Phatty: what's inside?

The Moog Forum Little Phatty & Slim Phatty Forum
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Speculation on what the next incarnation of the Phatty will be… will it be rack mount, a desktop, something else? Curiosity got the best of me and I opened the hood to see how many boards and of what size we are dealing with.

Here’s part 1 of my report [part 2 will be posted as a response]

For starters, mine is a Tribute with the 2.0 code upgrade (increased memory, etc) and the CV output mod. Your Stage edition might be different.

The Voyager Old School (VOS) shares the “Analog” board with the Voyager. This is the board that Bob Moog famously placed under his armpit in “Moog Movie”… he also knocks on it with great joy and pride just before diving into the general architecture of the board. It’s famous.

The Phatty doesn’t have this, it has but a single board containing all controls, analog circuitry, display, etc. The only thing which is separate is the Power supply shown in fig 2. the jack plate shown in fig 3. and in my case, the CV mod board which is very small and is wired from a) board points, b) connectors, and ultimately to the 1/4" jacks on the right side of the Phatty. [again, your Stage I or II might be wildly different, but why mess with perfection!]

WARNING - DO NOT ATTEMPT THIS; I have a background in Electrical Engineering and was willing to risk my warranty for science! If you are dumb enough to sneak a peek at your own Phatty or any AC equipment, be sure to remove all cables, especially Power!

fig 1. opening the hood
Four screws and you’re open. Despite there being 3 screws on left and right sides (on sheet metal), only the upper and lower points are attached. Pay attention since the upper screw [left in the pic] is a sheet metal screw; the lower is a machine screw. Once all four screws are out, the panel tilts up, however note that it is not hinged.

Everything is on a single board but there are series of wires and connectors snaking from power supply and connections back to the board.

fig 2. power supply - where it all begins (the joy of watching your Phatty power up is like no other; it’s a light show that Voyager owners just cannot understand)

On the right side of this pic at the bottom of the Phatty is the power supply. Note the two wires (Black and White) which come off of the AC connector; the Ground is wired directly to the chassis and elsewhere. The connector on the left brings various voltages to the main board (2G, 2Y, 1R).
fig 3. jack plate - the left side of the Phatty (shown atop this picture) note two ribbons for carrying Control Voltage , audio, and Midi (Stage has a USB connector also).
(continued on Part 2)

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Continuing on to part 2…

Repeated WARNING - DO NOT ATTEMPT THIS; I have a background in Electrical Engineering and was willing to risk my warranty for science! If you are dumb enough to sneak a peek at your own Phatty or any AC equipment, be sure to remove all cables, especially Power!

pic 4. CV mod - The CV mod brings Gate Out, Pitch CV Out, Mod Buss out, Volume env out, and Filter env out to the right side of the Phatty (as seen here on the left side of the screen). A factory upgrade/install-only option, it adds a daughter board (seen on left side of screen at bottom) which bridges the 1/4" jacks from various board points (red, orange, yellow, brown, black wires shown on the right side of the board) and from two points behind the Envelop Generator section (red, green wires) which connect via pin connector at top edge of the daughter board. (on the right side of this pic, you can see the power supply).
pic 5. CV attach points - seen here, slightly out of focus (sorry 'bout that) you can see yellow, orange, red wires which are connected to the CV daughter board in the pic above. Note that Moog does this by hand in the Tech Support department and it is VERY tedious work (precise soldering). IF you have an LP with with CV mod and are actually planning on opening yours, be very very careful as these will be the first to break loose if you drop the panel or pull to aggressively!
pic 6. Mid-board view - There’s Bob’s signature on the back of my Tribute. He must have used a really Phat sharpie (!!). In this shot, you can see all of the attach points and the overall real estate that we are dealing with. If you look closely, 3 of the 4 potentiometer attach points are visible from behind; the easiest one to spot is just above and between the red and yellow attach points.

Two other things to point out, the ivory colored connector on the right side of the picture which is likely used by Moog techs during calibration and diagnostics during build. And directly to its left is an unused series of contacts on the board with text suggesting I/O expansion… possibly an upgrade that was never implemented.
That’s all for now (at my 3 picture limit again). Hope you enjoyed this glimpse.

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Thanks for showing us the insides.

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Yes thanks. I have wondered what that looks like. I also wish that someone would show us the inside of those Taurus. Im not going to think about opening mine up. I saw the frame they rigged up at the factory to house the panel for service, im not going there lol.

I also remember watching Bob whack that board and I was cringing but then again if anyone knew about it, it was surely him lol. More flashbacks of my father saying “Delicate expensive delicate” whisped through my mind when he did that lol.

Hope you don’t need any warranty work done or else this post is going to bite you heh.

Thanks again.
Eric

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I won’t be opening my Taurus up either!! It’s happy beneath my keyboard stand and that’s where it’s staying. I almost gave myself a double hernia putting it there in the first place so I’ll leave the task to somebody else.

I’ve been in my Voyager Old School to insert the VX-351 adapter (or at least I thought that’s what I was going to do until I realized it wasn’t required!).

[New School] Voyager is much more tight due to the CPU, display, touch pad, etc.

Am about to crack open the VOS again to solder in a trim pot in place of a fixed resister so that I can better tune for use with other CV equipment. Sounds like a hack but Moog actually provided me with instructions and the part.