chopped version of the original input wave. The thing is this, the analog pcb is multi-layered, I cannot trace from cn2 pin 7 forward or back from ICs U1 and U9 or cn3. All of those points show no traces on the top or bottom of the pcb. I'm assuming there are components in between which may reveal the problem, but I have not had any luck in finding that point. Obviously I don't have the schematics and the above is from retracing the circuit by eye and guess, but if someone could give me a hint as to an component id or pcb section I would be grateful.
Thanks
Mod 2 Input Problem
Re: Mod 2 Input Problem (part 2)
Ok,
Not there yet, but further along. The Mod 2 bus input signal also goes to the left, then right panel pcbs, then to the digi PCB, from there to the analog pcb. I don't know for certain about the other source choices as to whether they go through the digi pcb, but the all look fine at their respective pins on U1 on the analog pcb. When the Mod 2 signal is coming off the digi pcb it is composed of a collection of various pulse waves, this is why it is looking chopped (staircase steps). I can see the original signal up to U16 on the digi pcb, the output from U16 is hardcore digital (looks the same as the other DG408s nearby U22 & U28 0-+5v digital signal, 0- neg.5v the triangle wave from the Mod2 jack, the triangle wave disappears when i remove the connection to Mod 2. Whats interesting is that I see the correct wave at pin 12 U16, I do not see it at any of the pins on U22 & 28, but I do see the negative triangle wave at their outouts ). This is as far as I have it.
Not there yet, but further along. The Mod 2 bus input signal also goes to the left, then right panel pcbs, then to the digi PCB, from there to the analog pcb. I don't know for certain about the other source choices as to whether they go through the digi pcb, but the all look fine at their respective pins on U1 on the analog pcb. When the Mod 2 signal is coming off the digi pcb it is composed of a collection of various pulse waves, this is why it is looking chopped (staircase steps). I can see the original signal up to U16 on the digi pcb, the output from U16 is hardcore digital (looks the same as the other DG408s nearby U22 & U28 0-+5v digital signal, 0- neg.5v the triangle wave from the Mod2 jack, the triangle wave disappears when i remove the connection to Mod 2. Whats interesting is that I see the correct wave at pin 12 U16, I do not see it at any of the pins on U22 & 28, but I do see the negative triangle wave at their outouts ). This is as far as I have it.
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thealien666
- Posts: 2791
- Joined: Mon Nov 14, 2011 8:42 pm
- Location: Quebec, Canada
Re: Mod 2 Input Problem
Uh, I think your talking to yourself there yesman... I'm an electronic hobbyist with 30 years experience behind me, and I haven't been able to follow you... 
You didn't mention what was the initial problem with Mod 2, or what were the symptoms or abnormal behavior...
Reverse engineering more than one double-sided PCB is quite a task, especially without schematics. I'm not even sure that the main analog board #11-404P is only a 2 layer board ? It might be more than 2. In which case following traces would be near impossible.
I think you'd better write Moog Music service department and ask for the service manual, along with schematics...
Or better yet, let them sort it out maybe ?
Anyway, good luck.
You didn't mention what was the initial problem with Mod 2, or what were the symptoms or abnormal behavior...
Reverse engineering more than one double-sided PCB is quite a task, especially without schematics. I'm not even sure that the main analog board #11-404P is only a 2 layer board ? It might be more than 2. In which case following traces would be near impossible.
I think you'd better write Moog Music service department and ask for the service manual, along with schematics...
Or better yet, let them sort it out maybe ?
Anyway, good luck.
