Everything You Didn't Want to Know About the Moog Satellite

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Everything You Didn't Want to Know About the Moog Satellite

Postby Don T » Mon Jun 25, 2012 5:47 am

[Moderators: If any of you feel this would fit better in another category, please feel free to move it.]

I've been restoring a couple Moog Satellites, and their rare cousin, a Minitmoog, for about a year and a few months now, whenever I can fit some spare time in (yeah, right :roll: ). As I've been poking around in these things I've come to the conclusion that out of all the different editions of the service manual for these beasts, there is not a single version that is correct. In some cases, following the manual can cause more harm than good. So, I thought it might be helpful to compile as many errors as I can find, make corrections, and post it here to help out anyone else that may be interested (both of you :mrgreen: ).

I'm not going to post it all at once, because my scanner died and I haven't made another thrift store run in awhile. So, this will be a continuing, dramatic and compelling series for the two aforementioned interested parties. The others of you will no doubt pity me for the lack of anything else better to do with my life...

So, here goes, installment 1:

There are two major circuit board revisions, and a few more minor revisions after the first. The very first version is this one:

Image

This early version has the resistor matrix as part of the main board, the square area about one-third in from the right side of the board.

The third version, yes, third, the second version never appears in any service manual I've seen, but I have one, and I'll post photos later as it fits better with another section of this article. Anyhow, the second and all later versions had the resistor matrix moved off the main board:

Image

Ok, so what's the big deal? The parts list in any of the service manuals is only correct for the first version! There is one parts list that all the transistors and ICs are listed by their "house number", or "Thomas Organ Co. part number". The parts list with the Thomas-specific part numbers is technically correct, but if you don't have a way to decipher the part number, it isn't much help.

Again, what's the big deal? If you would like to keep the smoke inside all the semiconductors, this is the big deal: All the parts lists call for the NPN transistors to be 2N3904. This only works for the original board layout. All other versions, the NPNs are 2N3392. You can only use 2N3904 for later versions if you insulate the base lead, and twist the base and collector around so that the collector is in the middle. For most of the circuit board, this would be a royal PITA :verymad: . So if you've tried replacing an NPN transistor and it either didn't work or burned out, now you know why. By the way, I've never seen a first version circuit board. All eight I've worked on, including the Minitmoog, were version two or later.

The good news is, the PNP transistors are indeed 2N3906, except for Q45 (2N4402)

Next Time, depending on having a working scanner or not:

More service manual parts list/schematic errors, OR, how to modify a Satellite board from a Thomas organ to work in a "normal", freestanding Moog Satellite. No, you cannot take the board out of a Thomas organ and just plug it into a Satellite, it won't work (unless you like REALLY strange noises that you will have no control over :P ).
Don Taylor

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(Basically, this means I know just enough about a lot of things to get myself in real trouble)
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Re: Everything You Didn't Want to Know About the Moog Satell

Postby Don T » Thu Jul 19, 2012 8:02 pm

I know it's not usual practice to follow your own post, but editing the first may make things a bit too cumbersome to follow/read. Plus, this is just to test an image, and will be deleted later.

Anyhow, I had decided to scan one of the original schematics and add corrections. This is by no means complete, but I need to see if others find this readable, or too large, or too small, or if the resolution needs adjustment. This version is actually half the size of the image I've been working on, but that one is 20MB! :P

If this works for you, or not, let me know. As I said, there are MANY more corrections to make to this.

EDITED: New photo link added. This is a 3.4MB file.

Satellite Scan
Last edited by Don T on Fri Jul 20, 2012 12:30 am, edited 1 time in total.
Don Taylor

Master of no trades, practitioner of many.
(Basically, this means I know just enough about a lot of things to get myself in real trouble)
Don T
Supporting Member!
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Posts: 303
Joined: Wed Oct 19, 2011 8:28 pm
Location: Marietta, GA
Real name: Don
Gear: Roland SH-09, Korg Polysix, Moog Rogue, Realistic MG-1, Paia Fatman, Korg Monotron, and of course, my main instrument: Trumpet!

Re: Everything You Didn't Want to Know About the Moog Satell

Postby nathanscribe » Thu Jul 19, 2012 10:18 pm

Interesting. Is that BPF followed by a 12dB LP? I do think it needs more resolution as the values and text are difficult to read.
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Re: Everything You Didn't Want to Know About the Moog Satell

Postby Don T » Fri Jul 20, 2012 12:13 am

nathanscribe wrote:Interesting. Is that BPF followed by a 12dB LP? I do think it needs more resolution as the values and text are difficult to read.


Thanks for the response!

Just had a look at the photo coming from the website, looks like tinypic isn't the way to go. What I uploaded was 3.4MB, and 7200 x 3288 pixels. I'll give photobucket a try.

But, to answer your question, that is in fact a 12dB, OTA-based BPF followed by a 12dB Moog ladder lowpass filter. I haven't quite come up with an answer to the question: "Why?" as of yet.
Don Taylor

Master of no trades, practitioner of many.
(Basically, this means I know just enough about a lot of things to get myself in real trouble)
Don T
Supporting Member!
Supporting Member!
 
Posts: 303
Joined: Wed Oct 19, 2011 8:28 pm
Location: Marietta, GA
Real name: Don
Gear: Roland SH-09, Korg Polysix, Moog Rogue, Realistic MG-1, Paia Fatman, Korg Monotron, and of course, my main instrument: Trumpet!

Re: Everything You Didn't Want to Know About the Moog Satell

Postby Don T » Tue Sep 11, 2012 1:30 am

This thread has not been abandoned, it has simply been put on hold temporarily while migrating from old Mac to new Mac. Software/file format issues to deal with.

Helpful hint to any readers: Don't wait more than 7 years between computer upgrades, especially if the entire processor family changes!
Don Taylor

Master of no trades, practitioner of many.
(Basically, this means I know just enough about a lot of things to get myself in real trouble)
Don T
Supporting Member!
Supporting Member!
 
Posts: 303
Joined: Wed Oct 19, 2011 8:28 pm
Location: Marietta, GA
Real name: Don
Gear: Roland SH-09, Korg Polysix, Moog Rogue, Realistic MG-1, Paia Fatman, Korg Monotron, and of course, my main instrument: Trumpet!


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