Moog Minimoog D (1975)
DSI OB6
DSI Prophet REV2
Oberheim Matrix-6
Ensoniq SQ-80
Korg DW8000
Behringer DeepMind 12
Alesis Ion
DSI OB6
DSI Prophet REV2
Oberheim Matrix-6
Ensoniq SQ-80
Korg DW8000
Behringer DeepMind 12
Alesis Ion
Re: Mod 2 Input Problem
Yeah, I know. Same experience here with 15 in elec. production, a number of years buying faulty Prophet 5s, etc. and restoring them. I was trying not to wander too far into it all and hoping there was someone familiar with this section on the forum. I have a message in to Moog in hopes for the schematics. The problem is that if I input a square wave centered around 0V (+/-2.5V) and raise the amount pot, I will get two pitches moving away from each other which is good but also both pitches will drop as if there is a negative bias. Had a look at all my inputs there is no negative dc. The wave is good until it gets to the digi pcb. Yeah, I know there is at least a ground plane layer on the analog pcb, so even with a flashlight you cannot follow traces.
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thealien666
- Posts: 2791
- Joined: Mon Nov 14, 2011 8:42 pm
- Location: Quebec, Canada
Re: Mod 2 Input Problem
Aahhh, that's more like it. Now I know what you're talking about.
There might be some DC bias on the external input to the mod busses circuits inside the Voyager (by design), and that behavior might be perfectly normal...?
Have you asked other Voyager owners to check for this behavior on theirs ? (I sold mine a while back so I can't check for myself, sorry).
There might be some DC bias on the external input to the mod busses circuits inside the Voyager (by design), and that behavior might be perfectly normal...?
Have you asked other Voyager owners to check for this behavior on theirs ? (I sold mine a while back so I can't check for myself, sorry).
Moog Minimoog D (1975)
DSI OB6
DSI Prophet REV2
Oberheim Matrix-6
Ensoniq SQ-80
Korg DW8000
Behringer DeepMind 12
Alesis Ion
DSI OB6
DSI Prophet REV2
Oberheim Matrix-6
Ensoniq SQ-80
Korg DW8000
Behringer DeepMind 12
Alesis Ion
Re: Mod 2 Input Problem
Well,
I checked it out again tonight - listening to the audio out, it sounded correct! So, I put it all back together and all seems well. I did remove and reconnect some of the ribbon cables so, who knows, just glad to be hearing what I expected.
I checked it out again tonight - listening to the audio out, it sounded correct! So, I put it all back together and all seems well. I did remove and reconnect some of the ribbon cables so, who knows, just glad to be hearing what I expected.
Re: Mod 2 Input Problem
Well,
Turns out I did blow a chip on my Voyager in my attempt to make right. I found I have no ground in the room I was using, certainly my bad. So red faced, tail between my legs etc.... I've sent the Voyager to Moog to be properly cared for. Just thought I'd post to keep it straight and yeah I know I'm talking to myself again!
Turns out I did blow a chip on my Voyager in my attempt to make right. I found I have no ground in the room I was using, certainly my bad. So red faced, tail between my legs etc.... I've sent the Voyager to Moog to be properly cared for. Just thought I'd post to keep it straight and yeah I know I'm talking to myself again!
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thealien666
- Posts: 2791
- Joined: Mon Nov 14, 2011 8:42 pm
- Location: Quebec, Canada
Re: Mod 2 Input Problem
Nah, you're not talking to yourself...at least I am reading your posts ! (and probably others too, but in "spy mode") 
Best of luck with your Voyager. Wise decision to send it to Moog Music.
Best of luck with your Voyager. Wise decision to send it to Moog Music.
Moog Minimoog D (1975)
DSI OB6
DSI Prophet REV2
Oberheim Matrix-6
Ensoniq SQ-80
Korg DW8000
Behringer DeepMind 12
Alesis Ion
DSI OB6
DSI Prophet REV2
Oberheim Matrix-6
Ensoniq SQ-80
Korg DW8000
Behringer DeepMind 12
Alesis Ion
Re: Mod 2 Input Problem
OK,
Continuing the story, I sent my Voyager to Moog, took a month+, they fixed what I broke and said the Mod 2 bus was fine. Got it back and found that the Mod 2 bus problem was still there. The following is what I sent to Moog.
Well, I have my Voyager back. Thanks for helping fix what I damaged. I am still seeing that original problem that started all of this.
I took some time and did some testing (didn't open the V). I have a VX-351,CP-251 & MP-201. So, I set-up what I am hoping is a situation which you can recreate and see if this is standard operation of the Mod 2 Ext. Input. The configuration is as follows.
CP-251 Mixer OUT to Mod 2 Ext. IN. (no inputs on the mixer used, only the offset pot, master out at 10).
A volt meter, with which I am reading the CV at the Mod 2 IN, the Mod 2 Pedal OUT on the VX and the Pedal Bus OUT on the VX.
The Voyager was set-up with the initialization program. I set the initial V while reading the CP Mixer OUT for each of the examples below, then read the V at the Mod 2 and Pedal OUT jacks on the VX.
Pedal/On Bus Configuration
Source On/Mod 2
Destination Osc 2
Shaping On/ Pgm (Shaping Pgm 1 & 2 set for offset,zero offset values)
Amount 10
Test Results
-5v from CP-251 Mixer (no inputs, DC v set with offset pot)
-5v at Mod 2 jack (VX-351 Pedals outputs)
-4.2 at Pedal jack(VX Bus outputs)
-2.5v CP
-5v at Mod 2
-4.9v at Pedal
0v CP
-4.9v at Mod 2
-4.2v at Pedal
+2.5v CP
+0.07v at Mod 2
+0.136v at Pedal
+5v CP
+5V at Mod 2
+4v at Pedal
The above data is the same using either the Pedal/On or Wheel bus and reading at the corresponding jacks. So, the result of this is if I use pressure as the shaping input the pitch will bend flat and if I use pressure as the shaping input and as an input to the CP mixer from the VX (no DC Offset), the pitch of Osc 2 will bend flat as I add pressure until the CV passing thru the bus hits +2.5V, then it will bend sharp. While this may have its use, I don't believe it is what is intended. Previously when I had thought that the problem had gone away, it was because I was inputting an LFO signal from my MP which had a programmed +2.5V DC offset. I am hoping you can shed some light on this.
Thanks for your time,
Brian
The Tech at Moog was able to duplicate this problem on his Voyager/Vx set-up. Called it a "quirk" and said he would pass this to Engineering. What I am wondering is can someone with an OS Voyager & VX test this. (you can take the V LFO out, look at it on your scope, (centered at 0v +/-2.5v) then plug that into the Mod 2 bus and look at the bus output on the VX. It will be centered at the negative rail (-5v) which is not what the input is - and therefore the lower half of the wave will be lost and it appears to have acquired a bit of gain.) I had traced good signal to the digital board and think that is where the problem is.(I asked for the schematics, but no luck.) I would like to know if this is occurring on an OS V. Also anyone with a Voyager/VX please feel free to test this. If you do not find the same problem, that is if the Mod 2 input works correctly, please post and include your S/N and software rev. I've spent time & money on this and am surprised not to have heard of this before if all Vs are like this. But, I realize many do not use the additional jack I/O.
Thanks for any efforts on this.
Continuing the story, I sent my Voyager to Moog, took a month+, they fixed what I broke and said the Mod 2 bus was fine. Got it back and found that the Mod 2 bus problem was still there. The following is what I sent to Moog.
Well, I have my Voyager back. Thanks for helping fix what I damaged. I am still seeing that original problem that started all of this.
I took some time and did some testing (didn't open the V). I have a VX-351,CP-251 & MP-201. So, I set-up what I am hoping is a situation which you can recreate and see if this is standard operation of the Mod 2 Ext. Input. The configuration is as follows.
CP-251 Mixer OUT to Mod 2 Ext. IN. (no inputs on the mixer used, only the offset pot, master out at 10).
A volt meter, with which I am reading the CV at the Mod 2 IN, the Mod 2 Pedal OUT on the VX and the Pedal Bus OUT on the VX.
The Voyager was set-up with the initialization program. I set the initial V while reading the CP Mixer OUT for each of the examples below, then read the V at the Mod 2 and Pedal OUT jacks on the VX.
Pedal/On Bus Configuration
Source On/Mod 2
Destination Osc 2
Shaping On/ Pgm (Shaping Pgm 1 & 2 set for offset,zero offset values)
Amount 10
Test Results
-5v from CP-251 Mixer (no inputs, DC v set with offset pot)
-5v at Mod 2 jack (VX-351 Pedals outputs)
-4.2 at Pedal jack(VX Bus outputs)
-2.5v CP
-5v at Mod 2
-4.9v at Pedal
0v CP
-4.9v at Mod 2
-4.2v at Pedal
+2.5v CP
+0.07v at Mod 2
+0.136v at Pedal
+5v CP
+5V at Mod 2
+4v at Pedal
The above data is the same using either the Pedal/On or Wheel bus and reading at the corresponding jacks. So, the result of this is if I use pressure as the shaping input the pitch will bend flat and if I use pressure as the shaping input and as an input to the CP mixer from the VX (no DC Offset), the pitch of Osc 2 will bend flat as I add pressure until the CV passing thru the bus hits +2.5V, then it will bend sharp. While this may have its use, I don't believe it is what is intended. Previously when I had thought that the problem had gone away, it was because I was inputting an LFO signal from my MP which had a programmed +2.5V DC offset. I am hoping you can shed some light on this.
Thanks for your time,
Brian
The Tech at Moog was able to duplicate this problem on his Voyager/Vx set-up. Called it a "quirk" and said he would pass this to Engineering. What I am wondering is can someone with an OS Voyager & VX test this. (you can take the V LFO out, look at it on your scope, (centered at 0v +/-2.5v) then plug that into the Mod 2 bus and look at the bus output on the VX. It will be centered at the negative rail (-5v) which is not what the input is - and therefore the lower half of the wave will be lost and it appears to have acquired a bit of gain.) I had traced good signal to the digital board and think that is where the problem is.(I asked for the schematics, but no luck.) I would like to know if this is occurring on an OS V. Also anyone with a Voyager/VX please feel free to test this. If you do not find the same problem, that is if the Mod 2 input works correctly, please post and include your S/N and software rev. I've spent time & money on this and am surprised not to have heard of this before if all Vs are like this. But, I realize many do not use the additional jack I/O.
Thanks for any efforts on this.
Re: Mod 2 Input Problem
Ok, I know its me just posting to me again, but as a matter of reference to someone who might find this useful, I figured I'd put this up. It might spare someone the frustration of trying to sort what their V is doing, being as none of this is documented. It has surprised me that no-one has found this worth looking into, and since the V has been in production for 10+ years I don't see that this will change, so I'll learn to live with it. (And hope for the schematics some day!). This is the chain between me and a Moog Tech, good guy Andy.
Hi Brian,
So I finally had some time this weekend to work on the issue you were talking about, and I think I figured out what is happening.
The voltage range on certain inputs(MOD 1&2 and Volume) at the top of the Voyager is 0 - + 5VDC, and this is initially confusing as to how it actually functions. Normally you would expect CV inputs to accept a (-5)VDC – (+5)VDC range, but since the inputs at the top of the Voyager are actually scanned by the A/D converters on the digital board, and then output to the analog board as -5 - +5, then they actually translate the voltage range to compensate for this. Any negative voltage sent into the mentioned inputs above will be “clipped” at 0V. If using and LFO with negative voltage ranges I suggest sending it through the CV mixer on the CP-251 and adding a positive DC offset to the signal to bring the total range of the LFO above the 0V mark.
That is what you are seeing the 0 – 2.5 range acting as a negative voltage, and then swinging positively when it crosses the 2.5V mark, is because to the A/D conversion the 2.5V mark is the centerpoint.
I hope this was helpful, and I apologize for the long delay in my replay. It has been a busy couple of weeks, and your issue was rather complex. I hope this will solve the problem for you!
Andy,
Thanks for looking into this. I get what you're saying and was assuming that the problem was happening at the digital board also. The manual calls out the Mod 2 input as having a -5V to + 5V range. This was leading me to think I was having a problem. So, If I read what you say correctly an input of 0V to +5V (say an LFO centered at +2.5V) will be read by the digital board and output to the analog board as -5V to +5V, so not only is it shifting the center point of the input signal it is also doubling its amplitude. (I thought I was seeing a gain of 2 at the VX jack.) I'm going to have to check into this later in the week, It sure seems a bit odd, non-standard, incorrect to say the least. I've been working with analog gear Moog modular,ARPs,Prophets... and have built my own modules for 30+ years. I think you have a problem with how the digital board is handling the input signal. If what you say is true then this problem will not happen on a V OS. Which means that the two versions will respond to a CV at the Mod 2 differently. Is this true.
Again Thanks,
Hi Brian,
You are correct it is spreading the range(amplitude) of the voltage on the backside of the digital board where it runs to the analog board. The manual has this printed wrong, and also does not clearly indicate which inputs are scanned and which are not, which is a little frustrating. I have a manual here for the Voyager OS, and it says the same thing about the voltage, so I think this is either a misprint in the OS manual. I unfortunately do not have an Old School in the Service Dept for testing purposes, and we are not making the Old School anymore. But I will test this the next time I have one in for repair and let you know which way that it works for sure.
It does seem a bit non-standard to me as well. I am sure Bob had his reasons when he designed the Voyager, but what those reasons were I do not know. Alas…
One thing of note: The Mod 1 input is designed to be scalar, and always sums to the Pedal buss regardless of whether it is selected as a Modulation Source. Mod 2 is only active when either buss has it’s Source selected as On/Mod 2. The front panel of the Voyager has a misprint n the Mod buss Source section, it says On/Mod 1 when it should say On/Mod 2.
Again, I am sorry this is an inconvenience of the design, and I wish I had figured it out quicker
Andy,
No apologies necessary, you've been a great help in getting to an understanding of this. Thanks for the Mod 1 note and yeah I knew of the panel misprint. I had looked at the V OS manual also and saw the same. Had you a chance to pass this by Engineering? I'd be interested to hear their take on this. I have to tell you I don't like it, the fact that it is also doubling the input amplitude is killing me. To get a gentle vibrato I have to send a small signal in and barely turn up the Bus amount pot. I'd prefer to bypass the digital board for that input and not have to waste additional external modules to get correct functionality, even if I loose programmability on that. I'm just about to wrap-up building a rack of Blacet Research modules and a jack/level translator panel, so I will probably add a bias/level mod to run into first before going to the Mod 2 input. Please keep me in the loop if you find anything further such as the V OS functionality.
Thanks,
Brian
Edit added 04.25
I just had a look at the V XL manual. It refers to the Mod 2 bus input and output bus functions as noted above. 0 to +5V input, -5V to +5V output. So, it appears to be.... Also, noted that the active attenuators have offset pots, which is nice. This is related not because I spend my time delving into the technical aspects (more time with the scope and DVM than with the notes), but I end up here trying to achieve the sound in my head. My desire is to understand the instrument well enough so that as I hear a sound I can get to that with the least amount of head scratching, which takes me away from the musical moment.
Hi Brian,
So I finally had some time this weekend to work on the issue you were talking about, and I think I figured out what is happening.
The voltage range on certain inputs(MOD 1&2 and Volume) at the top of the Voyager is 0 - + 5VDC, and this is initially confusing as to how it actually functions. Normally you would expect CV inputs to accept a (-5)VDC – (+5)VDC range, but since the inputs at the top of the Voyager are actually scanned by the A/D converters on the digital board, and then output to the analog board as -5 - +5, then they actually translate the voltage range to compensate for this. Any negative voltage sent into the mentioned inputs above will be “clipped” at 0V. If using and LFO with negative voltage ranges I suggest sending it through the CV mixer on the CP-251 and adding a positive DC offset to the signal to bring the total range of the LFO above the 0V mark.
That is what you are seeing the 0 – 2.5 range acting as a negative voltage, and then swinging positively when it crosses the 2.5V mark, is because to the A/D conversion the 2.5V mark is the centerpoint.
I hope this was helpful, and I apologize for the long delay in my replay. It has been a busy couple of weeks, and your issue was rather complex. I hope this will solve the problem for you!
Andy,
Thanks for looking into this. I get what you're saying and was assuming that the problem was happening at the digital board also. The manual calls out the Mod 2 input as having a -5V to + 5V range. This was leading me to think I was having a problem. So, If I read what you say correctly an input of 0V to +5V (say an LFO centered at +2.5V) will be read by the digital board and output to the analog board as -5V to +5V, so not only is it shifting the center point of the input signal it is also doubling its amplitude. (I thought I was seeing a gain of 2 at the VX jack.) I'm going to have to check into this later in the week, It sure seems a bit odd, non-standard, incorrect to say the least. I've been working with analog gear Moog modular,ARPs,Prophets... and have built my own modules for 30+ years. I think you have a problem with how the digital board is handling the input signal. If what you say is true then this problem will not happen on a V OS. Which means that the two versions will respond to a CV at the Mod 2 differently. Is this true.
Again Thanks,
Hi Brian,
You are correct it is spreading the range(amplitude) of the voltage on the backside of the digital board where it runs to the analog board. The manual has this printed wrong, and also does not clearly indicate which inputs are scanned and which are not, which is a little frustrating. I have a manual here for the Voyager OS, and it says the same thing about the voltage, so I think this is either a misprint in the OS manual. I unfortunately do not have an Old School in the Service Dept for testing purposes, and we are not making the Old School anymore. But I will test this the next time I have one in for repair and let you know which way that it works for sure.
It does seem a bit non-standard to me as well. I am sure Bob had his reasons when he designed the Voyager, but what those reasons were I do not know. Alas…
One thing of note: The Mod 1 input is designed to be scalar, and always sums to the Pedal buss regardless of whether it is selected as a Modulation Source. Mod 2 is only active when either buss has it’s Source selected as On/Mod 2. The front panel of the Voyager has a misprint n the Mod buss Source section, it says On/Mod 1 when it should say On/Mod 2.
Again, I am sorry this is an inconvenience of the design, and I wish I had figured it out quicker
Andy,
No apologies necessary, you've been a great help in getting to an understanding of this. Thanks for the Mod 1 note and yeah I knew of the panel misprint. I had looked at the V OS manual also and saw the same. Had you a chance to pass this by Engineering? I'd be interested to hear their take on this. I have to tell you I don't like it, the fact that it is also doubling the input amplitude is killing me. To get a gentle vibrato I have to send a small signal in and barely turn up the Bus amount pot. I'd prefer to bypass the digital board for that input and not have to waste additional external modules to get correct functionality, even if I loose programmability on that. I'm just about to wrap-up building a rack of Blacet Research modules and a jack/level translator panel, so I will probably add a bias/level mod to run into first before going to the Mod 2 input. Please keep me in the loop if you find anything further such as the V OS functionality.
Thanks,
Brian
Edit added 04.25
I just had a look at the V XL manual. It refers to the Mod 2 bus input and output bus functions as noted above. 0 to +5V input, -5V to +5V output. So, it appears to be.... Also, noted that the active attenuators have offset pots, which is nice. This is related not because I spend my time delving into the technical aspects (more time with the scope and DVM than with the notes), but I end up here trying to achieve the sound in my head. My desire is to understand the instrument well enough so that as I hear a sound I can get to that with the least amount of head scratching, which takes me away from the musical moment.
Last edited by yesman on Fri Apr 26, 2013 7:07 am, edited 5 times in total.
Re: Mod 2 Input Problem
This is a fascinating read! 
I hope they fix the problem eventually.
I hope they fix the problem eventually.Minitaur, CP-251, EHX #1 Echo, EHX Space Drums/Crash Pads, QSC GX-3, Pyramid stereo power amp, Miracle Pianos, Walking Stick ribbon controller, Synthutron.com, 1983 Hammond organ, dot com modular.